Lawn Disease Alert: Brown Patch
June 20, 2019
Heavy rains not only compact soils and raise humidity, but also create the perfect environment for fungal diseases, such as brown patch, in your lawn.
Brown patch is caused by the fungus, Rhizoctonia solani. Brown patch typically pops up in spring and fall, when temperatures are moderate, humidity is high, and during periods of excess rainfall (or too much irrigation). If we get excess rain and humidity in summer, you can continue to have issues with brown patch. Too much high-nitrogen fertilizer also contributes to brown patch outbreaks.
Brown patch attacks cool season grasses like rye and fescue in the north. Here in the south, St. Augustine and zoysia grass typically fall victim. Bermudagrass is not as susceptible to the fungus, and is rarely affected.
Signs and Symptoms of Brown Patch
- 6”-2’ diameter circular spots or “patches” that are yellowing
- Lawn patches that turn from yellow to brown or tan over time
- tan lesions on grass leaf blades that have a dark brown border
- in extremely wet conditions, grey, cotton-like growth is seen on grass blades
Even though brown patch is unsightly, it rarely kills an entire lawn – just causing visual damage that may take months to recover. However, if your lawn is suffering from compacted soils, over-saturated soils, nutritional deficiencies, or pest issues, adding brown patch to the mix can be a recipe for lawn death.
The yellowing caused by the disease is commonly confused with Take-all root rot, gray leaf spot, and even grubs or chinch bugs.
How to Control Brown Patch
Even though you can’t control the weather, you can control other factors that lead to brown patch. Follow the tips below to ward off the fungus or control the spread.
- Avoid applying high-nitrogen synthetic fertilizers. Instead, think about incorporating bio-fertilizers that feed the soil & produce healthy plants.
- Don’t overwater – especially when it’s already raining weekly.
- When irrigating, do not water in the evening or night when lawns will stay damp. Instead, water in the morning to allow foliage to dry more quickly.
- If brown patch is present, make sure to bag clippings in order to reduce the spread. Or, make sure your lawn crew is cleaning their mowers between properties.
- Avoid excess thatch buildup. Good air circulation deters the fungus from taking hold.
- Work on improving drainage by aeration.
If you are concerned that you might have a brown patch in your lawn, contact our lawn health care team for help.