Conversations on Soil Health often focus on row-crop practices like cover crops, no-till, and annual rotations. Orchard and perennial systems play by  a different set of rules. Because these are perennial systems, the root zone remains undisturbed after establishment, which limits opportunities to incorporate soil amendments later. As a result, soil health management in orchards focuses on early decisions and practices that protect the soil over time.

In orchard systems, timing is critical for soil management. Before the first tree goes in the ground is the best opportunity to correct issues such as deep compaction, adjust pH throughout the soil profile, or incorporate organic amendments. Once trees are established, options for incorporating amendments within the root zone become limited without risking root damage. Getting the soil profile right before planting can make the difference between successful orchard establishment and years of managing soil-related limitations. This is a good time to level the low areas and clay-rich portions of the future orchard. Leveling out the planting area can help reduce waterlogging issues and reduce subsequent risk of diseases caused by pathogenic fungi and oomycetes.

Growing Organic Matter from the Top Down

Since incorporation isn’t an option after planting, organic matter has to be built from the soil surface down, through mulches, wood chips, leaf litter, compost, or managed groundcover. These practices moderate soil temperature, reduce evaporation, and support biological activity without disturbing the tree roots. In Florida’s subtropical climate and sandy soils, organic matter decomposes rapidly, making it difficult to build organic matter over time. As a result, surface applications must be made consistently over the long term to produce measurable increases in organic matter.

Where herbicide strips are used, long-term organic matter inputs to the soil are often minimal because vegetation and root growth are intentionally removed. Pairing weed control with surface applications such as mulch or other organic materials helps replace those lost carbon inputs, allowing weed management while still providing the soil with an organic input.

Living Roots and the Water Holding Capacity

Vegetation between orchard rows is often viewed as competition, but when properly managed, groundcover can be an important soil health tool. Leguminous groundcovers, such as perennial peanut, can contribute biologically fixed nitrogen to the system. Living roots also provide a steady supply of organic matter to the soil.

In Florida’s sandy soils, soil health is also connected to water efficiency. According to the USDA Natural Resources Conservation Service (NRCS), each 1% increase in soil organic matter can increase the soil’s water-holding capacity by more than 20,000 gallons per acre. Healthy soil does not replace irrigation, but it can improve irrigation efficiency by helping water remain in the root zone longer and slowing down how quickly soils dry or water moves past the root zone after substantial rainfall or irrigation.

Building healthy orchard soils requires a long-term approach. Careful site preparation before planting, combined with practices that maintain soil organic matter and living roots, can improve soil function and help support productive orchards for years to come.

This hands-on program will cover key drip irrigation principles, including system design, automation, fertigation, and maintenance. Attendees can also earn a Drip Irrigator Short Course Certificate by attending the workshop and completing a brief checklist of irrigation practices. Required steps include attending the workshop on November 13th, installing and using a soil moisture sensor, and completing a short follow-up survey. Participants can choose optional activities such as checking drip system pressure, flushing irrigation lines, testing irrigation uniformity, performing a blue dye demonstration to observe water/fertilizer movement, or using an automated irrigation system to improve efficiency.

Irrigation Demonstration Support

Funding is currently available through a BMP Mini-Grant from the Florida Department of Agriculture and Consumer Services (FDACS) to help growers evaluate and improve the efficiency of their irrigation systems and practices through hands-on demonstrations. These include multiple, hands-on demonstrations designed to visualize and improve irrigation practices and system performance:

• Blue dye demonstrations: show how water moves through the soil, helping growers to understand irrigation depth and distribution within the root zone.
• Irrigation uniformity test for drip irrigation: measure how evenly water is applied across a field, identifying areas that may need system adjustments or maintenance.
• Electrical conductivity (EC) flush tests: use an EC meter to measure how long it takes for injected fertilizer or other materials to reach the end of the drip lines. It helps growers determine the proper injection time to ensure all fertilizer reaches the field evenly, improving nutrient use efficiency.

These demonstration support resources are available to all growers, whether or not they participate in the Master Irrigator Drip Irrigation Short Course Program, through June 2026. For more information, contact your local UF/IFAS Extension agent or Jay Capasso at jcapasso@ufl.edu.

Register for the Master Irrigator Drip Irrigation Short Course Program Below:

https://www.eventbrite.com/e/master-irrigator-drip-irrigation-short-course-tickets-1689226304349?aff=ebdsoporgprofile

Peanut harvest season has begun in North Florida which raises the question: when should you terminate irrigation in peanuts? Unlike corn, peanuts are an indeterminate crop, meaning plants will continue flowering and setting pods over an extended period instead of reaching maturity at the same time. Due to this growth habit, peanuts do not have a clear physiological irrigation termination point.

Irrigation in peanuts is generally beneficial until most pods have filled and the crop is approaching maturity. Keeping soils moist late in the season can reduce stress, but too much moisture may raise disease pressure. Dry conditions late in the season can cause pods to loosen and break away from their stems. In peanuts grown for seed, dry conditions can reduce seed quality if pods dry out excessively before harvest. In addition, soil type and weather conditions are important considerations, as Florida’s sandy soils dry out quickly and depending on rainfall, may require irrigation close to harvest. As of September 15, 2025, conditions in the Suwannee Valley are currently dry with little to no rain in recent weeks and no rain in the forecast. Note that conditions could change but growers should avoid shorting the crop under current conditions, as irrigation may be needed up until very close to digging.

When scheduling irrigation late in the season, it is important to consider peanut water use requirements. As shown in Image 1, water demand begins to decline around 80 days after planting. Most runner-type peanuts reach maturity around 140 days or 2500 Growing Degree Days (GDD’s), with the exception of longer-season varieties such as 12Y, which requires closer to 160 days. It is recommended to start conducting maturity checks around 120 days or 2100 GDD’s after planting.

Once you know the estimated digging date for your field, ideally based on pod-blasting methods, consider current soil moisture, the timing of your last irrigation or rainfall, the short-term weather forecast, and crop water use. Near harvest, peanuts use about 0.04 inches of water per day. In North Florida’s sandy soils, the water-holding capacity is only about 0.7 inches per foot (generally for row crops we estimate that 50% of soil water holding capacity is plant available, thus, the crop can only access about 0.35 inches per foot in most of our sandy soils), making irrigation necessary even during growth stages with lower water demand.

General late season irrigation guidelines include:

• If digging is soon and moisture is adequate, terminate irrigation.
• If digging is soon but fields are dry and no rain is expected, apply one more irrigation; if reliable rain is forecasted, hold off.
• If digging is still weeks away and fields are drying out with no rain predicted, irrigate.
• If moisture is adequate and rainfall is uncertain, monitor conditions and decide closer to digging. And, if rain comes, terminate irrigation.

Excessively dry soils at digging can increase the wear on peanut digging equipment. The abrasive nature of soil particles, especially sand, acts like sandpaper on peanut digging blades, causing them to dull and wear out faster.

It is common practice (although not recommended) to terminate irrigation once peanut digging begins. On larger farms, where peanut digging can take 30 days or more, the crop might experience water stress during this period (especially later planted fields). Although peanut water demand is reduced later in the season, the current dry conditions, which are not uncommon in September and October, can still make irrigation necessary.

In mid-August, we began receiving reports of peanut leaf spot and rust diseases from Levy to Jackson counties. It is important for growers to monitor fields, especially later planted fields around 100 days after planting (DAP), and fields that are not being scouted.

Leaf Spots

Late and early leaf spot symptoms and signs on peanut. Image credit: Nick Dufault, UF/IFAS

On PeanutRx, varieties with a leaf spot score of 20 are considered susceptible, while a score of 25 or higher indicates high susceptibility (e.g., FloRun T61, Georgia-09B, Georgia-16HO, Georgia-18RU, TUFRunner 297, and TUFRunner 511).

At the Marianna research station, both untreated and well-sprayed plots of these cultivars planted on May 7th (105 DAP) have leaf spot diseases present with ~4 to 5 weeks remaining until harvest. It is expected that rapid defoliation will occur over the next 2-3 weeks, if environmental conditions remain conducive for the pathogens, which may result in early digging of a field. As a field approaches ~50% defoliation, plan to dig within 7 days; waiting until 75% defoliation is reached results in significant pod loss due to vine and peg degradation.

Maintaining a timely and effective fungicide program is key to disease control. Products can range in their effectiveness from one disease to another, and some are most effective when positioned at specific times in the season. When spraying older peanuts (>100 DAP), pre-harvest intervals (PHI) are important factors to consider when selecting a product. Table 1 lists a few fungicides with targeted activity for leaf spots.

Table 1. Always read and follow the label. Examples only; not all-inclusive. This example lists several products that could be positioned later in the season when fields have high leaf spot incidence. *MOA stands for mode of action, meaning the site where a product affects the fungus. **Many leaf spot fungicides vary in their activity against early and late leaf spot. Under high disease risk, it is recommended to include (mix in) a protectant fungicide, especially when using older chemistries with MOA groups 3 and 11. ^Micronized sulfur products are available in both dry (powder) and liquid formulations. Refer to the product label for the exact application rate. For dry formulations, the typical range is 3–5 lbs. per acre.

Rust

Peanut rust in a field in Levy County, taken 8/20/25. Image credit: Beth Cannon.

Peanut rust is not uncommon in the eastern part of Florida but does not reach damaging levels in most years. Unfortunately, this year (2025), rust has already been found from the Suwannee Valley to the Panhandle at damaging levels. This is a situation that needs to be monitored closely, since rust can spread very rapidly. (Note: Peanut Rust was confirmed to be in peanuts at the NFREC Marianna on 8/22/25).  Most fungicide products with activity against peanut rust have a pre-harvest interval of 14 days (Table 2). However, it is important to note that some have longer intervals (e.g. 30 days). Also, for fields with severe late season peanut rust, digging prior to optimum maturity may be required to avoid significant vine health deterioration. For example, if rust is confirmed and harvest is >30 days away, consider tightening to 7 to 10-day spray intervals; if vine health declines and maturity is close, prioritize digging over chasing infections.

Table 2. This is not an all-inclusive list, but it shows several products with effective activity for peanut rust management.

Introduction

North Florida’s Suwannee Valley is an agriculturally productive region for crops, including corn, peanuts, watermelon, and carrots. The region is also home to the highest concentrations of freshwater springs in the world, which serve as major tourist and recreational sites.

The region has very sandy soils, so water and the nitrates dissolved in it percolate quickly through the root zone, making it difficult to keep nutrients available for crops and out of the groundwater. Meeting water quality targets, such as those established through basin management action plans for the Santa Fe and Suwannee River, has become an important issue for the agricultural industry and state regulators.

UF/IFAS scientists at the North Florida Research and Education Center–Suwannee Valley launched in 2018 the Sod-Based Rotation Project, funded by the Florida Department of Agriculture and Consumer Services. Over 16 years, the study will compare five zones under a center-pivot irrigation system. Each zone follows a distinct crop rotation, ranging from the conventional peanut-corn cycle to a peanut-corn-carrot rotation. Two of the rotations also include a two-year phase of bahiagrass pasture with cattle grazing before the rotation returns to row crops.

By tracking soil nitrogen at multiple depths, plant uptake, yields, and modeling results, the project will demonstrate how much a sod rotation and the implementation of best management practices increase yield and conserve nitrate in the root zone.

After just a single 4-year cycle, the rotations including 2 years of sod are already demonstrating improvement to the soil at the project site (Acharya & Sharma, 2025):

• Increased water-holding capacity: in the top six inches of soil. In North Florida’s quick-drying sandy soils, that added water-holding capacity means moisture from rainfall and irrigation events last longer in the soil, increasing the field’s drought resilience.

• Higher aggregate stability: a key indicator of physical soil health.
• Evidence of less deep percolation: suggests less nitrate leaching potential.

The project has just entered Phase Two, where best management practices, including split nitrogen applications, controlled-release fertilizers, efficient fertilizer placement methods such as banding, and soil moisture sensor-guided irrigation, are included in each rotation.

Take Away for North Florida Farmers

Sod-based rotations provide many benefits, including reducing plant disease and pest pressure on row crops, thereby boosting yields. Perennial grasses also have deep roots that can build soil organic matter over time, increasing soil water-holding capacity and nutrient content. Grazing offers additional advantages for soil health by increasing rooting, cycling nutrients, and enriching the land’s microbial diversity. Growers should take into consideration that perennial grasses produce considerable residue and are challenging to kill. Generally, it is recommended to apply herbicide to the Bahia grass and overseed with a winter cover crop in the fall before transitioning to a row crop, such as peanuts or corn. These steps will allow time for the Bahia grass residue to break down.

The Dry Corners

The research sites “dry corners” refer to the areas surrounding the center pivot irrigation system that do not receive irrigation. They have become valuable sites for extension forage demonstrations. Local County Extension agents Paulette Tomlinson from UF/IFAS Extension Columbia County and Erin Dasher from UF/IFAS Extension Suwannee County have led several educational field day events to teach producers about forage, grazing, weed, and nutrient management.

References

Acharya B and Sharma V (2025) Comparative analysis of soil and water dynamics in conventional and sod-based crop rotation in Florida. Front. Agron. 7:1552425. doi: 10.3389/fagro.2025.1552425

Introduction

Effective management of irrigation and fertigation is crucial to optimize blueberry production. When used together, especially with drip systems, water and nutrients are applied directly to the root zone, improving plant uptake while reducing nutrient losses from runoff or leaching. Spoon-feeding nutrients through fertigation enables growers to time fertilizer applications to match the crop demand, improving nutrient use efficiency and minimizing environmental impact. Blueberries thrive in acidic soils and prefer ammonium-based nitrogen fertilizers. Blueberries struggle to use the nitrogen in the nitrate form efficiently.  This is due to their low levels of nitrate reductase, the key enzyme required to convert nitrate into a usable form of nitrogen for the plant (Claussen & Lenz 1999).

Fundamentals of Fertigation

Fertigation systems work by mixing fertilizer into irrigation water and sending it through drip lines or other irrigation methods. Injectors move the fertilizer from a storage tank into the irrigation system, either manually or using automated equipment. One important thing to consider is how long it takes fertilizer to reach the farthest point in the field to determine how long the irrigation system needs to be run to completely flush out the fertilizer. This affects how evenly fertilizer is applied across the field. Fertigation systems require regular maintenance to prevent clogging, corrosion, or backflow contamination. Only water-soluble fertilizers should be used, and the system must be properly calibrated and maintained to work efficiently.

Fertilizer Injectors:

• Venturi Injectors: Affordable and simple, but cause pressure loss and offer limited precision.
• Positive Displacement Pumps: Provide accurate, adjustable injections regardless of changes in water pressure which is ideal for larger systems. Higher cost and power required.
• Pressure Differential Tanks: Inexpensive and easy to install, but fertilizer concentration declines over time, limiting consistency and scalability.
• Fertilizer Storage Tanks: Should be corrosion-resistant and appropriately sized. Multiple tanks may be needed to separate incompatible fertilizers. Use a jar test to check fertilizer compatibility before mixing.
• Backflow Prevention Devices: Legally required to protect water sources from contamination. In Florida, small drip irrigation systems used for fertigation or chemigation on blueberry farms must include backflow protection to prevent contamination of the water supply. Chemicals should never be injected into the irrigation system before the pump, because this can damage equipment or contaminate the water source. All chemical applications must follow label instructions (Bayabil et al., 2020).
• Filters: Remove particulates to prevent emitter clogging. Use screen, disc, or sand filters based on the water quality. Screen filters are good for filtering mineral particles while disc filters are preferred for filtering organic particles. Fertilizer injection should occur upstream of the filters and downstream of the backflow prevention device.
• Pressure Regulators and Gauges: Maintain consistent pressure within the emitter’s operating range (often for drip somewhere around 8 – 15 psi) to ensure uniform nutrient and water application. For larger operations, positive displacement pumps are recommended for consistent injection.
• Water flow meter: Know the water flow and pressure. Flow meters can help you record your injectors’ flow rate. Reduced flow rates but high pressure in the system could indicate a clog. Alternatively, situations with high flow rates and low pressure could be a signal that may have a leak in the irrigation system.

Fertilizers for Blueberry Fertigation

Blueberries require macronutrients (N, P, K, Ca, Mg, S) and micronutrients (Fe, Mn, B, Zn, Cu, Mo). Nutrient demand changes by growth stage, establishment, vegetative growth, flowering, fruiting, and post-harvest. Use water-soluble nitrogen, phosphorus, and potassium fertilizers suitable for acid-loving plants. Avoid chloride-based sources and incompatible mixes of fertilizer. When in doubt, conduct a jar to test to determine compatibility.

Emitter Clogging:

Emitter clogging can be caused by liquid fertilizer coming out of solution, algae growth, high pH, or mineral precipitation like iron and manganese. To reduce the risk of clogging, use fertilizers that are soluble and compatible. Water may need to be acidified, and chlorine can be injected to manage algae. Choosing clog-resistant emitters and flushing the system regularly are good maintenance practices. Flushing can be done manually or with automatic flush valves placed at the end of the drip tape to reduce maintenance time. Filters should be installed to remove particles from the water before they reach the emitters.

Uneven Nutrient Distribution:

Uneven nutrient distribution can result from poor system design, inconsistent water pressure, or fertilizer solutions that are not properly mixed or dissolved before injection. To improve uniformity, use pressure compensating emitters, which provide a consistent output even with pressure changes (but generally cost more).

Conclusion and Recommendations

Fertigation is an effective way to improve blueberry yields, enhance nutrient and water use efficiency, as well as minimize environmental impact. To maximize benefit, growers should assess their existing irrigation system and water quality. Use water-soluble, ammonium-based fertilizers, and ensure the system includes filters and approved backflow prevention devices. Develop a fertigation schedule based on crop growth stages. Regularly flush the system to prevent clogging. With proper irrigation system design and management, fertigation supports healthier plants, better fruit quality, and more sustainable production. If you need help with any part of the fertigation process, reach out to your local county extension agent for support.

References

Bayabil, H. K., Migliaccio, K. W., Crane, J. H., Olczyk, T., & Wang, Q. (2020). Regulations and guidelines for chemigation (AE542). University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Extension. https://edis.ifas.ufl.edu/publication/AE542

Claussen, W., & Lenz, F. (1999). Effect of ammonium or nitrate nutrition on net photosynthesis, growth, and activity of the enzymes nitrate reductase and glutamine synthetase in blueberry, raspberry and strawberry. Plant and Soil, 208, 95–102. https://doi.org/10.1023/A:1004457720197

Understanding Irrigation Distribution Uniformity (DU) and Efficiency: Why It Matters for Growers

Irrigation is an important tool for maximizing crop yield, but to truly optimize water use, it’s important to understand two key concepts: Distribution Uniformity (DU) and Irrigation Efficiency. Here is a breakdown of each term’s meaning and how it impacts your operation.

What is Distribution Uniformity (DU)?

Distribution uniformity meaures how evenly water is distributed across your field. Achieving a DU of 90% is possible for both center pivot and linear overhead irrigation systems. This means that 90% of your field will receive water in a uniform, even manner, which is crucial for minimizing water waste and ensuring your crops receive the right amount of moisture. In the Suwannee Valley, mobile irrigation labs offer free evaluations of irrigation systems to help growers assess their DU.

The catch can method is often used to calculate DU. This method involves measuring the water collected in various cans placed across the field, with the average of the lowest 25% of the measurements divided by the total average depth of water applied over the entire field.

Benefits of Maintaining Good DU

When you maintain good DU, you reap several benefits:

• Simpler Irrigation Scheduling: You don’t need to irrigate the driest parts of the field as much, saving time and water.
• Reduced Field Variability: More uniform water application means fewer pockets of dry or overwatered areas, making your field more consistent.
• More Accurate Soil Sensor Readings: When variability is reduced, soil moisture sensors give you a more accurate picture of water availability across the entire field.

Distribution uniformity also becomes essential if injecting liquid fertilizer through your irrigation system. With more even water distribution, the fertilizer will be applied more uniformly, resulting in better crop uptake and reduced crop growth variability throughout the field.

Factors That Impact DU

Several factors affect the uniformity and efficiency of your irrigation system. Flow rate variability can result from pressure differences, friction losses, or changes in field elevation. Pressure variations in regulators, which control water pressure in the irrigation system, can cause uneven water flow to sprinklers, leading to inconsistent water distribution. This can affect sprinkler performance and spray patterns, increasing system wear and energy costs. Stable pressure is essential for uniform irrigation. Nozzle wear or clogging creates uneven water distribution, while improper sprinkler spacing or design issues can also lead to variations in uniformity. End gun alignment issues can be problematic when water application from the end gun overlaps areas already covered by overhead sprinklers, leading to uneven water distribution. Environmental factors like wind and plant interference can disrupt water application through sprinklers. Operational practices, such as uneven water application during system startup or shutdown and pipe diameter variations, can also cause inconsistencies. Edge effects, where sprinklers overlap at the field edges, can result in less uniform water distribution.

Irrigation Efficiency: How Does it Differ?

While DU focuses on how evenly water is distributed, irrigation efficiency refers to how much of the water you applied is beneficially used by the crop. The equation looks like this:

Efficiency = Water Beneficially Used / Total Water Applied

For growers in the Southeast, irrigation efficiency generally refers to how much water is beneficially used to meet crop evapotranspiration (ET) or the crop’s water needs. We typically don’t need to worry about leaching salts, which could be a beneficial use of water in arid regions with salinity issues. Other potential beneficial uses of water application, though less common than meeting ET, include climate control or promoting weed germination (to be controlled later through management).

Efficiency can be challenging to measure accurately because it depends on how much water reaches crop roots for uptake. In practice, soil moisture sensors can help measure how much water reaches the root zone, providing insight into your irrigation scheduling and system efficiency.

Using Soil Moisture Sensors and DU and Efficiency

Soil moisture sensors are valuable tools for assessing the efficiency of your irrigation scheduling and system performance. To ensure accurate data, placing these sensors in representative areas of the field is crucial. Placing sensors in locations with poor DU can result in data that does not accurately reflect the field’s overall water distribution. This can lead to incorrect conclusions about irrigation scheduling and system efficiency.

Mobile Irrigation Labs: A Useful Resource for Growers in Florida and Georgia

For growers in Florida, mobile irrigation labs are an excellent resource that can help you evaluate the performance of your center pivot and linear move irrigation systems, providing valuable information on DU and efficiency. In Georgia, UGA Cooperative Extension performs evaluations of client’s center pivot and linear move irrigation systems. With professional evaluations, growers can identify areas where their irrigation system needs improvement. Agricultural cost-share opportunities may be available through the Florida Department of Agriculture and Consumer Services or local water management districts to help upgrade irrigation systems if issues are identified for those enrolled in the FDACS BMP program. In Georgia, opportunities are available through USDA NRCS programs. For more information on your local mobile irrigation lab, see the link below: https://www.fdacs.gov/Water/Mobile-Irrigation-Labs.

Understanding Irrigation Distribution Uniformity (DU) and Efficiency: Why It Matters for Growers

Irrigation is an important tool for maximizing crop yield, but to truly optimize water use, it’s important to understand two key concepts: Distribution Uniformity (DU) and Irrigation Efficiency. Here is a breakdown of each term’s meaning and how it impacts your operation.

What is Distribution Uniformity (DU)?

Distribution uniformity meaures how evenly water is distributed across your field. Achieving a DU of 90% is possible for both center pivot and linear overhead irrigation systems. This means that 90% of your field will receive water in a uniform, even manner, which is crucial for minimizing water waste and ensuring your crops receive the right amount of moisture. In the Suwannee Valley, mobile irrigation labs offer free evaluations of irrigation systems to help growers assess their DU.

The catch can method is often used to calculate DU. This method involves measuring the water collected in various cans placed across the field, with the average of the lowest 25% of the measurements divided by the total average depth of water applied over the entire field.

Benefits of Maintaining Good DU

When you maintain good DU, you reap several benefits:

• Simpler Irrigation Scheduling: You don’t need to irrigate the driest parts of the field as much, saving time and water.
• Reduced Field Variability: More uniform water application means fewer pockets of dry or overwatered areas, making your field more consistent.
• More Accurate Soil Sensor Readings: When variability is reduced, soil moisture sensors give you a more accurate picture of water availability across the entire field.

Distribution uniformity also becomes essential if injecting liquid fertilizer through your irrigation system. With more even water distribution, the fertilizer will be applied more uniformly, resulting in better crop uptake and reduced crop growth variability throughout the field.

Factors That Impact DU

Several factors affect the uniformity and efficiency of your irrigation system. Flow rate variability can result from pressure differences, friction losses, or changes in field elevation. Pressure variations in regulators, which control water pressure in the irrigation system, can cause uneven water flow to sprinklers, leading to inconsistent water distribution. This can affect sprinkler performance and spray patterns, increasing system wear and energy costs. Stable pressure is essential for uniform irrigation. Nozzle wear or clogging creates uneven water distribution, while improper sprinkler spacing or design issues can also lead to variations in uniformity. End gun alignment issues can be problematic when water application from the end gun overlaps areas already covered by overhead sprinklers, leading to uneven water distribution. Environmental factors like wind and plant interference can disrupt water application through sprinklers. Operational practices, such as uneven water application during system startup or shutdown and pipe diameter variations, can also cause inconsistencies. Edge effects, where sprinklers overlap at the field edges, can result in less uniform water distribution.

Irrigation Efficiency: How Does it Differ?

While DU focuses on how evenly water is distributed, irrigation efficiency refers to how much of the water you applied is beneficially used by the crop. The equation looks like this:

Efficiency = Water Beneficially Used / Total Water Applied

For growers in the Southeast, irrigation efficiency generally refers to how much water is beneficially used to meet crop evapotranspiration (ET) or the crop’s water needs. We typically don’t need to worry about leaching salts, which could be a beneficial use of water in arid regions with salinity issues. Other potential beneficial uses of water application, though less common than meeting ET, include climate control or promoting weed germination (to be controlled later through management).

Efficiency can be challenging to measure accurately because it depends on how much water reaches crop roots for uptake. In practice, soil moisture sensors can help measure how much water reaches the root zone, providing insight into your irrigation scheduling and system efficiency.

Using Soil Moisture Sensors and DU and Efficiency

Soil moisture sensors are valuable tools for assessing the efficiency of your irrigation scheduling and system performance. To ensure accurate data, placing these sensors in representative areas of the field is crucial. Placing sensors in locations with poor DU can result in data that does not accurately reflect the field’s overall water distribution. This can lead to incorrect conclusions about irrigation scheduling and system efficiency.

Mobile Irrigation Labs: A Useful Resource for Growers in Florida and Georgia

For growers in Florida, mobile irrigation labs are an excellent resource that can help you evaluate the performance of your center pivot and linear move irrigation systems, providing valuable information on DU and efficiency. In Georgia, UGA Cooperative Extension performs evaluations of client’s center pivot and linear move irrigation systems. With professional evaluations, growers can identify areas where their irrigation system needs improvement. Agricultural cost-share opportunities may be available through the Florida Department of Agriculture and Consumer Services or local water management districts to help upgrade irrigation systems if issues are identified for those enrolled in the FDACS BMP program. In Georgia, opportunities are available through USDA NRCS programs. For more information on your local mobile irrigation lab, see the link below: https://www.fdacs.gov/Water/Mobile-Irrigation-Labs.

This rule impacts water withdrawals in the North Florida Regional Water Supply Partnership area, covering counties such as Alachua, Baker, Bradford, Clay, Columbia, Duval, Flagler, Gilchrist, Hamilton, Nassau, Putnam, St. Johns, Suwannee, and Union.

The proposed rule aims to update the MFLs for the Lower Santa Fe and Ichetucknee Rivers and associated Priority Springs. The updated MFLs will serve as the basis for regulating water withdrawals in the consumptive use permit process. Key aspects of the proposed rule include:

Modification of Existing Permits:

• Existing consumptive use permits in the North Florida Regional Water Supply Partnership area will be modified to meet the new MFLs, potentially leading to changes or reductions in permitted water allocations.
• The modification process will incorporate new conditions into existing permits, including requirements related to offsetting impacts and water conservation.

Impact Evaluation: The proposed rule requires a thorough evaluation of the impact of all water withdrawals on MFL compliance points. These three MFL compliance points are river gages located at the Santa Fe River near Fort White, Santa Fe River at US HWY 441 near High Springs and Ichetucknee River at HWY 27 near Hildreth. The first gage near Fort White currently meets the required MFLs, while the gages near High Springs and Hildreth are in recovery, indicating their flow levels are below the required MFLs.

Permit holders are responsible for addressing their contributions to any identified impacts. This includes demonstrating that their water use will not worsen conditions at recovering MFL compliance points. If a permittee impacts multiple MFL compliance points that are in a state of recovery, their offset requirements will be determined based on the compliance point where their impact is greatest.

Calculating Offset: A permittee’s offset is calculated by determining their proportionate share for the recovering MFL compliance point. This is done by dividing the permittee’s individual impact (Ip) by the total impact at the MFL compliance point (It), using baseline average water uses from 2014-2018, and then multiplying by the 2014-2018 Net Flow Deficit (Infd).

For example, if a permittee’s water use reduces the flow at a recovering MFL compliance point by 1 cubic feet per second (cfs), and the total impact from all water uses (baseline 2014-2018) is 10 cfs, with a Net Flow Deficit of 6.3 cfs, the permittee’s required offset would be calculated as follows:

Proportionate Share = (Individual Impact (Ip) / Total Impact (It)) × Net Flow Deficit of the recovering MFL compliance point (Infd).

Calculation: (1 cfs / 10 cfs) × 6.3 cfs = 0.63 cfs.

Offsetting Impacts: Water users may be required to implement offset projects to mitigate any adverse effects their withdrawals have on recovering MFL compliance points.

• Permittees can implement various types of projects to offset impacts, including water resource or supply development projects, retirement of water use, or other means that increase flow to MFL compliance points. These projects are designed to counterbalance the effects of water withdrawals. These could be individual or regional offset projects. One example of a regional offset project is the Black Creek Water Resource Development Project managed by St. Johns River Water Management District.
• Offset Credits: Water users who successfully implement offset projects may receive offset credits. These credits are applied to their permits, allowing continued water use while ensuring that the overall impact on the recovering MFL compliance points is neutral or positive. However, if an offset project fails to deliver the anticipated benefits, the permit holder may need to provide an equivalent replacement offset or face a reduction in their water use.
• This offset must be implemented as soon as practicable, but no later than 20 years from the rule’s effective date. If you increase your water use beyond what was recorded during the base condition period, you will also need to offset the new impact.

Water Conservation Requirements:

Irrigation System Maintenance and Evaluation: Agricultural permittees must maintain their irrigation systems to meet specific minimum distribution uniformity (DU) standards, which vary by system type. Distribution uniformity measures how evenly water is applied across an irrigated area to ensure efficient water use. Micro-drip systems should achieve a DU of 80–90%, micro-spray systems 75–85%, low-pressure center pivot or lateral move systems 75–85%, standard center pivot systems with end guns 65–75%, and in-place overhead sprinklers 70–75%. Mobile Irrigation Labs typically estimate DU during free evaluations for growers. To ensure compliance with these standards, permittees must submit evaluations of their systems, and there is interest in establishing an additional mobile irrigation lab in the Suwannee Valley if needed to help agricultural producers comply.

Transition to More Efficient Systems: For irrigation methods like seepage irrigation, permittees must submit a plan to transition to more efficient systems within the duration of the permit. This transition plan should outline how and when the improvements will be made, ensuring that water use is minimized and efficiency is maximized.

Water Conservation Measures: The rule introduces a tiered system for water conservation practices, each offering varying levels of water-saving potential. Agricultural permittees must demonstrate that they are implementing high-level water conservation measures or propose alternative methods with similar effectiveness. Key practices include using advanced irrigation technologies like soil moisture sensors and automated systems, converting to more efficient irrigation methods, and implementing strategies like conservation tillage and tailwater recovery (which capture and reuse runoff water from irrigation), along with Alternative Water Supply projects, which are prioritized due to their potential for water savings.

Public Comment: The rule is still in the development phase, and there will be opportunities to provide input. A public comment period is open until October 31st, 2024.

You can submit comments via email to: OWP_rulemaking@floridadep.gov

More Information

This rule impacts water withdrawals in the North Florida Regional Water Supply Partnership area, covering counties such as Alachua, Baker, Bradford, Clay, Columbia, Duval, Flagler, Gilchrist, Hamilton, Nassau, Putnam, St. Johns, Suwannee, and Union.

The proposed rule aims to update the MFLs for the Lower Santa Fe and Ichetucknee Rivers and associated Priority Springs. The updated MFLs will serve as the basis for regulating water withdrawals in the consumptive use permit process. Key aspects of the proposed rule include:

Modification of Existing Permits:

• Existing consumptive use permits in the North Florida Regional Water Supply Partnership area will be modified to meet the new MFLs, potentially leading to changes or reductions in permitted water allocations.
• The modification process will incorporate new conditions into existing permits, including requirements related to offsetting impacts and water conservation.

Impact Evaluation: The proposed rule requires a thorough evaluation of the impact of all water withdrawals on MFL compliance points. These three MFL compliance points are river gages located at the Santa Fe River near Fort White, Santa Fe River at US HWY 441 near High Springs and Ichetucknee River at HWY 27 near Hildreth. The first gage near Fort White currently meets the required MFLs, while the gages near High Springs and Hildreth are in recovery, indicating their flow levels are below the required MFLs.

Permit holders are responsible for addressing their contributions to any identified impacts. This includes demonstrating that their water use will not worsen conditions at recovering MFL compliance points. If a permittee impacts multiple MFL compliance points that are in a state of recovery, their offset requirements will be determined based on the compliance point where their impact is greatest.

Calculating Offset: A permittee’s offset is calculated by determining their proportionate share for the recovering MFL compliance point. This is done by dividing the permittee’s individual impact (Ip) by the total impact at the MFL compliance point (It), using baseline average water uses from 2014-2018, and then multiplying by the 2014-2018 Net Flow Deficit (Infd).

For example, if a permittee’s water use reduces the flow at a recovering MFL compliance point by 1 cubic feet per second (cfs), and the total impact from all water uses (baseline 2014-2018) is 10 cfs, with a Net Flow Deficit of 6.3 cfs, the permittee’s required offset would be calculated as follows:

Proportionate Share = (Individual Impact (Ip) / Total Impact (It)) × Net Flow Deficit of the recovering MFL compliance point (Infd).

Calculation: (1 cfs / 10 cfs) × 6.3 cfs = 0.63 cfs.

Offsetting Impacts: Water users may be required to implement offset projects to mitigate any adverse effects their withdrawals have on recovering MFL compliance points.

• Permittees can implement various types of projects to offset impacts, including water resource or supply development projects, retirement of water use, or other means that increase flow to MFL compliance points. These projects are designed to counterbalance the effects of water withdrawals. These could be individual or regional offset projects. One example of a regional offset project is the Black Creek Water Resource Development Project managed by St. Johns River Water Management District.
• Offset Credits: Water users who successfully implement offset projects may receive offset credits. These credits are applied to their permits, allowing continued water use while ensuring that the overall impact on the recovering MFL compliance points is neutral or positive. However, if an offset project fails to deliver the anticipated benefits, the permit holder may need to provide an equivalent replacement offset or face a reduction in their water use.
• This offset must be implemented as soon as practicable, but no later than 20 years from the rule’s effective date. If you increase your water use beyond what was recorded during the base condition period, you will also need to offset the new impact.

Water Conservation Requirements:

Irrigation System Maintenance and Evaluation: Agricultural permittees must maintain their irrigation systems to meet specific minimum distribution uniformity (DU) standards, which vary by system type. Distribution uniformity measures how evenly water is applied across an irrigated area to ensure efficient water use. Micro-drip systems should achieve a DU of 80–90%, micro-spray systems 75–85%, low-pressure center pivot or lateral move systems 75–85%, standard center pivot systems with end guns 65–75%, and in-place overhead sprinklers 70–75%. Mobile Irrigation Labs typically estimate DU during free evaluations for growers. To ensure compliance with these standards, permittees must submit evaluations of their systems, and there is interest in establishing an additional mobile irrigation lab in the Suwannee Valley if needed to help agricultural producers comply.

Transition to More Efficient Systems: For irrigation methods like seepage irrigation, permittees must submit a plan to transition to more efficient systems within the duration of the permit. This transition plan should outline how and when the improvements will be made, ensuring that water use is minimized and efficiency is maximized.

Water Conservation Measures: The rule introduces a tiered system for water conservation practices, each offering varying levels of water-saving potential. Agricultural permittees must demonstrate that they are implementing high-level water conservation measures or propose alternative methods with similar effectiveness. Key practices include using advanced irrigation technologies like soil moisture sensors and automated systems, converting to more efficient irrigation methods, and implementing strategies like conservation tillage and tailwater recovery (which capture and reuse runoff water from irrigation), along with Alternative Water Supply projects, which are prioritized due to their potential for water savings.

Public Comment: The rule is still in the development phase, and there will be opportunities to provide input. A public comment period is open until October 31st, 2024.

You can submit comments via email to: OWP_rulemaking@floridadep.gov

More Information

Watermelon production relies on precise irrigation management for optimal growth. Getting the duration and frequency of irrigation right is crucial for using water efficiently and achieving a successful harvest.

Understanding Irrigation Duration

Based on our experience, utilizing drip tape with a flow rate of 0.4 gallons per 100 feet per minute, it’s important not to irrigate longer than a duration of 1 – 1.5 hours in any single irrigation event (do not count the time it takes to pressurize the drip irrigation system in the total run time). Since watermelon roots typically extend to depths of 12 – 15 inches, irrigating longer than 1.5 hours at this flow rate leads to water leaching below the root zone in our sandy Suwannee Valley soils. When water leaches below the root zone it is no longer useful to the watermelon crop and risks leaching nutrients.

Irrigation Frequency: Twice (or thrice) is Nice

Instead of irrigating once a day for 3 or 4 hours a strategy of shorter, more frequent, irrigation events is more beneficial. Dividing daily irrigation into two 1 – 1.5 hour sessions throughout the day better aligns with the watermelon’s ability to absorb water in the root zone; this strategy also minimizes the risk of leaching. Some growers may benefit from irrigating even more than two events a day. See image 1 below of soil moisture sensor data showing how a watermelon grower increased the amount of irrigation water in the root zone by switching from two long irrigation events to three shorter irrigation events daily. As a result, he was able to better maintain a stable level of soil moisture in the root zone.

Tailoring Irrigation to Different Drip Tape Flow Rates

Not all drip tape flow rates are the same. With reduced flow rates, it takes longer to saturate the watermelon root zone adequately, extending the necessary irrigation time. For growers using lower drip flow rates, such as those ranging from 0.22 to 0.25 gallons per 100 feet per minute, growers should avoid irrigating more than 2.7 hours (approximately 2 hours and 40 minutes).

How Can I Tell if I am Irrigating Correctly?

A soil moisture sensor can help you determine if your irrigation event is too long or too short. With a soil moisture sensor containing sensors at various depths, you can run an irrigation event and determine how deep sensors record increased moisture content from the irrigation event. If irrigation is not reaching the 12-15 inch depths you are not sufficiently irrigating the entire watermelon root zone. This is more problematic later in the season when roots are fully grown, and temperature/evapotranspiration have increased. Large increases in moisture content below the 12-15 inch depth indicate that water is being wasted and moving nutrients below the root zone. Blue dye can also be used to determine how deep water percolates in the soil via an irrigation event.

Although not commonly produced in Florida, Brussels sprouts (Brassica Oleracea L) are increasingly grown commercially in Columbia County, FL. In the USA, Brussels sprout production occurs primarily in California and New York but can be grown over the winter months in Florida. Optimal temperature range for Brussels sprouts is about 58 – 60°F. Planting date in Florida, generally occurs between October and December which provides a cooler climate. Harvest usually occurs March – April. While Brussels sprouts can withstand frost and freezing conditions, temperatures significantly below freezing (32°F) can damage Brussels sprouts.

Planting and soil conditions:

The distance between plants is generally 15-24 inches and distance between rows is 24-40 inches. Brussels sprouts should be grown in well-drained soil conditions with target pH of 6.5. UF/IFAS fertilizer recommendations are the same for Brussels sprouts, broccoli, and cauliflower. The recommended nitrogen fertilizer rate is 175 lbs. per acre. UF/IFAS guidelines for petiole sap testing in Brussels sprouts do not exist and based on limited testing during the 2022 season do not reliably compare to other similar crops like broccoli. UF/IFAS petiole sap testing guidelines do exist for broccoli but only for nitrate-nitrogen levels, which I am noting because some growers plan on planting broccoli in the same field as Brussels sprouts. Otherwise, plant tissue sampling is the most reliable method to determine Brussels sprouts nutrient concentrations during the growing season. Boron is an important micro-nutrient for Brussels sprouts and broccoli especially in sandy North Florida soils where it is often deficient due to the mobility of boron in the soil. In situations where boron is deficient, an application of 1.5 lbs. of boron per acre is recommended.

Pre- and post-emergent herbicide options:

Preemergent or pretransplant herbicide options include glyphosate for pre-transplant burndown and S-metolachlor (Dual Magnum, may require an indemnification agreement). Postemergence or posttransplant options include pendimethalin (Prowl, applied at the base of the crop within three days of transplanting) and glyphosate (applied only to row middles) (Wells et al. 2023).

Varieties and pest management:

Brussels sprouts varieties include ‘Jade Cross’ or ‘Royal Marvel’ which have an 85-day maturity. While, ‘Long Island Improved’ (an open pollinated variety), ‘Prince Marvel’, and ‘Valiant’ have a 90-day maturity (Westerfield 2022). Brussels sprouts can be planted from seed or by transplant. Common insect pests include loopers, imported cabbage worms, and aphids (Stephens 2018). Nematodes can also be a significant problem in Florida sandy soils. The most problematic plant parasitic nematodes in Florida for cole crops such as Brussels sprouts include root-knot nematodes (Meloidogyne spp.), sting nematode (Belonolaimus longicaudatus), stubby-root nematodes (Nanidorus minor), and awl nematodes (Dolichorus spp.) (Grabau & Noling 2021). Crop rotation and use of nematicides should be considered for nematode management. Nematicides options for Brussels sprouts include gaseous soil fumigants utilized prior to planting or liquid products such as Velum (fluopyram) applied at planting. The UF/IFAS nematode assay lab can be used to assess nematode populations in fields prior to planting. Plant diseases such as downy mildew, Fusarium wilt, blackleg, and black rot can be problematic in Brussels sprouts production (Westerfield 2022; Stephens 2018). Brussels sprouts should be harvested when they are full sized and firm prior to turning tough or yellow. Harvest of the earliest Brussels sprouts located at the lower section of the plant occurs first about three months after planting (Stephens 2018).

Storage

The ideal storage conditions of Brussel Sprouts post-harvest are under refrigerated conditions maintaining a temperature of 32 – 34°F and relative humidity of 90 – 95% (Stephens 2018).

References:

Grabau, Z. J., & Noling, J. W. (2021). Nematode Management in Cole Crops: NG024/ENY024, rev. 11/2020. University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS, 13-13. Retrieved from https://edis.ifas.ufl.edu/publication/NG024

Stephens, J. M. (2018). Brussels Sprouts—Brassica Oleracea L. (Gemmifera Group): HS567. University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS. Retrieved from https://edis.ifas.ufl.edu/publication/MV034

Wells, B., Smith, H. A., Zotarelli, L., Dittmar, P. J., Dufault, N. S., Desaeger, J., & Wang, Q. (2023). Cole Crop Production: Vegetable Production Handbook Chapter. 6, CV122/HS724, University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS. Retrieved from https://edis.ifas.ufl.edu/publication/CV122

Westerfield, B. (2022). Home Garden Brussels Sprouts. Circular 1069. University of Georgia Extension. Retrieved from https://extension.uga.edu/publications/detail.html?number=C1069&title=home-garden-brussels-sprouts

Although not commonly produced in Florida, Brussels sprouts (Brassica Oleracea L) are increasingly grown commercially in Columbia County, FL. In the USA, Brussels sprout production occurs primarily in California and New York but can be grown over the winter months in Florida. Optimal temperature range for Brussels sprouts is about 58 – 60°F. Planting date in Florida, generally occurs between October and December which provides a cooler climate. Harvest usually occurs March – April. While Brussels sprouts can withstand frost and freezing conditions, temperatures significantly below freezing (32°F) can damage Brussels sprouts.

Planting and soil conditions:

The distance between plants is generally 15-24 inches and distance between rows is 24-40 inches. Brussels sprouts should be grown in well-drained soil conditions with target pH of 6.5. UF/IFAS fertilizer recommendations are the same for Brussels sprouts, broccoli, and cauliflower. The recommended nitrogen fertilizer rate is 175 lbs. per acre. UF/IFAS guidelines for petiole sap testing in Brussels sprouts do not exist and based on limited testing during the 2022 season do not reliably compare to other similar crops like broccoli. UF/IFAS petiole sap testing guidelines do exist for broccoli but only for nitrate-nitrogen levels, which I am noting because some growers plan on planting broccoli in the same field as Brussels sprouts. Otherwise, plant tissue sampling is the most reliable method to determine Brussels sprouts nutrient concentrations during the growing season. Boron is an important micro-nutrient for Brussels sprouts and broccoli especially in sandy North Florida soils where it is often deficient due to the mobility of boron in the soil. In situations where boron is deficient, an application of 1.5 lbs. of boron per acre is recommended.

Pre- and post-emergent herbicide options:

Preemergent or pretransplant herbicide options include glyphosate for pre-transplant burndown and S-metolachlor (Dual Magnum, may require an indemnification agreement). Postemergence or posttransplant options include pendimethalin (Prowl, applied at the base of the crop within three days of transplanting) and glyphosate (applied only to row middles) (Wells et al. 2023).

Varieties and pest management:

Brussels sprouts varieties include ‘Jade Cross’ or ‘Royal Marvel’ which have an 85-day maturity. While, ‘Long Island Improved’ (an open pollinated variety), ‘Prince Marvel’, and ‘Valiant’ have a 90-day maturity (Westerfield 2022). Brussels sprouts can be planted from seed or by transplant. Common insect pests include loopers, imported cabbage worms, and aphids (Stephens 2018). Nematodes can also be a significant problem in Florida sandy soils. The most problematic plant parasitic nematodes in Florida for cole crops such as Brussels sprouts include root-knot nematodes (Meloidogyne spp.), sting nematode (Belonolaimus longicaudatus), stubby-root nematodes (Nanidorus minor), and awl nematodes (Dolichorus spp.) (Grabau & Noling 2021). Crop rotation and use of nematicides should be considered for nematode management. Nematicides options for Brussels sprouts include gaseous soil fumigants utilized prior to planting or liquid products such as Velum (fluopyram) applied at planting. The UF/IFAS nematode assay lab can be used to assess nematode populations in fields prior to planting. Plant diseases such as downy mildew, Fusarium wilt, blackleg, and black rot can be problematic in Brussels sprouts production (Westerfield 2022; Stephens 2018). Brussels sprouts should be harvested when they are full sized and firm prior to turning tough or yellow. Harvest of the earliest Brussels sprouts located at the lower section of the plant occurs first about three months after planting (Stephens 2018).

Storage

The ideal storage conditions of Brussel Sprouts post-harvest are under refrigerated conditions maintaining a temperature of 32 – 34°F and relative humidity of 90 – 95% (Stephens 2018).

References:

Grabau, Z. J., & Noling, J. W. (2021). Nematode Management in Cole Crops: NG024/ENY024, rev. 11/2020. University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS, 13-13. Retrieved from https://edis.ifas.ufl.edu/publication/NG024

Stephens, J. M. (2018). Brussels Sprouts—Brassica Oleracea L. (Gemmifera Group): HS567. University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS. Retrieved from https://edis.ifas.ufl.edu/publication/MV034

Wells, B., Smith, H. A., Zotarelli, L., Dittmar, P. J., Dufault, N. S., Desaeger, J., & Wang, Q. (2023). Cole Crop Production: Vegetable Production Handbook Chapter. 6, CV122/HS724, University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS. Retrieved from https://edis.ifas.ufl.edu/publication/CV122

Westerfield, B. (2022). Home Garden Brussels Sprouts. Circular 1069. University of Georgia Extension. Retrieved from https://extension.uga.edu/publications/detail.html?number=C1069&title=home-garden-brussels-sprouts

In North Florida field corn production, starter fertilizers commonly include liquid blends such as 28-0-0-5 (urea ammonium nitrate and ammonium thiosulfate mixture), 10-34-0 (ammonium polyphosphate), or a combination of 28-0-0-5 and 10-34-0, resulting in a 23-9-0. These fertilizers are usually applied at planting as a surface dribble, or as a 2 by 2 band meaning the fertilizer is placed 2 inches to the side and 2 inches below the depth of the seed. These fertilizers provide plants with nitrogen and phosphorus for early season growth. The 28-0-0-5 also contains sulfur via ammonium thiosulfate. Chelates provide crops with micro-nutrients and can be added to starter liquid fertilizers but are only advised when needed based on soil test results.

Yield response to starter fertilizer is variable but is more likely in situations where soil test indicates deficiency of one or more nutrient supplied by the starter fertilizer. There is more likely to be a yield response to starter fertilizer in cool coarse textured sandy soils (containing low organic matter and mineralization rates). That is why starter fertilizer is generally recommended for north Florida field corn production due to our sandy soils and potential cool soil temperatures during planting time from late February through early April. Some of the benefits of using starter fertilizer include improved early-season growth and root development, faster dry down of crops, and potential for increased yield.

Include or exclude Phosphorus in starter fertilizer?

Whether phosphorus should be included in starter fertilizer applications is a common question in the Suwannee Valley area of North Florida. Phosphorus is a macronutrient that plays an important role in plant energy transfer, photosynthesis, and early season root development. Soils in the Suwannee Valley region often test in the high range for phosphorus according to UF/IFAS recommendations using the Mehlich 3 extraction. For irrigated field corn planted at a population of 30,000 plants or above, the current UF/IFAS recommendation is 175 lbs. of P₂O₅ for low (≤ 25 mg kg^-1) P soils, 80 lbs. of P₂O₅ for medium (26 – 45 mg kg^-1) P soils, and 0 lbs. of P₂O₅ for high (>46 mg kg^-1) P soils. However, the UF/IFAS Field corn production guide states that 15 lbs. of phosphorus via starter fertilizer is adequate when soils test in the high range for phosphorus. Research is on-going to review UF/IFAS phosphorus fertilizer rate recommendations across various crops including field corn. For now, note that yield response to the addition of phosphorus in starter fertilizer is variable but is more likely in sandy textured soils and cool/wet conditions. These conditions can cause corn to exhibit phosphorus deficiency symptoms (stunted growth and purple leaves) even when phosphorus tests high based on soil test recommendations. This is due to lower mineralization rates of cool sandy soils and the fungi responsible for helping corn absorb phosphorus being less active at cold temperatures.

In North Florida field corn production, starter fertilizers commonly include liquid blends such as 28-0-0-5 (urea ammonium nitrate and ammonium thiosulfate mixture), 10-34-0 (ammonium polyphosphate), or a combination of 28-0-0-5 and 10-34-0, resulting in a 23-9-0. These fertilizers are usually applied at planting as a surface dribble, or as a 2 by 2 band meaning the fertilizer is placed 2 inches to the side and 2 inches below the depth of the seed. These fertilizers provide plants with nitrogen and phosphorus for early season growth. The 28-0-0-5 also contains sulfur via ammonium thiosulfate. Chelates provide crops with micro-nutrients and can be added to starter liquid fertilizers but are only advised when needed based on soil test results.

Yield response to starter fertilizer is variable but is more likely in situations where soil test indicates deficiency of one or more nutrient supplied by the starter fertilizer. There is more likely to be a yield response to starter fertilizer in cool coarse textured sandy soils (containing low organic matter and mineralization rates). That is why starter fertilizer is generally recommended for north Florida field corn production due to our sandy soils and potential cool soil temperatures during planting time from late February through early April. Some of the benefits of using starter fertilizer include improved early-season growth and root development, faster dry down of crops, and potential for increased yield.

Include or exclude Phosphorus in starter fertilizer?

Whether phosphorus should be included in starter fertilizer applications is a common question in the Suwannee Valley area of North Florida. Phosphorus is a macronutrient that plays an important role in plant energy transfer, photosynthesis, and early season root development. Soils in the Suwannee Valley region often test in the high range for phosphorus according to UF/IFAS recommendations using the Mehlich 3 extraction. For irrigated field corn planted at a population of 30,000 plants or above, the current UF/IFAS recommendation is 175 lbs. of P₂O₅ for low (≤ 25 mg kg^-1) P soils, 80 lbs. of P₂O₅ for medium (26 – 45 mg kg^-1) P soils, and 0 lbs. of P₂O₅ for high (>46 mg kg^-1) P soils. However, the UF/IFAS Field corn production guide states that 15 lbs. of phosphorus via starter fertilizer is adequate when soils test in the high range for phosphorus. Research is on-going to review UF/IFAS phosphorus fertilizer rate recommendations across various crops including field corn. For now, note that yield response to the addition of phosphorus in starter fertilizer is variable but is more likely in sandy textured soils and cool/wet conditions. These conditions can cause corn to exhibit phosphorus deficiency symptoms (stunted growth and purple leaves) even when phosphorus tests high based on soil test recommendations. This is due to lower mineralization rates of cool sandy soils and the fungi responsible for helping corn absorb phosphorus being less active at cold temperatures.

Introduction

Organic amendments come from sources that were once alive and are applied to agricultural soils to increase nutrient and/or organic matter content. Increasing organic matter content of the soil has many benefits including improving water holding capacity, infiltration, and nutrient-holding capacity. Many organic amendments are good sources of plant essential nutrients. Organic amendments can also serve as a food source for soil organisms. Common organic amendments used in Florida agriculture include chicken litter, manure, compost, biosolids, and biochar.

Chicken Litter

Chicken or poultry litter is a common organic amendment used in agricultural production. Chicken litter is defined as chicken manure mixed with bedding material such as straw, rice hulls, and pine shavings. Because it is manure, it is often composted to break down pathogens. The standards that the litter must meet to be used depend on the crop and is regulated by the US Food and Drug Administration.

The pH of chicken litter commonly ranges from neutral to alkaline (6.5 – 8.0). Chicken litter from layer hens tends to contain higher pH compared to broiler hens. Layer hens are fed diets supplemented with calcium to improve eggshell development. Excess calcium present in chicken manure and in broken eggshells can add to the calcium carbonate content of chicken litter, raising pH. Layer hen manure is not always mixed with additional bedding material and can be utilized wet or dry. Broiler chicken litter tends to have a higher nutrient content but varies based on the bedding material used, the diets the chickens are fed, and how frequently chicken litter is emptied out of chicken houses. A local analysis of one source of chicken litter (derived from layer hens) claims a Nitrogen, Phosphorus, and Potassium content of (3%-3%-3%).

Manure

Manure is derived from various livestock animals including swine, cattle (beef and dairy), horses, etc. Manure that has not been composted can contain high nitrogen content compared to composted materials. Given the high nitrogen content, plants can be damaged due to ammonium toxicity when applied in excess or not properly incorporated into soils. Raw manure is generally not applied during the growing season to crops grown for human consumption. Like other organic amendments, manure is variable in terms of nutrient content, salinity, and pH depending on source and feedstock of livestock. Manure can contain viable weed seeds.

Compost

Compost is a term used to describe a variety of decomposed organic materials. Many compost materials are heated by the decomposition process which can destroy pathogens and weed seeds in the compost. The heating process fueled by microbial decomposition, the thermophilic stage of decomposition, is where temperatures of 104 – 140 degrees Fahrenheit can be reached. Fully decomposed compost looks dark, feels crumbly, and smells earthy. A variety of organic sources can be composted including plant-based sources, manure, food wastes, and even whole livestock. Little if any of the original organic material should be recognizable in a fully decomposed compost.

Vermicompost is a type of compost that uses worms in the decomposition process. Many different sources are used in compost mixes. Therefore, compost blends can differ in their nutrient content. It is always best to test compost blends to better understand their nutrient content and pH. Some compost blends, such as those that derive from food waste, could have high salinity levels which could be problematic for crop production.

Biosolids

Bio-solids are an organic amendment derived from human waste and the treatment of domestic sewage. Like other organic amendments, biosolids should be tested for nutrient content given the variability in nutrient content among different sources. Regulation requires biosolids to be treated to reduce pathogen content. They are also analyzed so as not to exceed heavy metal contaminant concentration thresholds. In Florida, biosolids are separated into three classes based on their degree of treatment of pathogens: Class B (the least treated), Class A (intermediate level of treatment), and Class AA (highest level of treatment). The land application of Class B and A biosolids are restricted to permitted sites, while Class AA biosolids are not restricted and are distributed for use as fertilizer in Florida.

Biochar

Biochar is an organic amendment that resembles charcoal and is derived from organic amendments. Biochar is usually created through the process of pyrolysis which involves heating organic material to high temperatures around 500 °C in the absence of oxygen. The absence of oxygen prevents the complete combustion of the organic material used. Biochar is a stable form of carbon that resists degradation, potentially releasing nutrients over a prolonged period compared to organic amendments that have not undergone pyrolysis. Various sources are used to create biochar including, but not limited to, manure, chicken litter, wood chips, and sewage sludge. Given the various sources used to create biochar, nutrient content among biochar’s differ.

Additional Considerations

Apply organic amendments evenly over the soil surface to avoid concentrated deposits. Tillage can assist with the incorporation and distribution of organic amendments across a field. Tillage also speeds up the decomposition process causing nutrients such as nitrogen to become available to plants.

Consider the carbon to nitrogen ratio (C:N ratio) of the organic amendment. Microorganisms present in the soil require both nitrogen and carbon to function. When the C:N ratio is high (high carbon content compared to nitrogen) the organic material decomposes slowly as microorganisms in the soil inefficiently break down the material. In low C:N ratios (low carbon content compared to nitrogen) organic materials break down quickly as microorganisms in the soil uptake nitrogen rapidly. The rate of decomposition will affect when essential nutrients in organic materials become available to plants.

Always consider the moisture content of organic amendments when determining nutrient content. Monitor the pH of the material and the soil at the application site over time. Analyze the nutrient content of the organic amendment and soils to ensure repeated applications do not cause nutrients to build up to excessive levels that negatively impact plant health or the environment. The UF/IFAS Livestock Waste Testing Laboratory provides nutrient analysis for manures. The UF/IFAS Soil Extension Laboratory also provides a container media analysis which may be applicable to organic amendment soil mixes used for potted plants.

Introduction

Organic amendments come from sources that were once alive and are applied to agricultural soils to increase nutrient and/or organic matter content. Increasing organic matter content of the soil has many benefits including improving water holding capacity, infiltration, and nutrient-holding capacity. Many organic amendments are good sources of plant essential nutrients. Organic amendments can also serve as a food source for soil organisms. Common organic amendments used in Florida agriculture include chicken litter, manure, compost, biosolids, and biochar.

Chicken Litter

Chicken or poultry litter is a common organic amendment used in agricultural production. Chicken litter is defined as chicken manure mixed with bedding material such as straw, rice hulls, and pine shavings. Because it is manure, it is often composted to break down pathogens. The standards that the litter must meet to be used depend on the crop and is regulated by the US Food and Drug Administration.

The pH of chicken litter commonly ranges from neutral to alkaline (6.5 – 8.0). Chicken litter from layer hens tends to contain higher pH compared to broiler hens. Layer hens are fed diets supplemented with calcium to improve eggshell development. Excess calcium present in chicken manure and in broken eggshells can add to the calcium carbonate content of chicken litter, raising pH. Layer hen manure is not always mixed with additional bedding material and can be utilized wet or dry. Broiler chicken litter tends to have a higher nutrient content but varies based on the bedding material used, the diets the chickens are fed, and how frequently chicken litter is emptied out of chicken houses. A local analysis of one source of chicken litter (derived from layer hens) claims a Nitrogen, Phosphorus, and Potassium content of (3%-3%-3%).

Manure

Manure is derived from various livestock animals including swine, cattle (beef and dairy), horses, etc. Manure that has not been composted can contain high nitrogen content compared to composted materials. Given the high nitrogen content, plants can be damaged due to ammonium toxicity when applied in excess or not properly incorporated into soils. Raw manure is generally not applied during the growing season to crops grown for human consumption. Like other organic amendments, manure is variable in terms of nutrient content, salinity, and pH depending on source and feedstock of livestock. Manure can contain viable weed seeds.

Compost

Compost is a term used to describe a variety of decomposed organic materials. Many compost materials are heated by the decomposition process which can destroy pathogens and weed seeds in the compost. The heating process fueled by microbial decomposition, the thermophilic stage of decomposition, is where temperatures of 104 – 140 degrees Fahrenheit can be reached. Fully decomposed compost looks dark, feels crumbly, and smells earthy. A variety of organic sources can be composted including plant-based sources, manure, food wastes, and even whole livestock. Little if any of the original organic material should be recognizable in a fully decomposed compost.

Vermicompost is a type of compost that uses worms in the decomposition process. Many different sources are used in compost mixes. Therefore, compost blends can differ in their nutrient content. It is always best to test compost blends to better understand their nutrient content and pH. Some compost blends, such as those that derive from food waste, could have high salinity levels which could be problematic for crop production.

Biosolids

Bio-solids are an organic amendment derived from human waste and the treatment of domestic sewage. Like other organic amendments, biosolids should be tested for nutrient content given the variability in nutrient content among different sources. Regulation requires biosolids to be treated to reduce pathogen content. They are also analyzed so as not to exceed heavy metal contaminant concentration thresholds. In Florida, biosolids are separated into three classes based on their degree of treatment of pathogens: Class B (the least treated), Class A (intermediate level of treatment), and Class AA (highest level of treatment). The land application of Class B and A biosolids are restricted to permitted sites, while Class AA biosolids are not restricted and are distributed for use as fertilizer in Florida.

Biochar

Biochar is an organic amendment that resembles charcoal and is derived from organic amendments. Biochar is usually created through the process of pyrolysis which involves heating organic material to high temperatures around 500 °C in the absence of oxygen. The absence of oxygen prevents the complete combustion of the organic material used. Biochar is a stable form of carbon that resists degradation, potentially releasing nutrients over a prolonged period compared to organic amendments that have not undergone pyrolysis. Various sources are used to create biochar including, but not limited to, manure, chicken litter, wood chips, and sewage sludge. Given the various sources used to create biochar, nutrient content among biochar’s differ.

Additional Considerations

Apply organic amendments evenly over the soil surface to avoid concentrated deposits. Tillage can assist with the incorporation and distribution of organic amendments across a field. Tillage also speeds up the decomposition process causing nutrients such as nitrogen to become available to plants.

Consider the carbon to nitrogen ratio (C:N ratio) of the organic amendment. Microorganisms present in the soil require both nitrogen and carbon to function. When the C:N ratio is high (high carbon content compared to nitrogen) the organic material decomposes slowly as microorganisms in the soil inefficiently break down the material. In low C:N ratios (low carbon content compared to nitrogen) organic materials break down quickly as microorganisms in the soil uptake nitrogen rapidly. The rate of decomposition will affect when essential nutrients in organic materials become available to plants.

Always consider the moisture content of organic amendments when determining nutrient content. Monitor the pH of the material and the soil at the application site over time. Analyze the nutrient content of the organic amendment and soils to ensure repeated applications do not cause nutrients to build up to excessive levels that negatively impact plant health or the environment. The UF/IFAS Livestock Waste Testing Laboratory provides nutrient analysis for manures. The UF/IFAS Soil Extension Laboratory also provides a container media analysis which may be applicable to organic amendment soil mixes used for potted plants.

Agriculture requires major investments before and during the growing season. Farmers need to invest in agricultural inputs (seed, fertilizer, pesticides, etc.) to produce and sell a final product. The more efficiently farmers manage these inputs, the better chance they have at making a profit once it is time to sell their grain, peanuts, livestock, etc.

There are end of the year financial decisions farmers can make to efficiently manage agricultural inputs: One method is pre-paying for agricultural inputs. Agricultural retailers are incentivized to book early orders with their customers to provide certainty they will sell their distributor’s product. Many retailers provide deals at the end of the year to guarantee orders for the new year. When it comes to supply, pre-ordering might ensure you will be able to purchase the input before it sells out. Supply chain issues in recent years have resulted in increased prices and reduced availability of many agricultural inputs. Preordering inputs could lock in lower prices and ensure product availability. However, farmers should check with their retailer about what happens if the price of the agricultural input you are pre-ordering decreases or if the product is unavailable come spring. Some retailers provide price protection. Prepaying does require faith that your retailer will supply you the input at the promised price at a later date.

Another reason farmers prepay for agricultural inputs is to manage their taxes. Farmers might be able to deduct expenses on agricultural inputs purchased before January 1^st even though the inputs are not delivered to the farmer until the following year when needed. Whether a farmer is incentivized to deduct taxes for the current year depends on their income. It is best to discuss these decisions with your tax advisor to determine the best strategy. In situations when the deduction is not needed for the current year agricultural inputs can be purchased or prepaid after January 1^st. Some basic rules to follow if one plans to deduct a prepaid expense:

• Make sure your invoice lists the specific product purchased at exact prices and quantities.
• According to the IRS “your deduction for prepaid farm supplies in the year you pay for them may be limited to 50% of your other deductible farm expenses for the year.”
• The deducted payment covers costs that are reasonably expected to be utilized in the following year.
• Keep accurate, timely, and complete records of all expenses and income related to the farm business!

End of the Year Financial Decisions for Farmers Video

For more information see the video below:

Agriculture requires major investments before and during the growing season. Farmers need to invest in agricultural inputs (seed, fertilizer, pesticides, etc.) to produce and sell a final product. The more efficiently farmers manage these inputs, the better chance they have at making a profit once it is time to sell their grain, peanuts, livestock, etc.

There are end of the year financial decisions farmers can make to efficiently manage agricultural inputs: One method is pre-paying for agricultural inputs. Agricultural retailers are incentivized to book early orders with their customers to provide certainty they will sell their distributor’s product. Many retailers provide deals at the end of the year to guarantee orders for the new year. When it comes to supply, pre-ordering might ensure you will be able to purchase the input before it sells out. Supply chain issues in recent years have resulted in increased prices and reduced availability of many agricultural inputs. Preordering inputs could lock in lower prices and ensure product availability. However, farmers should check with their retailer about what happens if the price of the agricultural input you are pre-ordering decreases or if the product is unavailable come spring. Some retailers provide price protection. Prepaying does require faith that your retailer will supply you the input at the promised price at a later date.

Another reason farmers prepay for agricultural inputs is to manage their taxes. Farmers might be able to deduct expenses on agricultural inputs purchased before January 1^st even though the inputs are not delivered to the farmer until the following year when needed. Whether a farmer is incentivized to deduct taxes for the current year depends on their income. It is best to discuss these decisions with your tax advisor to determine the best strategy. In situations when the deduction is not needed for the current year agricultural inputs can be purchased or prepaid after January 1^st. Some basic rules to follow if one plans to deduct a prepaid expense:

• Make sure your invoice lists the specific product purchased at exact prices and quantities.
• According to the IRS “your deduction for prepaid farm supplies in the year you pay for them may be limited to 50% of your other deductible farm expenses for the year.”
• The deducted payment covers costs that are reasonably expected to be utilized in the following year.
• Keep accurate, timely, and complete records of all expenses and income related to the farm business! 😊

For more information see the video below:

The University of Florida Herbarium recently identified tropical girdlepod (Mitracarpus hirtus) for the first time from Columbia County. This weed has been identified in 23 other Florida counties including many of those in the panhandle and north/central peninsula. The plant is native to the West Indies, South America, Mexico, and Central America. It is introduced (non-native) in much of the world’s tropical and subtropical regions including the U.S. Gulf Coast states and Hawaii.

Tropical girdlepod is a member of the Rubiaceae plant family often referred to as the madder, coffee, or bedstraw family. In Florida, the plant grows as a summer annual–meaning it appears during the warmer months of the year and flowers, set seed, and dies within a single year. Typically growing 1-2 feet tall, tropical girdlepod often has multiple stems branching at or near ground level. These stems are predominantly green, 4-angled, and finely hairy, but basal stems can become woody, rounded, and hairless with age. The leaves are usually 1-2 inches long, oblong to elliptic in shape, and sessile (lacking a petiole or leaf stalk). The tiny white flowers are in clusters at both the branch tips and the leaf axils. Resembling false buttonweeds (genus Spermacoce), tropical girdlepod can be distinguished by examining the tiny capsular fruit under a microscope. In Mitracarpus, the capsules open along a transverse circular line, so that the top separates like a lid. In contrast, Spermacoce capsules open via a longitudinal slit along the inner surface, not separating into two parts. Consult your local extension agent, plant identification expert, or the University of Florida Herbarium for help distinguishing between these two species.

Control methods:

Currently there is no information available on how to control tropical girdlepod using herbicides under Florida conditions in crops, turf, pastures, or landscapes. Research elsewhere indicates the preemergence herbicides atrazine, diuron, oxadiazon or postemergence herbicides such as 2,4-D or glyphosate are effective (Husson et al. 2010). However, poor control was observed following a single application of glyphosate (24 oz of 53% glyphosate per acre rate) at one location in Columbia County.

References

Husson, O., H. Charpentier, F.-X. Chabaud, K. Naudin, Rakotondramanana L.S. (2010). Flore des jachères et adventices des cultures. Annexe 1 : les principales plantes de jachères et adventices des cultures à Madagascar. In : Manuel pratique du semis direct à Madagascar. Annexe 1 – Antananarivo : GSDM/CIRAD, 2010 : 64 p.

The commercial products listed are possible recommendations to help manage tropical girdlepod. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

The University of Florida Herbarium recently identified tropical girdlepod (Mitracarpus hirtus) for the first time from Columbia County. This weed has been identified in 23 other Florida counties including many of those in the panhandle and north/central peninsula. The plant is native to the West Indies, South America, Mexico, and Central America. It is introduced (non-native) in much of the world’s tropical and subtropical regions including the U.S. Gulf Coast states and Hawaii.

Tropical girdlepod is a member of the Rubiaceae plant family often referred to as the madder, coffee, or bedstraw family. In Florida, the plant grows as a summer annual–meaning it appears during the warmer months of the year and flowers, set seed, and dies within a single year. Typically growing 1-2 feet tall, tropical girdlepod often has multiple stems branching at or near ground level. These stems are predominantly green, 4-angled, and finely hairy, but basal stems can become woody, rounded, and hairless with age. The leaves are usually 1-2 inches long, oblong to elliptic in shape, and sessile (lacking a petiole or leaf stalk). The tiny white flowers are in clusters at both the branch tips and the leaf axils. Resembling false buttonweeds (genus Spermacoce), tropical girdlepod can be distinguished by examining the tiny capsular fruit under a microscope. In Mitracarpus, the capsules open along a transverse circular line, so that the top separates like a lid. In contrast, Spermacoce capsules open via a longitudinal slit along the inner surface, not separating into two parts. Consult your local extension agent, plant identification expert, or the University of Florida Herbarium for help distinguishing between these two species.

Control methods:

Currently there is no information available on how to control tropical girdlepod using herbicides under Florida conditions in crops, turf, pastures, or landscapes. Research elsewhere indicates the preemergence herbicides atrazine, diuron, oxadiazon or postemergence herbicides such as 2,4-D or glyphosate are effective (Husson et al. 2010). However, poor control was observed following a single application of glyphosate (24 oz of 53% glyphosate per acre rate) at one location in Columbia County.

References

Husson, O., H. Charpentier, F.-X. Chabaud, K. Naudin, Rakotondramanana L.S. (2010). Flore des jachères et adventices des cultures. Annexe 1 : les principales plantes de jachères et adventices des cultures à Madagascar. In : Manuel pratique du semis direct à Madagascar. Annexe 1 – Antananarivo : GSDM/CIRAD, 2010 : 64 p.

The commercial products listed are possible recommendations to help manage tropical girdlepod. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

Sampling corn tissue is an important practice to conduct during the growing season. Tissue testing can help diagnose nutrient deficiencies, which can limit yield and help to evaluate the efficacy of fertilizer management strategies. Tissue sampling during the season determines what nutrients actually make it into the plant from the soil and added fertilizers. Once identified, deficiencies can be corrected via the application of supplemental nutrients depending on when samples are taken and the application equipment the grower has access to (e.g., high clearance applicator, fertigation via center pivot, airplane).

Recommendations on which plant part to sample for the given growth stage may vary slightly between laboratories. Typically for plants under 12 inches tall, the entire aboveground portion of the plant is cut about 1 inch above the soil. For plants taller than 12 inches but prior to tasseling/reproductive growth the most recently matured leaf below the whorl is sampled. Corn in the post tasseling reproductive growth stages is sampled by collecting the leaf opposite and below the ear. It is important to representatively sample from random locations throughout the field avoiding outlying areas where plant health is not representative of the entire field.

For more information see video below:

Sampling corn tissue is an important practice to conduct during the growing season. Tissue testing can help diagnose nutrient deficiencies, which can limit yield and help to evaluate the efficacy of fertilizer management strategies. Tissue sampling during the season determines what nutrients actually make it into the plant from the soil and added fertilizers. Once identified, deficiencies can be corrected via the application of supplemental nutrients depending on when samples are taken and the application equipment the grower has access to (e.g., high clearance applicator, fertigation via center pivot, airplane).

Recommendations on which plant part to sample for the given growth stage may vary slightly between laboratories. Typically for plants under 12 inches tall, the entire aboveground portion of the plant is cut about 1 inch above the soil. For plants taller than 12 inches but prior to tasseling/reproductive growth the most recently matured leaf below the whorl is sampled. Corn in the post tasseling reproductive growth stages is sampled by collecting the leaf opposite and below the ear. It is important to representatively sample from random locations throughout the field avoiding outlying areas where plant health is not representative of the entire field.

For more information see video below:

Field Corn Tissue Sampling Video

Petiole Sap testing is an educational tool and service provided to vegetable growers in the Suwannee Valley region of North Florida by UF/IFAS Extension. Using portable meters, UF/IFAS Extension agents provide vegetable growers information on the current nitrogen and potassium nutrient status of their crop. This information is beneficial for growers and allows them to identify whether their crop nutrient status is deficient, adequate, or excessive. Adjusting nitrogen and/or potassium rates based on petiole sap test results prevents the limiting of yield from insufficient fertilizer use and unnecessary increases in input costs from excessive application of fertilizer. The information is also helpful from an environmental perspective, helping growers avoid the loss of excess nitrogen to the environment. The most common crop the petiole sap testing is implemented on in the Suwannee Valley region is watermelon.

The petiole sap testing methodology involves sampling petioles of the most recently matured leaf (usually the 5th or 6th leaf from the tip of a watermelon vine) from at least 5-6 representative locations of a field. The petioles are then squeezed in a garlic press to create a sap. The sap is analyzed using calibrated portable meters to determine the nitrate-nitrogen, and potassium content. The results are compared to optimum ranges for the current growth stage of the crop which have been pre-determined based on University of Florida research.

For more information on petiole sap testing see link to UF/IFAS Extension article and video below:

Plant Petiole Sap-Testing for Vegetable Crops: CV004/CIR1144

https://edis.ifas.ufl.edu/cv004

Watermelon Petiole Sap Testing Video: 

Introduction

The maize weevil (Sitophilus zeamais) is a major pest of corn, particularly in subtropical and tropical regions. In the southeastern United States, it is among the most damaging pests corn growers face, costing the agricultural industry millions of dollars annually. Both adults and larvae can infest corn, whether it is standing corn or stored post-harvest. Maize weevils are most commonly spotted as adults and look like small brown beetles with distinctive snouts. Adult females will chew holes into kernels, laying a single egg inside. From the egg, a larva will emerge. By feeding from within the kernel, the larva will complete its development, pupate, and eventually emerge as an adult beetle.

Management

Maize weevil’s can be managed through multiple strategies:

• Timely Harvest and Sanitation: Timely harvest and sanitation are the best practices for preventing maize weevil infestations in the field. Harvesting on time means maize weevils have less time to infest and reproduce on standing corn crops. Often, maize weevils will infest the edges of fields before moving on to the rest of the crop. When maize weevils are present on edges of the field these areas can be harvested first and stored separately. Growers should clean spilled grain and discard old grain before adding new grain into storage.
• Temperature and Moisture Control: Temperature and moisture control are effective strategies for managing maize weevils in stored corn. Maize weevils are unable to move or develop at temperatures cooler than 50 degrees Fahrenheit. The temperature of stored grain bins can be managed using aeration. However, it is difficult to maintain this temperature in the late summer and early fall months in North Florida. Storing grain at less than 11% moisture is also helpful for controlling maize weevils.
• Chemical Control: Insecticides can be applied as protectants or fumigants when grain is being placed into storage. Protectant insecticides are applied with the intent of providing long-lasting control for many months of storage. Fumigants are gasses that are short-lived, but fast-acting, and can be applied reactively to infestation. Application of fumigants is often labor-intensive and costly. Fumigant applicators should carefully follow label directions as inhalation of fumigant gasses can result in severe injury or death. Field applications of insecticide are not recommended. See table 1 and 2 for list of various fumigant and protectant insecticides for controlling maize weevils during the storage process.
• Resistance: Different varieties of corn have different levels of susceptibility to maize weevils. Identifying whether a variety is resistant or susceptible can help growers anticipate what chemical control inputs may be needed.

Table 1: Fumigant products labeled for maize weevil control (Table 1).

Table 2: Protectant insecticide products labeled for maize weevil control (Table 2).

The commercial products listed are possible recommendations to help manage maize weevil pests in field corn production. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

Introduction

The maize weevil (Sitophilus zeamais) is a major pest of corn, particularly in subtropical and tropical regions. In the southeastern United States, it is among the most damaging pests corn growers face, costing the agricultural industry millions of dollars annually. Both adults and larvae can infest corn, whether it is standing corn or stored post-harvest. Maize weevils are most commonly spotted as adults and look like small brown beetles with distinctive snouts. Adult females will chew holes into kernels, laying a single egg inside. From the egg, a larva will emerge. By feeding from within the kernel, the larva will complete its development, pupate, and eventually emerge as an adult beetle.

Management

Maize weevil’s can be managed through multiple strategies:

• Timely Harvest and Sanitation: Timely harvest and sanitation are the best practices for preventing maize weevil infestations in the field. Harvesting on time means maize weevils have less time to infest and reproduce on standing corn crops. Often, maize weevils will infest the edges of fields before moving on to the rest of the crop. When maize weevils are present on edges of the field these areas can be harvested first and stored separately. Growers should clean spilled grain and discard old grain before adding new grain into storage.
• Temperature and Moisture Control: Temperature and moisture control are effective strategies for managing maize weevils in stored corn. Maize weevils are unable to move or develop at temperatures cooler than 50 degrees Fahrenheit. The temperature of stored grain bins can be managed using aeration. However, it is difficult to maintain this temperature in the late summer and early fall months in North Florida. Storing grain at less than 11% moisture is also helpful for controlling maize weevils.
• Chemical Control: Insecticides can be applied as protectants or fumigants when grain is being placed into storage. Protectant insecticides are applied with the intent of providing long-lasting control for many months of storage. Fumigants are gasses that are short-lived, but fast-acting, and can be applied reactively to infestation. Application of fumigants is often labor-intensive and costly. Fumigant applicators should carefully follow label directions as inhalation of fumigant gasses can result in severe injury or death. Field applications of insecticide are not recommended. See table 1 and 2 for list of various fumigant and protectant insecticides for controlling maize weevils during the storage process.
• Resistance: Different varieties of corn have different levels of susceptibility to maize weevils. Identifying whether a variety is resistant or susceptible can help growers anticipate what chemical control inputs may be needed.

Table 1: Fumigant products labeled for maize weevil control (Table 1).

Table 2: Protectant insecticide products labeled for maize weevil control (Table 2).

The commercial products listed are possible recommendations to help manage maize weevil pests in field corn production. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

Introduction

Sulfur is one of the earliest known pesticides. The ancient Greeks found the application of sulfur to prevent wheat smut and rust diseases in wheat. Lime sulfur and sulfur dioxide were also used as insecticides. Sulfur is one of the earliest fungicides to be used in peanut production for the control of foliar diseases such as early and late leaf spot.

Today, sulfur is still used as a preventative fungicide, meaning it must be applied prior to fungal disease development. Sulfur is sold in various pesticide formulations including dust, liquid, dry flowable, and wettable powder. Oil based sprays and sulfur should not be mixed or applied within short succession of one another as the combination can be phytotoxic.

The use of sulfur in peanut production declined in the early 1970s with the introduction of new fungicides such as benomyl and chlorothalonil. Recently, growers have begun adding micronized sulfur into their spray program. Researchers have found micronized sulfur to improve leaf spot control compared to control treatments when applied alone on a bi-weekly basis. However, it has not been found to perform as well as traditional fungicides when there is no resistance. Micronized sulfur is generally mixed with fungicides of the 3, 7, and 11 FRAC groups with the goal of improving leaf spot control and slowing the development of resistance against current fungicide products. Micronized sulfur provides growers with an economical option for leaf spot control. Generally, micronized sulfur is applied in 2 or 3 separate applications early to mid-season. An application rate of about 5 lbs. per acre is recommended. Agitation is required to keep micronized sulfur in solution in the spray tank.

Micronized Sulfur On-Farm Trial Results from Hamilton and Columbia County

During the 2021 peanut season, on-farm trials were conducted in Hamilton and Columbia County. An application rate of 3 lbs. of micronized sulfur per acre was added as a tank mix to 2 applications of the fungicide spray program. Yield results were recorded from the Hamilton County trial. Only leaf spot ratings were recorded from the Columbia County trial. Treatments containing micronized sulfur tended to have lower defoliation results than the other treatments in both trials. However, this reduction did not lead to a significant yield increase in the Hamilton County trial as seen by comparing treatments 3 and 4. In fact, all treatment yields were not significantly different from each other in the Hamilton County trial despite treatment 1, Provost® Silver added to sprays 4 and 6, having a numerically higher yield. Disease onset also occurred late in the Hamilton County trial beginning around the end of July. It is important to note that all the micronized sulfur applications were completed on July 20^th, before disease onset.

Figure 1: Fungicide spray programs by treatment for the Hamilton County trial. Planted on 5/10/2021. Peanut variety used was TifNV-HiOL. DAP = Days after planting.

Table 1: Percent defoliation and leaf spot ratings¹ recorded on September 16^th. Foliar disease onset in this trial occurred in late July to early August.

Table 2: Leaf spot ratings¹ were collected twice towards the end of the season on August 13^th and September 13^th from the Columbia County on-farm trial. Planted on 04/26/2021. Peanut variety used was Florida-07. Two spray program treatments were compared which differed only by micronized sulfur being mixed into the 3rd and 4th fungicide spray. Leaf spot ratings were recorded from 4 representative locations in each treatment area.

¹ The guidelines below were followed when recording leaf spot ratings from the Florida 1 to 10 intensity scale for leaf spots and rust: 1 = No disease, 2 = Very few lesions (none on the upper canopy), 3= Few lesions (very few on upper canopy), 4 = Some lesions with more on upper canopy than rank of 3 and slight defoliation noticeable, 5 = Lesions noticeable on upper canopy with noticeable defoliation, 6 = Lesions numerous and very evident on upper canopy with significant defoliation (50%+), 7 = Lesions numerous on upper canopy with much defoliation (75%+), 8 = Upper canopy covered with lesions with high defoliation (90%+), 9 = Very few leaves remaining and those covered with lesions (some plants completely defoliated), 10 = Plants are dead.

The commercial products listed are possible recommendations to help manage plant diseases in peanut production. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

Introduction

Sulfur is one of the earliest known pesticides. The ancient Greeks found the application of sulfur to prevent wheat smut and rust diseases in wheat. Lime sulfur and sulfur dioxide were also used as insecticides. Sulfur is one of the earliest fungicides to be used in peanut production for the control of foliar diseases such as early and late leaf spot.

Today, sulfur is still used as a preventative fungicide, meaning it must be applied prior to fungal disease development. Sulfur is sold in various pesticide formulations including dust, liquid, dry flowable, and wettable powder. Oil based sprays and sulfur should not be mixed or applied within short succession of one another as the combination can be phytotoxic.

The use of sulfur in peanut production declined in the early 1970s with the introduction of new fungicides such as benomyl and chlorothalonil. Recently, growers have begun adding micronized sulfur into their spray program. Researchers have found micronized sulfur to improve leaf spot control compared to control treatments when applied alone on a bi-weekly basis. However, it has not been found to perform as well as traditional fungicides when there is no resistance. Micronized sulfur is generally mixed with fungicides of the 3, 7, and 11 FRAC groups with the goal of improving leaf spot control and slowing the development of resistance against current fungicide products. Micronized sulfur provides growers with an economical option for leaf spot control. Generally, micronized sulfur is applied in 2 or 3 separate applications early to mid-season. An application rate of about 5 lbs. per acre is recommended. Agitation is required to keep micronized sulfur in solution in the spray tank.

Micronized Sulfur On-Farm Trial Results from Hamilton and Columbia County

During the 2021 peanut season, on-farm trials were conducted in Hamilton and Columbia County. An application rate of 3 lbs. of micronized sulfur per acre was added as a tank mix to 2 applications of the fungicide spray program. Yield results were recorded from the Hamilton County trial. Only leaf spot ratings were recorded from the Columbia County trial. Treatments containing micronized sulfur tended to have lower defoliation results than the other treatments in both trials. However, this reduction did not lead to a significant yield increase in the Hamilton County trial as seen by comparing treatments 3 and 4. In fact, all treatment yields were not significantly different from each other in the Hamilton County trial despite treatment 1, Provost® Silver added to sprays 4 and 6, having a numerically higher yield. Disease onset also occurred late in the Hamilton County trial beginning around the end of July. It is important to note that all the micronized sulfur applications were completed on July 20^th, before disease onset.

Figure 1: Fungicide spray programs by treatment for the Hamilton County trial. Planted on 5/10/2021. Peanut variety used was TifNV-HiOL. DAP = Days after planting.

Table 1: Percent defoliation and leaf spot ratings¹ recorded on September 16^th. Foliar disease onset in this trial occurred in late July to early August.

Table 2: Leaf spot ratings¹ were collected twice towards the end of the season on August 13^th and September 13^th from the Columbia County on-farm trial. Planted on 04/26/2021. Peanut variety used was Florida-07. Two spray program treatments were compared which differed only by micronized sulfur being mixed into the 3rd and 4th fungicide spray. Leaf spot ratings were recorded from 4 representative locations in each treatment area.

¹ The guidelines below were followed when recording leaf spot ratings from the Florida 1 to 10 intensity scale for leaf spots and rust: 1 = No disease, 2 = Very few lesions (none on the upper canopy), 3= Few lesions (very few on upper canopy), 4 = Some lesions with more on upper canopy than rank of 3 and slight defoliation noticeable, 5 = Lesions noticeable on upper canopy with noticeable defoliation, 6 = Lesions numerous and very evident on upper canopy with significant defoliation (50%+), 7 = Lesions numerous on upper canopy with much defoliation (75%+), 8 = Upper canopy covered with lesions with high defoliation (90%+), 9 = Very few leaves remaining and those covered with lesions (some plants completely defoliated), 10 = Plants are dead.

The commercial products listed are possible recommendations to help manage plant diseases in peanut production. This blog post is intended for educational purposes. It is not the intention of the authors to provide a complete list of product recommendations or endorse a particular product or brand.

It is mid-July so if foliage feeding caterpillars have not shown up in your peanut field yet, they likely will soon! Two types of caterpillars commonly found in Columbia County July-September are the velvetbean caterpillar and soybean looper. It is important to properly identify the caterpillars in your field to determine management decisions. Velvetbean caterpillars are usually cheaper to manage and can be controlled with many different insecticides (Belt, Besiege Blackhawk, Coragen, Diamond, Dimilin, Intrepid, and Radiant. Along with pyrethroids: Asana, Besiege, Baythroid, Brigade, Mustang Max, Proaxis, etc). There are fewer options available to control soybean loopers (Belt, Besiege, Blackhawk, Coragen, Diamond, Intrepid, Prevathon, Radiant, and Steward). Note that pyrethroids are not recommended for soybean looper control and have the potential to flare spider mites especially in non-irrigated peanuts.

Identification

Unfortunately, velvetbean caterpillars and soybean loopers look similar. However, counting the number of legs or “abdominal prolegs” in the caterpillar’s midsection can be used for identification purposes. The velvetbean caterpillar has 4 pairs of abdominal prolegs while the soybean looper has 2 pairs of abdominal prolegs. Make sure you are only counting the pairs of abdominal prolegs (or the pairs of legs in the caterpillar’s mid-section) and not the anal prolegs at the end of the caterpillar!

Economic Threshold

The economic threshold, or the number of caterpillars per foot, that justifies an insecticide application is 4-8 caterpillars per foot of row. Make sure to check multiple locations throughout the field (approximately 10 representative locations) when determining the economic threshold. Often, hot spots can be found that exceed the economic threshold when most of the field has caterpillar populations below threshold.

Refer to South Carolina Pest Management Handbook for Field Crops for additional information on insecticide options for peanut pests:

https://www.clemson.edu/extension/agronomy/pestmanagement17/insect%20control%20peanuts.pdf

The commercial products listed are possible recommendations to help manage foliage feeding caterpillars in peanut production. This blog post is intended for educational purposes. It is not the intention of the author to provide a complete list of product recommendations or endorse a particular product or brand.

It is mid-July so if foliage feeding caterpillars have not shown up in your peanut field yet, they likely will soon! Two types of caterpillars commonly found in Columbia County July-September are the velvetbean caterpillar and soybean looper. It is important to properly identify the caterpillars in your field to determine management decisions. Velvetbean caterpillars are usually cheaper to manage and can be controlled with many different insecticides (Belt, Besiege Blackhawk, Coragen, Diamond, Dimilin, Intrepid, and Radiant. Along with pyrethroids: Asana, Besiege, Baythroid, Brigade, Mustang Max, Proaxis, etc). There are fewer options available to control soybean loopers (Belt, Besiege, Blackhawk, Coragen, Diamond, Intrepid, Prevathon, Radiant, and Steward). Note that pyrethroids are not recommended for soybean looper control and have the potential to flare spider mites especially in non-irrigated peanuts.

Identification

Unfortunately, velvetbean caterpillars and soybean loopers look similar. However, counting the number of legs or “abdominal prolegs” in the caterpillar’s midsection can be used for identification purposes. The velvetbean caterpillar has 4 pairs of abdominal prolegs while the soybean looper has 2 pairs of abdominal prolegs. Make sure you are only counting the pairs of abdominal prolegs (or the pairs of legs in the caterpillar’s mid-section) and not the anal prolegs at the end of the caterpillar!

Economic Threshold

The economic threshold, or the number of caterpillars per foot, that justifies an insecticide application is 4-8 caterpillars per foot of row. Make sure to check multiple locations throughout the field (approximately 10 representative locations) when determining the economic threshold. Often, hot spots can be found that exceed the economic threshold when most of the field has caterpillar populations below threshold.

Refer to South Carolina Pest Management Handbook for Field Crops for additional information on insecticide options for peanut pests:

https://www.clemson.edu/extension/agronomy/pestmanagement17/insect%20control%20peanuts.pdf

The commercial products listed are possible recommendations to help manage foliage feeding caterpillars in peanut production. This blog post is intended for educational purposes. It is not the intention of the author to provide a complete list of product recommendations or endorse a particular product or brand.