Yellow Grass: Fungi

Spring and fall are the most common times for fungal lawn diseases. Irrigating your grass late in the day makes your grass particularly susceptible to fungal disease. Fungicide applications are most critical/beneficial during damper weather in the spring, early summer, and fall when temperatures are between 70º and 80ºF.

Brown Patch is the most common fungus across all the varieties we carry; however, Texas A&M has a full list of lawn fungi common in Texas with pictures and recommendations on treatment.

Causes/Prevention:

• Ensure proper drainage
• Morning irrigation ONLY
• Irrigate as needed only (once established)
• Avoid frequent, shallow waterings
• Fertilize & water appropriately
• Test soil at least once every 2 years
• Remove excess thatch, leaves, and debris.
• Mow regularly
• Avoid over-fertilizing.
• Aerate yearly
• Topdress twice yearly
• Avoid high-nitrogen fertilizers during drought & excessive heat.
• Clean mowing equipment with a bleach solution after each use

Resolution:

• Confirm the issue is fungal related by hiring a lawn professional or using Texas A&M’s Earth Wise Guide to Lawn Problems Flowchart
• Cut back on irrigation, watering only as needed
• Let lawn dry out completely between waterings
• Identify fungus by hiring a lawn professional or using Texas A&M’s Disease Handbook
• Treat with an appropriate fungicide (p 84)
• Always rotate fungicides from different FRAC groups

If you believe your lawn is infected with a fungus, you need to cut back on your irrigation, letting the area dry out. It is essential that you only water in the morning. Watering during the evening or overnight causes excess moisture to remain on the lawn, promoting an ideal environment for fungal growth. Additionally, you need to treat the yard with a broad-spectrum fungicide, such as Scotts Disease EX.

Be advised that once disease symptoms are present, more than one application will likely be needed. Additionally, Brown Patch lawn disease tends to reappear season after season. It is recommended that preventative fungicides be applied during the spring and fall to areas that have a history of Brown Patch. As with any chemical product, make sure that you read and follow the manufacturer’s instructions, located on the product’s label.

You can control most lawn fungi in our area by applying a fungicide with the same active ingredient, such as azoxystrobin and propiconazole. That said, do NOT use a fungicide containing the same active ingredient more than twice in a row! It is imperative to rotate fungicides from different FRAC groups to prevent resistance.