Lawn diseases are frequently mismanaged. More often than not, when some of these disease crop up, people assume it is the result of lack of water. They will frequently try to combat dying patches of grass with more frequent watering, which often does more harm than good because the primary cause of lawn diseases are fungal diseases that thrive in damp lawns. The UGA guide offers symptoms and solutions to some of the most common lawn diseases seen in lawns in the Southeast.
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The University of Georgia Cooperative Extension is committed to educating the people of Georgia throughout their lifetimes through unbiased and research-based learning. They are funded by the county, the state, and the country supported by specialists whose expertise lies in agriculture and environmental sciences.
Lawn Disease Research Covered
This research guide from UGA provides users with a variety of useful information including:
It generally thrives in humid conditions with minimum temperatures of 65 degrees. It is identified through areas of blighted grass ranging in size from a few inches to many feet. Correcting irrigation as well as adjusting fertilizer applications to lower nitrogen and increased amounts of phosphorus can help fight brown patch.
All species of grass can become infected with this fungus, and it thrives in dry soil with low nitrogen. It can be identified by smaller areas of blighted grass in circular patterns. Fertilizing as necessary as well as adjusting irrigation, reducing thatch, and increasing circulation can help with dollar spot abatement.
The fungus thrives in overly moist conditions and cooler temperatures. In early stages, grass can appear dark and water-soaked and in later stages white, cottony mycelium can be seen on affected turf. Infected turf will appear oily and matted and die quickly. Combating pythium can be accomplished through correcting watering and irrigation issues, infrequent mowing, improving circulation, and applying fertilizers as necessary.
Caused by both Drechslera spp. and Bipolaris spp, this turf disease appears as small dark spots on grass blades or sheaths. Low potassium, high nitrogen, and over-irrigating can create ideal conditions for this disease. To fight this disease, increase air circulation to promote drying, reduce thatch, and apply fungicides as needed.
This fungus is similar to Helminthorium, but is a weaker strain. It typically only affects turf that is already heat stressed. Symptoms vary depending on the type of grass, but usually involves a dappling of color on the blade. Abatement involves soil testing, removing thatch, and mowing during dormancy while removing clippings. Fungicides are also recommended for treating infected turf.
High humidity, warm temperatures, and high nitrogen levels are the conditions in which Pyricularia grisea thrives. It first appears as small, gray spots on blades. Control involves avoiding high levels of nitrogen and irrigating infrequently but deeply. Fungicides can also be used as necessary to eradicate gray leaf spot.
It sounds more magical than it is–fairy ring is caused by various mushroom-producing fungi. Infected grass will appear as circular bands of dark green grass with the grass inside the ring appearing to wither and wilt. During excessively damp conditions, mushrooms may also appear. To fight fairy rings, aerating affected areas and deeply saturating the area will help dilute the mushroom toxins.
This disease occurs in soils with pH above 6.5 and is more severe on sandy soils. It is identified by circular patches of brown or bronze-colored grass with dark brown roots. Applying acidifying fertilizers with high levels of phosphorus, potash, and other minor elements along with reducing the use of lime can help improve health of infected grass. Increased air circulation and improved drainage as well as applying fungicides as recommended can also help eliminate this disease.
Damp, shady areas are susceptible to rust. The infection presents as light yellow flecks on grass which develop into larger “blisters”. These blisters rupture and release a yellowish-orange or brownish-orange spores. To control rust, applying nitrogen as necessary and reducing thatch and irrigation are critical as well as applying recommended fungicides.
This infection is most common during wet, rainy weather. Spores appear as black, bluish-gray, yellow, or tan fruiting bodies. The disease does not usually kill grass or turf, but if it is severe enough, it can shade grass enough to cause it to die. Eliminating slime molds requires mowing, raking, and removing the fungus. Typically, dry conditions will help it resolve on its own.
This type of infestation occurs through various different species. Nematodes can infiltrate just about any type of soil in any type of season. They attack the root system of turf and suck nutrients and vitality from grass. Combating nematodes can be difficult, but sending soil samples to be tested can identify a specific strain of nematodes. In most cases, simply feeding and nourishing infected turf is the only course of treatment.
Turf that is stressed can be more susceptible to different types of fungal infections. Correcting irrigation issues as well as making sure your lawn is properly fertilized and cut properly can help improve conditions for lawns and help make them more resistant to disease. The UGA Extensions offer a whole host of information on the best way of caring for your turf to keep it supple and vibrant all season long.