Turfgrass Diseases
Turfgrass Disease Disease: normal development disturbed; reduces value
Turfgrass Disease Symptom: visible reaction to a disease
Turfgrass Disease Abiotic: non-living causes
Turfgrass Disease Abiotic: Herbicide
Turfgrass Disease Abiotic: Scalping
Turfgrass Disease Abiotic: Dull Mower
Turfgrass Disease Abiotic: Nutrient
Turfgrass Disease Abiotic: Fertilizer
Turfgrass Disease Abiotic: Cold
Turfgrass Disease Biotic: living organisms, infectious Fungus…
Environment Temperature Fungus in the host unnoticed until the host is under stress
Environment Moisture Rain Dew Irrigation Poor drainage is critical
CULTURAL CONTROL DRAINAGE! Most important
CULTURAL CONTROL Disease-resistant turf Correct species or resistant cultivar
CULTURAL CONTROL Diversify the genetic resistance Blends: mixing cultivars of a species Mixes: mixing species of turf
CULTURAL CONTROL Proper turfgrass establishment At least 6” of topsoil Properly graded with good drainage
CULTURAL CONTROL Mowing Mow within correct height Good cut
CULTURAL CONTROL Irrigation Avoid irrigating in the evening Early morning to knock off the dew Deeply and infrequently
CULTURAL CONTROL Nutritional status Influences diseases Excessive N favors Pythium and Brown Patch
CULTURAL CONTROL Nutritional status Deficient N favors Dollar Spot and Rust
CULTURAL CONTROL Nutritional status Potassium helps environmental stress Use K in a the same proportions as N
CULTURAL CONTROL Thatch control Thatch can support some diseases
BIOLOGICAL CONTROL None used commercial with great success
FUNGICIDE Preventative: applied prior to favorable conditions at lower rates Curative: applied after symptoms have occurred at higher rates
FUNGICIDE Contacts: form preventative coating
FUNGICIDE Contacts New leaves have no protection Fungicide degrades under irrigation, sunlight, mowing Effective for 7 to 14 days
FUNGICIDE Contacts Broad spectrum controls mostly foliar diseases and not root/crown diseases
FUNGICIDE Penetrant Protective and curative Effective for 15 to 30 days
FUNGICIDE Penetrant Specific MOA, develops resistant strains Some chemicals are mixes to take advantage of both the contact and systemic effects
Brown Patch Causal Agent: Rhizoctonia
Brown Patch Hosts: zoysia, St. Augustine, centipede
Brown Patch Favorable Conditions: Spring and fall months Start watching in August
Brown Patch Symptoms: Smoke ring on greens No leaf spots, leaf sheath rot at base
Brown Patch Symptoms: Shoots pull off from stolons easily Roots not affected
Brown Patch Controls: Avoid excess N Improve drainage
Gray Leaf Spot Host: St. Augustine
Gray Leaf Spot Favorable Conditions: Mid-July Shade
Gray Leaf Spot Symptoms: All aboveground plant parts
Gray Leaf Spot Control: Collect clippings Raise mowing height
Dollar Spot Host: bermuda, zoysia
Dollar Spot Favorable Conditions: Warm weather, 60 to 80 F Low N Thatch
Dollar Spot Symptoms: Leaf lesions band across leaf with purple border
Dollar Spot Symptoms: White patches in dew fungus
Dollar Spot Control: Apply N
Dollar Spot Control: Apply N
Fairy Rings Causal Agent: fungi
Fairy Rings Favorable Conditions: Soils with high OM Frequently old tree stumps
Fairy Rings Symptoms: Rings with dark green on the outside Decomposition of OM and free N
Fairy Rings Symptoms: Decline in the middle Nutrient depletion Hydrophobic soil (dry)
Fairy Rings Control: Mask with N application Aerify to improve water penetration No fungicide control
Centipede decline Favorable Conditions Late frost in spring Fluctuating winter/spring temps Excessive N, Thatch and low K
Centipede decline Symptoms Die after spring green Wilts and suddenly die
Centipede decline Control Avoid early fertilization Avoid over fertilization Apply adequate K in fall and spring
Centipede decline Control Avoid post-emergents during transition Maintain pH
Take-All Root Rot
Soil pH Some reports suggests lowering pH will help Others suggest compost topdressing Fungicides not effective
LOCALIZED DRY SPOT Sandy soils get hydrophobic Apply wetting agent
SLIME MOLD Harmless