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 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