As temperatures begin to cool down across Northeast Florida, it’s time to start thinking about winter weed control in your hay fields and forage areas.
Winter Weed Introduction
There are many types of winter weeds (annuals, biennials, and perennials) which can cause problems with forage and hay quality. Annual winter weeds typically germinate from the seed during the fall and grow during the winter months. Biennials are plants that take two years to complete their growth cycle. These plants do not produce seeds during their first year, but they do exhibit vegetative growth during the winter months. While perennial weeds are rare, there are a few that are of concern. These weeds are harder to eliminate as they typically have a large underground root system. Examples of winter annuals include fireweed, chickweed, and wild radish. Thistles are one of the most common biennial weeds seen in Northeast Florida, while red sorrel is a permanent plant that has a long, underground root.
The best time to control winter or cool season weeds is when they are small and growing actively. Larger weeds tend to require more herbicide. Large plants are also more difficult to eliminate because they are not in an active growth phase. There are many types of herbicide options for winter weed control. Choosing the right one for the types of weeds that you have and your production schedule will help save you money and potentially increase yield. The following herbicides are commonly used in Northeast Florida. There is additional, specific information below on weeds that we commonly see in this area.
This herbicide can be used in areas where bermudagrass has gone completely dormant during the winter. It provides control of winter grasses (except ryegrass) and broadleaf weeds. Make sure that the bermudagrass is dormant before use. If there is any green tissue, do not use. This will cause damage to the bermudagrass. You should also note that gluphosate can struggle with come common broadleaf weeds such as henbit, primrose, and geranium.
This herbicide is one of the least expensive and most commonly used herbicides for broadleaf weed control. It is effective on wild radish and small thistles. However, it may need to be used in larger quantities if the radish is blooming or if thistle rosettes are more that one (1) foot in diameter.
This herbicide was formerly sold under the trade name Cimarron. It is now available under other trade names as well. Metsulfuron is inexpensive and provides control of many broadleaf weeds, including wild radish, red sorrel, and chickweed. There are currently no haying or grazing restrictions when using metsulfuron. It should be noted that metsulfuron should only be used on bermudagrass pastures. DO NOT USE on BAHIA.
Common Cool Season Weeds
Florida betony is also commonly referred to as rattlesnake weed. It is recognized by a white or tan tuber root that resembles a fat grub. Plant stems are square, with white, pink, or blue flowers. This plant can be difficult to control because of the tuber root. GrazonNext HL at 1.5 pints per acre or Weedmaster at 2 pints per acre will achieve acceptable control.
Cudweed is also known as rabbit tobacco. The plants grow from a basal rosette. Two particular types are commonly found in Northeast Florida; purple cudweed and shiny cudweed. The purple variety exhibits hairy, dull gray leaves, while the shiny variety exhibits bright green leaves with white hair on the underside of the leaf. Control of this plant needs to be achieved before the plant produces seed. Remedy at 1 to 2 pints per acre or GrazonNext HL at 1.5 pints per acre will provide acceptable control.
Thistle is one of the hardest weeds to control because it is a biennial weed, meaning that it takes two years to complete the growth cycle. There are many varieties in Florida, but control measures for all thistle are the same. Since it is a biennial weed, it is observed to grow in a rosette stage during the first year, with bolting and flowering occurring during the second year. Control is best achieved during the rosette stage with 2,4-D. However, if bolting has begun, GrazonNext HL is the only option.
Red sorrel also goes by the name sourweed. The plant has long, underground roots. The leaves are arrowhead-shaped and basal in nature. Stems are typically red. A measure of control can be achieved by adjustment of soil pH and fertility. For those with bermudagrass pastures, metsulfuron at 0.25 ounces per acre will achieve control.
The chickweed plant grows level to the ground with leaves that are opposing and light green in color. Flowers of this plant are small and white and exhibit five (5) deeply lobed petals. Control of chickweed can be achieved by the use of Weedmaster at 2 pints per acre or GrazonNext HL at 1.5 pints per acre.
The leaves of the wild radish plant grow at the lower base of the plant and are covered with thick hairs. As weather warms, the leaves lengthen and a flower stem forms at the top. Flowers are usually yellow. For plants that are less than six (6) inches tall, the use of 2,4-D will provide control. Effectiveness of 2,4-D will decrease as plant height increases over six (6) inches. Larger plants in bermudagrass fields can be controlled with metsulfuron at 0.25 ounces per acre.
The fireweed plant has square stems with leaves that resemble those of strawberry plants. Stinging hairs are located on the stems and the leaves of the plant. Control of this weed is achieved by the use of GrazonNext HL at 1.5 pints per acre. Mowing is not an effective control measure for this plant.
The Cutleaf Geranium plant has hairy stems that are red to pink in color. The leaves of the plant are divided into deep segments and attached to long stalks. Control of Cutleaf Geranium can be achieved with various herbicides. Commonly, 2,4-D at two (2) to four (4) pints per acre will achieve control. Weedmaster at 1.5 to 2 pints per acre and GrazonNext HL at 1.5 pints per acre will also achieve control. For bermudagrass pastures, metsulfuron at 0.25 ounces per acre is effective.