Turf Disease in Utah

Utah Pest Fact Sheet

USU Extension/Plant Pest Diagnostic Lab

Utah Plant Disease Control No. 17

 Revised March 1998


 

Turf Disease in Utah

Sherman V. Thomson/Extension Plant Pathologist
Scott C. Ockey/Plant Disease Diagnostician
 
 

 
Irregular patches of dead turf.
Irregular patches of dead turf characteristic of both gray and pink snow mold infections. This photo show both types of infection. The circles with a pinkish hue are pink snowmold, those with a lighter (almost bleached) appearance are gray snow mold infections.
Close-up of snow mold infections.

Close-up of snow mold infections. Both gray and pink infections are shown. Those with pink borders are pink snow mold and those lighter infections with less marked lesions are gray snow mold infections.

Spore masses produces by the pick snowmold fungus.
Arrows indicating sporodochia (spore masses) produced by the pink snowmold fungus, Fusarium nivalis.
Hyphal mat produced by the gray snowmold fungus.
Hyphal mat produced by the gray snowmold fungus, Typhula spp. Dead patches of grass, usually with a gray-white hyphal mat are key symptoms of a gray snowmold infection. Also, with small sandgrain-sized brown fungal sclerotia are evident imbedded in the dead leaf tissue.
Patch of infected grass.
Patch of grass infected with the gray snowmold fungus. Affected grass will appear matted.
Advancing border of infected turf.
Advancing border of turf infected with a snowmold fungus. Presence of fungal hyphae (center) indicates an active infection.
Thinning and necrosis of grass.
Thinning and necrosis of grass, common when Melting Out fungi are infecting the plant tissues.
Melting out lesions.
Characteristic Melting Out lesions indicated by the arrows. Lesions are brownish-purple and circular to oval in shape with straw colored centers.
Fairy Ring
Fairy Ring with active fungal reproductive structures (mushrooms). Fairy rings will normally appear in circles or arcs, and radiate out from the initial affected point.
Active edge of the fairy ring.
Circle of dark green grass as indicated by the arrow shows the active edge of the fairy ring. Vegetative portions of the causal fungus will continue to radiate outward periodically producing mushrooms.

SPRING DISEASES

PINK SNOW MOLD

Cause: Fusarium nivalis--fungus

Importance: Major problem in late fall and early spring. Snow cover not necessary.

Symptoms: Irregular patches with light pink margins.

Control:

1. Avoid heavy fertilization in the fall.
2. Avoid heavy snow accumulations when shoveling snow.
3. Apply fungicides to previously affected areas in fall and spring.

Fungicides:* Banner, Bayleton, Chipco 26019, Cleary 3336, Fore, Fungo, Rubigan, Terraclor (PCNB), Thiram, Vorlan


GRAY SNOW MOLD

Cause: Typhuyla spp.--fungus

Importance: A serious problem where persistent snow cover is common.

Symptoms: Dead patches of grass in the spring; presence of sandgrain-sized, brown fungal sclerotia embedded in dead leaf tissue.

Control:

1. Avoid heavy snow accumulations when shoveling snow.
2. Physically spread piles of snow or apply black fly ash or graphite to hasten snow melt.
3. Apply fungicide in late fall where snow mold has been a problem.

Fungicides:* Banner, Bayleton, Chipco 26019, Dyrene, Prostar, Rubigan, Terraclor (PCNB), Thiram


MELTING OUT

Cause: Helminthosporium-like spp.--fungus

Importance: Prevalent every year. Major reason for dead areas in turf.

Symptoms: General thinning of grass. Circular purplish-brown to dark brown rings around straw-colored spots on leaf blades.

Control:

1. Aerate to reduce thatch in early spring.
2. Avoid a single heavy application of soluble nitrogen in the spring.
3. Water infrequently but deeply.
4. Mow at 2.5 - 3 inches during hot weather.
5. Apply fungicide to areas where problem has occurred in previous years.

Fungicides:* Banner, Chipco 26019, Cleary 3336, Curalan, Daconil, Dyrene, Fore, Terraclor (PCNB), Vorlan


SUMMER DISEASES

NECROTIC RINGSPOT

Cause: Ophiosphaerella korrae--fungus

Importance: Can be a serious problem in spring and fall.

Symptoms: Dead circles or arcs that range in size from several inches to several feet in diameter. Microscopic dark hyphae can be found on the grass crowns. Difficult to control even with fungicides.

Control:

1. Aerate to reduce thatch in early spring.
2. Nitrogen fertilizer should be applied frequently and at low rates when the grass is actively growing. Use an acid type fertilizer like ammonium sulfate.
3. Keep mowing height at 2.5 - 3 inches.
4. Water infrequently but deeply.
5. Apply fungicides where necrotic ringspot has been a problem.
6. Replant with several grass species with resistance.

Fungicides:* Chipco 26019, Fungo, Rubigan, Banner Max, Heritage, Eagle, Sentinel


SUMMER PATCH

Cause: Magnaporthe graminicola--fungus

Importance: Can be a serious problem . May be present during the summer.

Symptoms: Dead circles or arcs that range in size from several inches to several feet in diameter, indistinguishable from necrotic ring spot. Microscopic dark hyphae can be found on the grass crowns. Difficult to control.

Control:

1. Aerate to reduce thatch in early spring.
2. Nitrogen fertilizer should be applied frequently and at low rates when the grass is actively growing.
3. Mow at 2.5 - 3 inches.
4. Water infrequently but deeply.
5. Apply fungicide where the disease has occurred.
6. Replant with several grass species with resistance.

Fungicides:* Banner, Bayleton, Fungo, Rubigan, Alamo, Tilt, Sentinel, Intercept, Eagle, Cleary's 3336, Topsin, Heritage, Abound, Fungicide IX.


FAIRY RING

Cause: Various basidiomycete fungi

Importance: Common but only important in a few situations.

Symptoms: Circle of dark green grass with mushrooms forming in the band. Occasionally, the grass dies within the ring.

Control:

1. Keep turf adequately fertilized to promote even turf growth and color.
2. Aerate or use surfactants to improve water penetration into rings. Silicone surfactants work best.
3. If problem is severe, kill grass with glyphosate herbicide, rototil, and replant.
4. Prostar fungicide* provides suppression.


POWDERY MILDEW

Cause: Erysiphe graminis--fungus

Importance: Common but causes minor damage.

Symptoms: White powder on leaves, especially in shady areas.

Control:

1. Do not plant turf in heavy shade.
2. Prune trees and shrubs to enhance light penetration.
3. Water infrequently but deeply.
4. Plant shade-adapted varieties (fescue).
5. Apply fungicides to turf with a history of mildew.

Fungicides:* Banner, Bayleton, Rubigan


*Some of the fungicides listed are not readily available for home lawn use but can be obtained from commercial businesses or applied by a commercial operator.

 

 

Precautionary Statement: All pesticides have benefits and risks, however following the label will maximize the benefits and reduce risks. Pay attention to the directions for use and follow precautionary statements. Pesticide labels are considered legal documents containing instructions and limitations. Inconsistent use of the product or disregarding the label is a violation of both federal and state laws. The pesticide applicator is legally responsible for proper use. This publication is issued in furtherance of Cooperative Extension work. Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Vice President for Extension and Agriculture, Utah State University.