Ohio State University Extension Bulletin

Management of Turfgrass Pests
Weeds, Diseases, and Insects
2003

Bulletin L-187

Management of Turfgrass Diseases

Guide for the Management of Turfgrass Diseases

DISEASE (SEASON) AND/OR
SUSCEPTIBLE TURFGRASS1		 MAINTENANCE
PRACTICES & COMMENTS		 FUNGICIDE/NiATICIDE
ACTIVE INGREDIENT3
Algae All turfgrasses
  1. Reduce shade.
  2. Avoid excessive or low fertilization.
  3. Improve soil drainage.
  4. Alleviate compaction
  5. Mow high to increase density
 Mancozeb, Chlorothalonil
Anthracnose
(Colletotrichum graminicola)		 (Jul-Aug)
ANNUAL BLUEGRASS
Bentgrass
Fine fescue
  1. Fertilize and water to maintain vigor.
  2. Aerate and improve root growth.
Triadimefon, Thiophanate-methyl2 Propiconazole, Fenarimol, Cyproconazole, Azoxystrobin, Trifloxystrobin, Aluminum tris, Polyoxin D zine salt
Bentgrass Deadspot
(Ophiosphaerella agrostis)		 (fall, winter & spring damage is long lasting)
CREEPING BENTGRASS
  1. May occur on the newer creeping bentgrass cultivars.
  2. A newly identified disease; research is being conducted on how to manage.
Fludioxonil, Aluminum tris, Boscalid, Pyraclostrobin, Fludioxonil
Brown Patch - See Rhizoctonia blight
Dollar Spot
(Lanzia and Moellerodiscus, spp. formerly Sclerotinia homeocarpa)		 (Late Jun-Oct)
BENTGRASSES
BLUEGRASSES
Fescues
Ryegrasses
  1. Avoid nitrogen deficiency.
  2. Remove dew from greens by dragging with a hose or pole.
  3. Choose resistant grass varieties.
Chlorothalonil, Vinclozolin2, Fenarimol, Iprodione2, Propiconazole, Cyproconazole, Thiophanate-methyl2,Thiram, Triadimefon, Myclobutanil
Fairy Rings
(Basidiomycete soil fungi)		 (April-Oct.)
BENTGRASSES
BLUEGRASSES
Fescues
Ryegrasses
  1. Remove infested sod and soil, replace with clean soil and reseed or sod.
  2. Improve water penetration.
  3. Increase nitrogen fertilization to mask symptoms.
Methyl bromide fumigation will eradicate fungus but will also kill turf. Flutolanil, Pyraclostrobin, Azoxystrobin
Fusarium Blight - see Necrotic Ring Spot and Summer Patch
Fusarium Patch - see Pink Snow Mold/ Fusarium Patch (When disease occurs without snow, it is referred to as Fusarium Patch.)
Gray Leaf Spot
(Pyricularia grsiea)		 (Aug.-Oct)
PERENNIAL RYEGRASS
  1. Avoid excessive nitrogen
  2. Avoid excessive watering.
  3. Avoid excessive herbicide use.
Azoxystrobin, Thiophanate-methyl, Chlorothalonil, Propiconazole, Trifloxystrobin, Triadimefon, Polyoxin D zine salt
Gray Snow Mold/
Typhula Blight
(Typhula spp.)		 (Nov.-April)
Fine fescue
BENTGRASSES
ANNUAL BLUEGRASS
Kentucky bluegrass
Tall fescue, Perennial ryegrass
  1. Avoid heavy fall nitrogen promoting late lush growth.
  2. Rake leaves and cut short.
  3. Control drifting snow.
Triadimefon, Chloroneb, Pentachloronitrobenzene, Thiram, Cyproconazole, Iprodione, Iprodione +, Pyraclostrobin, Chlorothalonil, Flutolanil, Azoxystrobin, Fludioxonil
Leafspot/Blight/Melting Out
(Drechsler & Bipolaris spp.)		 (leafspot: spring & fall)
(blight & melting out:
April-Oct.)
KENTUCKY BLUEGRASS
BENTGRASSES
FINE FESCUE
Ryegrasses, Tall fescue
  1. Raise cutting height.
  2. Avoid excessive nitrogen.
  3. Avoid light, frequent watering.
  4. Avoid excessive herbicide.
Iprodione, Chlorothalonil, Maneb, Mancozeb, Pyraclostrobin, Vinclozolin, Myclobutanil, Pentachloronitrobenzene, Azoxystrobin, Trifloxystrobin, Fludioxonil, Polyozin D zine salt
Nematodes (summer & fall)
All turfgrasses		   Fenamiphos, Ethoprop
Necrotic Ring Spot4
(Leptosphaeria korrae)		 (spring to fall)
KENTUCKY BLUEGRASS
(especially 3-4 year old sod)
Annual bluegrass
Fine Fescue
  1. Avoid low mowing heights (below 2 inches).
  2. Reduce excessive thatch (over 3/4 inch), compaction and frequently aerate.
  3. Use Kentucky bluegrass and perennial ryegrass mixtures.
  4. Improve soil drainage.
  5. Avoid excessive watering or drought stress.
  6. Use slow release nitrogen.
Fenarimol, Propiconazole, Iprodione, Thiophanate-methyl, Cyproconazole, Myclobutanil, Azoxystrobin
Pink Patch5
(Limonomyces roseipellis)		 (spring & fall)
Bentgrasses
FINE FESCUE
PERENNIAL RYEGRASS		 Follow balanced fertilization program. Mancozeb, Flutolanil, Azoxystrobin, Pyraclostrobin
Pink Snow Mold/
Fusarium Patch
(Microdochium nivale)		 (Nov.-April)
Bluegrasses
Bentgrasses
Fescues
Ryegrasses
  1. Avoid excessive late fall fertilizing.
  2. Rake leaves and mow short.
  3. Control drifting snow.
 Triadimefon, Fenarimol, Iprodione2, Mancozeb, Azoxystrobin Pentachloronitrobenzene, Thiram, Thiophanate-methyl2, Vinclozolin, Cyproconazole, Trifloxystrobin, Fludioxonil, Pyraclostrobin, Polyoxin D zinc salt
Powdery Mildew
(Erysiphe graminis)		 (July-Oct.)
KENTUCKY BLUEGRASS
Fine fescue
  1. Reduce shade.
  2. Increase air circulation by removing surrounding vegetation.
  3. Use resistant Kentucky bluegrass varieties.
 Triadimefon, Fenarimol, Propiconazole, Cyproconazole, Myclobutanil, Pyraclostrobin
Pythium Blight
(Pythium aphanidermatum,
P. graminicola)		 (June-Sept.)
BENTGRASSES
ANNUAL BLUEGRASS
PERENNIAL RYEGRASS
Kentucky bluegrass
  1. Improve soil drainage.
  2. Increase air circulation by removing surrounding vegetation.
  3. Avoid mowing wet grass.
  4. Avoid excess watering.
 Chloroneb, Etridiazole, Propamocarb, Metalaxyl, Fosetyl-Al, Mancozeb, Aluminum tris, Azoxystrobin, Mefenoxam
Pythium Root Rot
(Pythium)		 (spring & fall)
ANNUAL BLUEGRASS
BENTGRASSES
  1. Improve soil drainage.
  2. Increase mowing height.
 Metalaxyl, Propamocarb, Apply Oct-Nov, water in thoroughly. Azoxystrobin, Mefonoxam
Red Leaf Spot
(Drechslera erythrospila)		 (June-Sept.)
BENTGRASSES
  1. Remove clippings.
  2. Fertilize to maintain vigor.
 Iprodione, Vinclozolin, Chlorothalonil
Red Thread
(Laestisaria fuciformis)		 (all seasons)
PERENNIAL RYEGRASS
FINE FESCUE
Bentgrasses
Annual bluegrass
Kentucky bluegrass
  1. Follow balanced fertilization program.
  2. Promote growth by aeration, watering, etc.
 Vinclozolin, Flutolanil, Iprodione Chlorothalonil, Cyproconazole, Thiophanate-methyl, Mancozeb, Triadimefon, Propiconazole, Myclobutanil, Polyoxin D zine salt, Azoxystrobin, Pyraclostrobin, Trifloxystrobin
Rhizoctonia Blight/
Brown Patch
(Rhizoctonia solani,
= Thanatephorus cucumeris)6		 (July-Aug.)
TALL FESCUE
BENTGRASSES
PERENNIAL RYEGRASS
Kentucky bluegrass
Fine fescue
  1. Avoid excessive nitrogen fertilization.
  2. Increase air circulation by removing surrounding vegetation.
  3. Avoid excessive watering.
 Anilazine, Chlorothalonil, Mancozeb, Maneb, Propiconazole, Iprodione, Pentachloronitrobenzene, Thiram Triadimefon, Thiophanate-methyl3, Cyproconazole, Trifloxystrobin Myclobutanil, Azoxystrobin, Fludioxonil, Polyoxin D zine salt, Pyraclostrobin
Rust
(Puccinia spp.)		 (Aug.-Oct.)
PERENNIAL RYEGRASS
KENTUCKY BLUEGRASS
  1. Avoid nitrogen deficiency.
  2. Use resistant varieties of Kentucky bluegrass and perennial ryegrass.
  3. Water if dry, promote growth.
 Mancozeb, Propiconazole, Cyproconazole, Chlorothalonil, Triadimefon, Fenarimol, Myclobutanil, Pyraclostrobin, Trifloxystrobin
Seedling Disease
(="damping-off")
(primary pathogens are
Pythium and Rhizoctonia)		 (mainly in summer)
all grasses
  1. The primary concern is seeding in hot, wet summer conditions.
  2. Manage watering to prevent waterlogged soil.
 See fungicides listed under Pythium Blight and Rhizoctonia Blight/ Brown patch. Seed may be treated with Mefenoxam (Apron) for Pythium.
Slime Molds
(Myxomycete)		 (Aug.-Sept.)
All Turfgrasses		 Remove mechanically by mowing or raking. Mancozeb
Snow Mold - see Gray Snow Mold and Pink Snow Mold
Stripe Smut
(Ustilago striiformis)		 (spring & fall)
KENTUCKY BLUEGRASS
bentgrasses
  1. Avoid drought stress.
  2. Avoid excess nitrogen.
  3. Use resistant varieties of Kentucky bluegrass.
 Propiconazole, Triadimefon, Myclobutanil, Cyproconazole Note: Apply extra water for crown penetration. Apply in late fall or early spring.
Summer Patch4
(Magnaporthe poae,
formerly Phialophora
graminicola)		 (June-Aug.)
ANNUAL BLUEGRASS
KENTUCKY BLUEGRASS
Fine fescue
  1. Avoid low mowing and thatch buildup.
  2. Maintain soil pH between 6 & 7.
  3. Light, frequent watering during dry periods to reduce heat stress.
  4. Use slow-release nitrogen.
  5. Use Kentucky bluegrass and perennial ryegrass mix.
  6. Avoid compaction.
 Fenarimol, Triadimefon, Propiconazole, Cyproconazole, Myclobutanil, Azoxystrobin Trifloxystrobin, Fludioxonil, Pyraclostrobin Note: above materials must be applied preventively. Thiophanate-methyl Note: Thiophanate-methyl works best as a curative application.
Take-all Patch
(Gaeumannomyces
graminis)		 (spring & fall)
BENTGRASSES
  1. Use acidifying fertilizers to lower pH.
  2. Avoid heavy rates of lime.
  3. Remove patches and resod.
  4. Avoid excess nitrogen fertilization.
 Fenarimol., Triadimefon, Propiconazole, Azoxystrobin, Pyraclostrobin
Typhula blight - see Gray Snow Mold/ Tiphula Blight
Yellow Patch
(Rhizoctonia cerealis)		 Bluegrasses
Bentgrasses
  1. Reduce excessive thatch.
  2. Avoid excessive watering.
  3. Improve soil drainage.
 Flutolanil, Azoxystrobin, Fludioxonil, Polyoxin D zine salt
Yellow Tuft/
Downy mildew
(Sclorophthora spp.)		 (spring & fall)
Bentgrasses		 Improve soil and surface drainage. Metalaxyl, Fosetyl-Al, Aluminum tris
1 Grass types listed in capital letters have been observed to be especially susceptible to the pathogen.
2 Continued or sole use of these materials may favor buildup of resistant fungal population.
3 Products containing these active ingredients are listed in the following table. Read the product label to see if it is labeled for the disease of concern. The degree of control may vary with different products.
4 Necrotic ring spot and summer patch are known to cause symptoms once attributed solely to Fusarium blight.
5 Pink patch is a distinct disease from red thread. There are few fungicides specifically registered for control of pink patch
6 Another fungus, Rhizoctonia zeae, is also capable of causing brown patch-like symptoms on bluegrass and bentgrass. Benzimidazole fungicide (Thiophanate-methyl) is not effective against this pathogen.

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