Plant Diseases Chapter 4 Section VII of the Pest Bear & Affiliates Service Personnel Development Program , Central Fla Duplicating, Inc. All rights reserved

Select the disease you wish to learn about by “clicking” on the respective title in the Table of Contents on the following page , Central Fla Duplicating, Inc. All rights reserved

To properly understand the diseases affecting turf, you must understand five things about each disease: 1)Who the host or hosts are 2)What is the pathogen that causes the disease 3)How do you make a diagnosis of the disease 4)What environmental factors are favored by the disease 5)How can the disease be controlled using management cultural controls , Central Fla Duplicating, Inc. All rights reserved

Contents Anthracnose Brown Patch Dollar Spot Fairy Ring Gray Leaf Spot Gray Snow Mold Helminthosporium Necrotic Ring Spot Nematodes Pink Snow Mold Powdery Mildew Pythium Blight Red Thread Rust Spring Dead Spot Stripe Smut Summer Patch Take-All Patch , Central Fla Duplicating, Inc. All rights reserved

Anthracnose , Central Fla Duplicating, Inc. All rights reserved

Anthracnose - Hosts Creeping bentgrass Bluegrass Fescue Perennial ryegrass Bermudagrass Centipedgrass St Augustinegrass , Central Fla Duplicating, Inc. All rights reserved

Anthracnose - Hosts Annual Bluegrass is particularly susceptible , Central Fla Duplicating, Inc. All rights reserved

Anthracnose - Pathogen Colletotrichum graminicola , Central Fla Duplicating, Inc. All rights reserved

Anthracnose - Diagnosis Grass turns yellow to brown in irregular shaped patches of turf Leaf lesions are yellow with black centers Brown to black hairs (setae) may be observed on leaves or crown with aid of 10x magnification , Central Fla Duplicating, Inc. All rights reserved

Anthracnose - Environment Found in temperatures >78° F More than 10 hours of leaf wetness per day for several days Particularly severe on turf exposed to soil compaction and excessive thatch Pathogen may cause crown rot in creeping bentgrass at temperatures of 60°-77°F , Central Fla Duplicating, Inc. All rights reserved

Anthracnose – Management cultural controls Disease will be more severe under low nitrogen conditions Maintain balanced fertility throughout the growing season Use light weight mowing equipment to reduce compaction Limit thatch thickness Decrease shade and increase air circulation to reduce wetness Avoid irrigation in late afternoon or evening prior to midnight , Central Fla Duplicating, Inc. All rights reserved

Anthracnose Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Brown Patch , Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Hosts All common turfgrass species are susceptible to Brown Patch , Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Pathogen Rhizoctonia solani , Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Diagnosis Cool-season turfgrasses: circular patches of brown turf a few inches to several feet in diameter Leaves have gray, irregular- shaped lesions with thin brown borders Patches are surrounded by smoky-colored ring or mycelium on close-cut turf , Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Diagnosis Warm-season turfgrasses: leaf sheathes at margins of patches are brown to black Dark brown lesions may be visible on stolons , Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Environment Night temperature > 60°F for cool season grasses and °F for warm season grasses More than 10 hours of leaf wetness per day for several days Disease is severe at low mowing heights Disease can be severe on poorly drained soils , Central Fla Duplicating, Inc. All rights reserved

Brown Patch– Management cultural controls Disease may be more severe on lush turf with excessive nitrogen and low phosphorus and potassium Maintain balanced fertility throughout the growing season Decrease shade and increase air circulation to enhance drying of the turf Avoid irrigation in late afternoon or in evening prior to midnight Limit thatch thickness Mow at recommended height , Central Fla Duplicating, Inc. All rights reserved

Brown Patch Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot - Hosts All common turfgrass species are hosts for Dollar Spot , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot - Pathogen Sclerotinia homeocarpa , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot - Diagnosis Straw-colored patches of turf 1-3 inches in diameter White mycelium may be associated with patches when turf is wet Straw-colored lesions extend across leaf blades , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot - Environment Night temperatures > 50°F and day temperatures < 90 °F More than 10 hours of leaf wetness per day for several days Disease is severe on turf which is subjected to drought stress , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot – Management cultural controls Disease may be more severe under low nitrogen fertility Maintain balanced fertility throughout the growing season Limit thatch thickness Decrease shade and increase air circulation to enhance drying of the turf Avoid irrigation in late afternoon or in evening prior to midnight Avoid drought stress , Central Fla Duplicating, Inc. All rights reserved

Dollar Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring - Hosts All common grass species are hosts for Fairy Ring , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring - Pathogen Several species of “mushroom- forming” fungi , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring - Diagnosis Circles or arcs of mushrooms or wilted, dead or dark green turf White mats of fungal mycelium may be found in thatch or soil associated with circles or arcs , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring - Environment Light to moderate textured soils are favored Soil usually has a pH of Low to moderate soil moisture , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring – Management cultural controls Maintain moderate nitrogen fertility Maintain moderate to high levels of phosphorus and potassium according to soil tests Excavate ring and soil 12 inches deep and 24 inches beyond ring or arch and replace with new soil Remove sod, cultivate soil 6-8 inches deep in several directions, add wetting agent to soil, reseed or sod , Central Fla Duplicating, Inc. All rights reserved

Fairy Ring Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Nematodes , Central Fla Duplicating, Inc. All rights reserved

Nematodes - Hosts All common grass species are hosts for nematodes , Central Fla Duplicating, Inc. All rights reserved

Nematodes - Pathogen More than 15 different species of nematodes attack turfgrasses , Central Fla Duplicating, Inc. All rights reserved

Nematodes - Diagnosis Irregular shaped light green or yellow patches of turf which may be several feet in diameter Leaves may be yellow or brown from the tip Roots may be thin, stunted or knotted , Central Fla Duplicating, Inc. All rights reserved

Nematodes - Environment Soil temperatures of >40° F Symptoms are often severe on turf growing in sandy or light-textured soils Symptoms may be enhanced by drought and high temperatures of >80°F , Central Fla Duplicating, Inc. All rights reserved

Nematodes – Management cultural controls Maintain balanced fertility throughout the growing season Maintain moderate to high levels of phosphorus and potassium according to soil tests Have soil analyzed for nematodes prior to seeding or sodding Use sod that is nematode free , Central Fla Duplicating, Inc. All rights reserved

Nematodes Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight - Hosts All common turfgrass species are susceptible to Pythium Blight , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight - Pathogen Pythium aphanidermatum and other species of Pythium , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight - Diagnosis Greasy brown patches of turf an inch or less in diameter, increasing to several inches and turning straw colored Grey-white, cottony mycelium observed in the early morning , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight - Environment Night temperature > 65°F More than 10 hours of leaf wetness per day for several days Poor surface and subsurface drainage , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight– Management cultural controls Disease may be more severe under excessive nitrogen conditions Maintain balanced fertility throughout the growing season Maintain optimum plant calcium levels Decrease shade and increase air circulation to enhance drying of the turf Avoid irrigation in late afternoon or in evening prior to midnight Improve surface and subsurface drainage Avoid mowing when surface is wet , Central Fla Duplicating, Inc. All rights reserved

Pythium Blight Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold , Central Fla Duplicating, Inc. All rights reserved

All cool season grasses Bentgrass Annual Bluegrass Perennial Ryegrass Gray Snow Mold - Hosts , Central Fla Duplicating, Inc. All rights reserved

Bentgrass, Annual Bluegrass, and Perennial Ryegrass are particularly susceptible Gray Snow Mold - Hosts , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold - Pathogen Typhula incarnate Typhula ishikarensis , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold - Diagnosis Circular straw-colored patches of turf usually less than 10” in diameter, evident after the snow melts Orange, brown to black sclerotia form on leaves , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold - Environment Snow-cover is required for disease to develop Disease is severe when snow cover exceeds 90 days , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold – Management cultural controls Avoid a fertility program that results in lush, fast-growing turf in late fall or winter Maintain potassium levels according to soil tests Prevent snow from accumulating excessively on turf areas Prevent compaction of snow and remove snow in the spring Use dark-colored fertilizer to melt snow in the spring , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot - Hosts Kentucky bluegrass Fine-leaf fescue , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot - Pathogen Leptosphaeria korrae , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot - Diagnosis Light-green to yellow patches of turf 3-5” in diameter Light-green turf turns brown to straw-colored Roots and rhizomes are brown to black , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot - Environment Initiates at temperatures <80 degrees F in moist soil Severity of symptoms increases with drought and temperatures >80 degrees F Disease may be very severe in compacted soils , Central Fla Duplicating, Inc. All rights reserved

Necrotic Ring Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot - Hosts Bermudagrass , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot - Pathogen Species of Leptosphaeria, Ophiosphaerella, and Gaeumannomyces , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot - Diagnosis Circular patches of straw-colored turf up to several feet in diameter Evident after winter dormancy Roots at edges of patches are dark brown to black , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot - Environment Disease is severe when the average daily temperature in November is <60 degrees F Poor surface and sub-surface drainage Thatch is > ½ inch thick , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot– Management cultural controls Maintain good potassium and low nitrogen levels in the late summer and early fall Maintain a balanced fertility throughout the growing season Maintain moderate to high levels of phosphorus, potassium, and minor elements according to soil tests Improve surface and sub-surface drainage Limit thatch thickness , Central Fla Duplicating, Inc. All rights reserved

Spring Dead Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Red Thread , Central Fla Duplicating, Inc. All rights reserved

Red Thread - Hosts Bentgrass Bluegrass Fine-leaf fescue Perennial ryegrass , Central Fla Duplicating, Inc. All rights reserved

Red Thread - Hosts Fine-leaf fescue, and Perennial Ryegrass are particularly susceptible , Central Fla Duplicating, Inc. All rights reserved

Red Thread - Pathogen Laetisaria fuciformis , Central Fla Duplicating, Inc. All rights reserved

Red Thread - Diagnosis Red-brown patches of turf 1-4” in diameter Pink-red mycelium grows from the tip of the infected leaf blades , Central Fla Duplicating, Inc. All rights reserved

Red Thread - Environment Cool temperatures, degrees F More than 10 hours of leaf wetness per day for several days , Central Fla Duplicating, Inc. All rights reserved

Red Thread– Management cultural controls Disease is more severe with low nitrogen fertility Maintain balanced fertilization throughout the growing season Maintain moderate to high levels of potassium and phosphorus Avoid irrigations in late afternoon or evening Mow at least once each week and remove diseased portion of leaf blades , Central Fla Duplicating, Inc. All rights reserved

Red Thread Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew - Hosts Kentucky bluegrass Fine-leaf fescue Bermudagrass , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew - Pathogen Erysiphe gramminis , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew - Diagnosis White,powdery masses of fungal spores scattered over the surface of the leaves , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew - Environment Disease is severe in shaded areas at temperatures of degrees F High humidity is required for infection, but leaf wetness is not essential , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew– Management cultural controls Disease is more severe under excessive nitrogen conditions Maintain a balanced fertility program throughout the growing season Reduce shade and increase air circulation Plant shade tolerant grass , Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot - Hosts Bluegrass Bentgrass Fescue Perennial ryegrass Bahiagrass Bermudagrass Zoysia Buffalograss , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot - Pathogen Bipolaris sps , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot - Diagnosis Round to oval chocolate-brown spots on the leaves Spots may have tan centers , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot - Environment Temperatures of degrees F Disease severity increases with increases in temperature More than 10 hours of leaf wetness per day for several days , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot – Management cultural controls Avoid excessive nitrogen and maintain a balanced fertility in the growing season Decrease shade and increase air circulation to enhance drying of the turf Avoid late afternoon or evening irrigation Limit thatch thickness and mow at recommended heights Use light-weight mowing equipment to reduce stress Plant resistant grasses , Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf Spot , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf spot - Hosts Most warm season turfgrasses St Augustine is particularly susceptible Ryegrasses and fescues may exhibit severe symptoms under prolonged warm, wet conditions , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf Spot - Pathogen Pyricularia grisea , Central Fla Duplicating, Inc. All rights reserved

Gray Snow Mold - Diagnosis Round or oval gray spots on the leaves Spots surrounded by brown or yellow border Leaves may be blighted gray, usually from the tip downward , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf spot - Environment Night temperatures of >70 degrees F More than 10 hours of leaf wetness per day for several days Disease is severe in shaded areas or during periods of extended overcast weather , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf Spot – Management cultural controls Disease is more severe under excess nitrogen fertility Maintain a balanced fertility throughout the growing season Decrease shade and increase air circulation to enhance drying of turf Avoid irrigation in late afternoon and evening prior to midnight , Central Fla Duplicating, Inc. All rights reserved

Gray Leaf Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Rust , Central Fla Duplicating, Inc. All rights reserved

Rust - Hosts All common species of turfgrasses , Central Fla Duplicating, Inc. All rights reserved

Rust - Pathogen Several species of Puccinia and Uromyces , Central Fla Duplicating, Inc. All rights reserved

Rust - Diagnosis Red-brown powdery masses of spores on leaf blades or leaf sheaths , Central Fla Duplicating, Inc. All rights reserved

Rust - Environment Temperatures of degrees F Disease is severe un turf subjected to drought stress, low mowing, shade, or poor air circulation , Central Fla Duplicating, Inc. All rights reserved

Rust– Management cultural controls Disease is more severe under low nitrogen conditions Maintain a balanced fertility throughout the growing season Reduce shade and increase air circulation Mow at recommended heights Avoid drought stress Avoid irrigation in late afternoon and in evening prior to midnight , Central Fla Duplicating, Inc. All rights reserved

Rust Spot Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold - Hosts All cool season turfgrasses Bentgrass, annual bluegrass and perennial ryegrass are particularly susceptible , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold - Pathogen Microdochium nivale , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold - Diagnosis Salmon colored to red- brown patches of turf 1- 8 inches or more in diameter Common after 60 days or more of snow cover , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold - Environment Disease is common after at least 60 days of snow cover Pathogen can infect turf without snow cover Disease is particularly severe when snow covers unfrozen ground , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold – Management cultural controls Disease is more sever on fast-growing lush turf that receives high nitrogen and low potassium in the fall Maintain balanced fertility Prevent snow compaction and prevent snow from accumulating Melt snow in spring with organic fertilizers Avoid applications of lime Avoid irrigation at night and mow at the recommended height , Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Summer Patch , Central Fla Duplicating, Inc. All rights reserved

Summer Patch - Hosts Bluegrasses and fine-leaf fescues

Summer Patch - Pathogen Magnaporthe poae , Central Fla Duplicating, Inc. All rights reserved

Summer Patch - Diagnosis Circular patches of wilted straw-colored turf Usually less than 10 inches in diameter Leaves turn yellow or brown starting at the tip Roots are light to dark brown , Central Fla Duplicating, Inc. All rights reserved

Summer Patch - Environment Day-time temperature >85 degrees F High soil moisture Poor surface or subsurface drainage Low mowing height , Central Fla Duplicating, Inc. All rights reserved

Summer Patch– Management cultural controls Maintain balanced fertility throughout the growing season Improve surface and subsurface drainage Reduce compaction Syringe turf with water when temperature >85 degrees F Mow at recommended height Prevent stress , Central Fla Duplicating, Inc. All rights reserved

Summer Patch Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch - Hosts Only bentgrasses are highly susceptible , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch - Pathogen Gaeumannomyces graminis , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch - Diagnosis Wilted to bronze or brown circular patches of turf up to several feet in diameter Roots along margins of patches are dark brown , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch - Environment Disease develops rapidly on cool, wet soils with pH >5.5 Disease can be more severe on sandy soils , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch – Management cultural controls Disease is more severe under low or unbalanced fertility conditions Fertilize with acid-forming sources of nitrogen such as sulfur coated urea Maintain moderate to high levels of phosphorus, potassium and minor elements according to soil tests Improve surface and subsurface drainage Avoid use of lime if soil pH >5.0 Avoid heavy, frequent irrigation , Central Fla Duplicating, Inc. All rights reserved

Take-All Patch Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut - Hosts Bluegrass Bentgrass Fescue Perennial ryegrass Tall fescue , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut - Pathogen Ustilago striformis , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut - Diagnosis Yellow to black stripes from tips to base of leaf blade Black masses of spores form along the stripes Leaves turn brown from tips down and tips of leaves twist and curl , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut - Environment Infection occurs at degrees F Sever symptoms are evident during drought and temperatures of >75 degrees F Symptoms are often more severe on acid soils and on turf with excessive thatch , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut – Management cultural controls Disease is more severe on lush, overfertilized or thin, underfertilized turf Maintain a balanced fertility throughout the growing season Avoid drought stress Apply lime if pH is <6 Limit thatch thickness Mow to recommended heights , Central Fla Duplicating, Inc. All rights reserved

Stripe Smut Completed Return to Contents , Central Fla Duplicating, Inc. All rights reserved