Plant Diseases Chapter 4 Section VII of the Pest Bear & Affiliates Service Personnel Development Program 2005 2005-2006, Central Fla Duplicating,

Select the disease you wish to learn about by “clicking” on the respective title in the Table of Contents on the following page. Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Brown Patch - Environment Night temperature > 60°F for cool season grasses and 50- 60°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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Fairy Ring - Environment Light to moderate textured soils are favored Soil usually has a pH of 5-7.5 Low to moderate soil moisture Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Powdery Mildew - Environment Disease is severe in shaded areas at temperatures of 60-72 degrees F High humidity is required for infection, but leaf wetness is not essential Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Helminthosporium Leaf Spot - Environment Temperatures of 77-95 degrees F Disease severity increases with increases in temperature More than 10 hours of leaf wetness per day for several days Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Rust - Environment Temperatures of 68-86 degrees F Disease is severe un turf subjected to drought stress, low mowing, shade, or poor air circulation Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Pink Snow Mold - Hosts All cool season turfgrasses Bentgrass, annual bluegrass and perennial ryegrass are particularly susceptible Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Summer Patch - Hosts Bluegrasses and fine-leaf fescues

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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Stripe Smut - Environment Infection occurs at 50-68 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 Copyright @ 2005-2006, 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 Copyright @ 2005-2006, Central Fla Duplicating, Inc. All rights reserved

Plant Diseases Chapter 4 Section VII of the Pest Bear & Affiliates Service Personnel Development Program 2005 2005-2006, Central Fla Duplicating,

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Plant Diseases Chapter 4 Section VII of the Pest Bear & Affiliates Service Personnel Development Program 2005 2005-2006, Central Fla Duplicating,

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