Utah State University has identified several common turf diseases affecting lawns in the state, categorizing them by seasonal occurrence. The report outlines specific fungal causes and provides management strategies for spring and summer outbreaks.
Spring fungal disease threats
During the spring, several fungi can impact turf health. Pink snow mold, caused by Fusarium nivalis, often appears as irregular patches with light pink margins and is a major problem in late fall and early spring. To control this, experts suggest avoiding heavy fertilization in the fall and preventing heavy snow accumulations when shoveling.
Managing gray snow mold
Gray snow mold, caused by Typhuyla spp., is a serious issue where persistent snow cover exists. Symptoms include dead patches of grass with brown fungal sclerotia embedded in leaf tissue. Control methods include spreading piles of snow or using black fly ash or graphite to hasten melting.
Controlling melting out symptoms
Melting out, caused by Helminthosporium-like spp., is prevalent every year and is a major cause of dead turf areas. It presents as general thinning of grass with purplish-brown rings around straw-colored spots. Recommended controls include aerating in early spring, avoiding single heavy applications of soluble nitrogen, watering infrequently but deeply, and mowing at 2.5 to 3 inches during hot weather.
Summer disease identification and management
Summer diseases include Necrotic Ring Spot and Summer Patch, both of which can present as dead circles or arcs ranging from several inches to feet in diameter. Necrotic Ring Spot is caused by Ophiosphaerella korrae and is difficult to control even with fungicides. Management involves frequent, low-rate nitrogen applications using acid-type fertilizers like ammonium sulfate.
Managing summer patch outbreaks
Summer Patch, caused by Magnaporthe graminicola, is also difficult to control and can be a serious problem. Similar to Necrotic Ring Spot, management includes aeration, specific mowing heights, and deep, infrequent watering.
Other seasonal fungal occurrences
Other summer occurrences include Fairy Ring, which features a circle of dark green grass with mushrooms, and Powdery Mildew, which causes white powder on leaves in shady areas. For Powdery Mildew, experts recommend avoiding heavy shade by pruning trees and shrubs and planting shade-adapted varieties like fescue.
While some fungicides listed are available for home use, others may require application by a commercial operator or licensed applicator. Utah State University notes that the use of restricted pesticides is the legal responsibility of the applicator and does not endorse specific products.
