Turf fungal diseases can be very difficult to manage, especially if they recur every year.
In the fall – large patch/brown patch – and in the summer – take-all root rot – are both diseases that can be made worse by too much water and high nitrogen fertilizers. Use of fungicides will not cure the leaves with the symptoms but they can help protect new growth. See the links below for more information about the diseases. Not all fungicides work effectively on these diseases – you should choose a fungicide(s) listed in the publication – AND practice appropriate cultural controls.
Take-all root rot: https://edis.ifas.ufl.edu/pdf/LH/LH07900.pdf
Large patch: https://edis.ifas.ufl.edu/pdf/LH/LH04400.pdf
Practices that may promote healthy turf
- When you buy fertilizer, look for a fertilizer that has a 1:1 or 2:1 ratio of nitrogen (N- 1st number on the bag) and potassium (K- last number on the bag). High nitrogen fertilizers have been linked with pest problems and turf diseases such as take all root rot. The nitrogen and potassium should also be in slow-release form as much as possible.
- Don’t fertilize in winter when grass is dormant. Fertilizing in winter can cause problems the following year.
- Also check the irrigation system to make sure it only delivers ½” – ¾” water per irrigation event and that watering is reduced in winter or when it rains.
- Use UF/IFAS publications for information about care and maintenance of turfgrass: https://edis.ifas.ufl.edu/entity/topic/turfgrasses
- Mow at the right height for your turfgrass. Mowing is one of the easiest and best practices for encouraging healthy grass.
- For a monthly calendar, see the Central Florida Gardening Calendar: https://edis.ifas.ufl.edu/pdf%5CSS%5CSS18700.pdf
- To limit grass injury from herbicides, don’t use a weed-n-feed product on the entire lawn unless there is uniform weed coverage. Treat weeds and fertilize separately. Some herbicides can damage St. Augustinegrass so be sure to follow label instructions.
Soil testing for phosphorous
- You can submit a soil sample to the UF Extension Soil Testing Lab using this form: https://edis.ifas.ufl.edu/pdf%5CSS%5CSS18700.pdf
- The form has instructions for how to take a soil sample in the lawn.
- Choose Test B, $10, for a complete soil analysis.
- If your report comes back that phosphorous (P) is sufficient, you can buy fertilizer with zero P. This can also help reduce P runoff and protect water bodies.
Rapid Turfgrass Diagnostics
- For quick ID of potential turf diseases, use the UF/IFAS Rapid Turfgrass Diagnostic service: https://turf.ifas.ufl.edu/rapiddiag.shtml
- This service costs $75 but you get preliminary results in about 1 – 3 business days. For some, $75 is a value compared with sod replacement costs.
- Do an inexpensive soap flush to check for pests prior to treating for pests. See this less than 2 minute YouTube video for how to do soap flush in your lawn: https://www.youtube.com/watch?v=sx_o4EMXsCo
- An inexpensive dish soap that’s not a degreaser works best. If you need help identifying insects, please contact the Extension office.
- You can use the soap flush technique any time you suspect insects. Chinch bugs, caterpillars and mole crickets can be seen with the naked eye. If you don’t find insects – the cause may be fungal/disease.
- Here’s a UF/IFAS publication with more information on chinch bugs: https://edis.ifas.ufl.edu/pdf/LH/LH03600.pdf
- One of the best ways to prevent disease is to calibrate your irrigation system and use a rain gauge to measure rainfall so you don’t overwater.
- Pests love lots of water and fertilizer and grass that has thatch! Minimize thatch and grass that attracts pests by watering only ½” – ¾” per irrigation event. Check this website for instructions on how to calibrate your irrigation system https://gardeningsolutions.ifas.ufl.edu/care/irrigation/calibrating-your-irrigation-system.html.After you calibrate your irrigation system, you’ll know if you need to water more, less or keep it the same. Any more water than this can contribute to disease.
- If we get plenty of rainfall, cut back the irrigation that week. If we get several inches of rain, adjust your sprinkler system that week or turn it off. Too much water, from either rain or irrigation, can contribute to fungus and disease. An inexpensive rain gauge or weather app can help with checking rainfall in inches.