Preventing Summer Lawn Fungus

By, Ann Meisoll

Are strange spots and patches showing up in your lawn? If so, you might have a fungus in your grass. There are several different diseases that can attack your grass, but we’ll only touch on three of them in this article.

Dollar spot appears in the spring and can keep going through the early fall. The fungus appears as a cottony web, easily visible early in the morning when dew is on the grass. Dollar spot is often an indication of low nitrogen, so increasing nitrogen levels can help decrease the incidence of it. Be careful doing this on cool-season turf because it can encourage other diseases, particularly brown patch. Dollar spot is considered a nuisance disease—something to watch, but rarely to treat.

Brown patch is one of the most serious issues for a lawn. Brown patch usually appears as a circular area that looks like a halo or a smoke ring. This disease is prevalent during the hot, wet weather of summer. Cool-season turf that receives a spring feeding heavy in nitrogen is particularly susceptible. Brown patch can kill your lawn, so we recommend treating it as soon as you suspect you might have it.

Fusarium blight tends to occur more where soils are compacted, like in high traffic areas. It displays a patch similar to brown patch, but typically has a green spot near the center of the patch, called a frog-eye.

Solutions:

Dollar spot, brown patch and fusarium blight can all be prevented and/or cured with products containing myclobutanil (Ferti-lome F-Stop). Propiconazole will treat (but not prevent) all three diseases. Ferti-lome Liquid Systemic Fungicide contains this chemical.

Hints to keep your lawn healthy:

• Deep roots are better. Turf with deeper roots holds up against Richmond summers so much better than shallow rooted turf. It becomes more drought and disease resistant, and just looks healthier. We recommend at least 1” of water on your lawn per week, all at once—not spread out over a period of days. Turning the sprinklers on for 20 minutes a day, 3 days a week just isn’t enough.
• When you feed, choose a low nitrogen fertilizer, if at all possible. High nitrogen content will give you lots and lots of green grass, but could also contribute to disease issues. You’ll also have to mow a lot!
• Keep your turf maintained. Keep your mower height set at 3” or more. Make sure the mower blade is sharp. One secret to a healthy lawn is a thin layer of thatch, but too much thatch can cause problems. Either use a dethatching product every few years, or have it dethatched mechanically.
• Sunlight and air circulation are two must-haves for a healthy lawn. Grass needs sun to grow and thrive. Air circulation helps keep the lawn dry and possibly a little cooler, cutting down on the summer stress.