Transcript Turfgrass Diseases

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
Take-All Root Rot
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