turfgrass diseases. turfgrass disease disease: normal development disturbed; reduces value
TRANSCRIPT
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 CONTROLProper turfgrass establishment• At least 6” of topsoil• Properly graded with good drainage
CULTURAL CONTROLMowing• Mow within correct height• Good cut
CULTURAL CONTROLIrrigation• Avoid irrigating in the evening• Early morning to knock off the dew• Deeply and infrequently
CULTURAL CONTROLNutritional status• Influences diseases• Excessive N favors Pythium and Brown Patch
CULTURAL CONTROLNutritional status• Deficient N favors Dollar Spot and Rust
CULTURAL CONTROLNutritional status• Potassium helps environmental stress• Use K in a the same proportions as N
CULTURAL CONTROLThatch 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
FUNGICIDEContacts: form preventative coating
FUNGICIDEContacts• New leaves have no protection• Fungicide degrades under irrigation,
sunlight, mowing• Effective for 7 to 14 days
FUNGICIDEContacts• Broad spectrum controls mostly foliar
diseases and not root/crown diseases
FUNGICIDEPenetrant• Protective and curative• Effective for 15 to 30 days
FUNGICIDEPenetrant• Specific MOA, develops resistant strains• Some chemicals are mixes to take advantage of both the
contact and systemic effects
Brown PatchCausal Agent: Rhizoctonia
Brown PatchHosts: zoysia, St. Augustine, centipede
Brown PatchFavorable Conditions: • Spring and fall months• Start watching in August
Brown PatchSymptoms:• Smoke ring on greens• No leaf spots, leaf sheath rot at base
Brown PatchSymptoms:• Shoots pull off from stolons easily• Roots not affected
Brown PatchControls:• 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 SpotControl:• Collect clippings• Raise mowing height
Dollar Spot
Host: bermuda, zoysia
Dollar Spot
Favorable Conditions: • Warm weather, 60 to 80 F• Low N• Thatch
Dollar SpotSymptoms:• Leaf lesions band across leaf with purple border
Dollar SpotSymptoms:• White patches in dew• fungus
Dollar SpotControl:• Apply N
Dollar SpotControl:• Apply N
Fairy Rings
Causal Agent: fungi
Fairy Rings
Favorable Conditions:• Soils with high OM• Frequently old tree stumps
Fairy RingsSymptoms:• Rings with dark green on the outside • Decomposition of OM and free N
Fairy RingsSymptoms:Decline in the middle• Nutrient depletion• Hydrophobic soil (dry)
Fairy RingsControl:• 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 declineSymptoms • Die after spring green• Wilts and suddenly die
Centipede declineControl • Avoid early fertilization• Avoid over fertilization• Apply adequate K in fall and spring
Centipede declineControl • 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