Disease Control in Lawns

Is There a Fungus Among Us?

If your lawn is developing areas that yellow and then turn brown, and you cannot find any evidence of insect pests, then you may consider the possibility of a fungus disease, particularly if you have been receiving very frequent rains. Closely examine the grass blades to see if they appear to be rotting off where they are attached to the stem. If so, then a fungus disease is a good possibility. Below are descriptions and images of the most common lawn funguses and the remedies we use to treat them.

Always read and follow the instructions for safe mixing and application on the label of each fungicide you use. Pay close attention to the types of lawns a fungicide can and can't be used on.

Brown Patch

Circular patches of dead grass a few inches to a few feet in diameter appear in the lawn during periods of high humidity and warm temperatures. Brown areas are sometimes surrounded by dark purplish smoky rings. Filmy white tufts cover blades in the early morning before the dew dries. After 2 to 3 weeks, the center may recover and turn green, giving the brown areas a doughnut shape. When the infection becomes severe and warm weather continues, the disease attacks plant crowns and kills the grass. Keep the turf as dry as possible. Watering in the late evening or at night can promote the onset of brown patch. Water only in the morning, 1 or 2 times a week if necessary. Brown patch can be tracked throughout the lawn so try to stay off the grass until the problem is under control.

SOLUTION: Control brown patch with Fertilome Liquid Systemic Fungicide or Bayer Advanced Lawn Fungicide Control Granules. Apply when the disease is first noticed and at least 3 more times at 7 to 10 day intervals.

Slime Mold

Slime mold will not harm your grass or ornamental plants. Slime mold can take on several different appearances depending on where it is growing and how long it has been around.

Slime molds are easy to recognize. They can be seen in turf where the grass blades are covered with a dusty gray layer. This layer may take on a crusty appearance after a few days. Generally no control measures are needed. However, in unusual cases, the layer of crusty growth may become heavy enough to shade grass blades and cause yellowing. If this should occur, or the appearance is simply objectionable, sweeping with a broom easily breaks up slime mold growth.

Rust

Grass turns light green or orange-yellow and begins to thin out. An orange powder that looks like rust coats the grass blades and rubs off on fingers, shoes, and clothing. Reddish brown lesions under the powder do not rub off. Rust develops slowly, often more slowly than the grass grows and is the least common disease mentioned here.

SOLUTION: Apply a high nitrogen fertilizer such as Pennington 27-4-6 Lawn Food to maintain rapid growth. Mow frequently bagging or removing the clippings. If the disease is sever treat with Fertilome Liquid Fungicide, Advanced Lawn Fungicide Granules.. Repeat the application every 7 to 10 days until the lawn improves. Read labels for proper mixing and application instructions.

Disease Prevention Tips

Conditions favoring most lawn diseases are when the weather is warm and humid, and there is an over-abundance of rain.
If you have a sprinkler system make sure not to add to this problem by running it during these wet periods. During dry spells run your sprinkler system during the early morning hours. Watering during the late evening or night time can promote the onset of damaging funguses..
Maintain turfgrass vigor by following proper fertilization requirements for your turf species. SEE: Lawn Care - Fertilization & Maintenance
Mow regularly and remove the clippings every other mowing to reduce thatch buildup and the number of spores, especially if the lawn is infected. Make sure to remove any wet clumps of cut grass after mowing.

Remember, many lawn diseases can be prevented by following proper cultural practices, and fungicides may not be needed.

Again, Read and follow the instructions for safe mixing and application on the label of each fungicide you use. Pay close attention to the grasses a fungicide can and can't be used on.