There are grass diseases for about every environmental condition we have. Some develop in the winter under the snow while others only occur during the extreme heat of summer. Some grass diseases occur more in wet soils after application of high fertilizer levels while others are brought on by drought and low fertilization levels. Lawn diseases occur when environmental conditions (weather, management, and/or site conditions) become favorable for the buildup of the pathogen populations and/or cause an increase in the susceptibility of the plant. When this happens, turfgrass loss due to lawn diseases can occur. Below are some recommendations that can help limit the chances of your lawn getting a lawn disease or fungus.
Soil compaction can be a contributor to lawn diseases. When soil is compacted to tight it prevents roots from being able to establish growth. It is very common for home owners to place an inch or two of top soil over the compacted soil in hopes of growing a healthy lawn, but this isn't enough. Preparing your soil should include working it into the compacted soil. This will create a deeper rootzone for grass to establish. Just before preparing the soil is a great time to do a soil test to check for proper phosphorus and potassium. Each of these can be added, if needed, when you are preparing your soil. If your soil doesn't have the right phosphorus or potassium levels contact us.
The build up of partially decomposed grass in your lawn is called thatch. Thatch is good but a build up of more than 1/2 inch can cause issues with your lawn. The thick layer of thatch can be a location for fungi to live during the winter which will then grow and attach the turf.
To reduce thatch you can mechanically dethatch your lawn or aerate your lawn. Dethatching involves scraping up your thatch and removing it from your lawn. Aeration removes less thatch but promotes microbial thatch decay for a longer period of time. It also reduces soil compaction, increases water and nutrient penetration and stimulates the development of roots.
Another method of reducing thatch is to apply a uniform layer of thin soil over your lawn, this is called topdressing. The soil organism in the topdressing start to decompose the thatch.
The most effective way to treat compacted soil is to aerate your lawn.
You should try to avoid applying excessive fertilizer in the spring and during hot weather when you are trying to resolve a lawn with symptoms of a lawn disease. Summer moisture stress can often be associated with summer patch development. Therefore, proper watering is critical. If your lawn has a disease or fungus you need to do frequent watering of the top soil so you get 1/2 to 2 inches soil moisture. As the root system redevelops you can increase the amount of watering. Watering during the heat of the day will prevent water stress and reduce associated patch symptom development.
If your lawn has patch disease problems you should mow your lawn higher during this recovery period. This will help the roots to grow deeper allowing them to draw more moisture and nutrients. This is especially important during the hot periods of the summer. Mowing 1 inch of grass from your lawn will help minimize the stress on your lawn.
If you need to reseed portions of your lawn due to a lawn disease select a mixture of grass types, this will result in a more disease tolerant lawn. Overseeding your lawn usually results in minimal value. This is because of the low seed-to-soil contact achieved. If you deside to overseed it is best to either topdress or thoroughly core aerate your lawn before overseeding. This will improve the seed-to-soil contact that is required for good germination and seedling development.
Re-sodding an infected lawn has a high chance of the lawn disease returning and the new sod being damaged. Therefore replacing the affected areas of your lawn may only provide a temporary fix to resolving your lawn disease and not actually treat the real cause.
Applying fungicides to treat your lawn disease should be done along with all the practices listed above. Applying a preventive fungicide to a lawn with a history of disease should be done in early spring and repeat applications made every 3 -4 weeks. Fungicides alone are not a substitute for improved lawn practices.