Fall Turfgrass Diseases

Stem Rust

Because weather conditions often change quickly in the fall, an outbreak of turf disease can erupt suddenly. Turf experts advise that in the fall, maintenance professionals should check for disease outbreaks more frequently.

Common Fall Diseases

Stem Rust
Symptoms:
- Leaves appear yellow or orange - ''rust infected.''
- Spread by clouds of orange rust spores when leaves are disturbed.
- Orange or brick-red pustules grow on leaves, rub off easily.
Treatment
- Regular mowing and removal of grass clippings is helpful.
- Heavy infections may require fungicides
- Useful treatments include: azoxystrobin, chlorothalonil, fluoxyastrobin, mancozeb, propiconazole, thiophanate-methyl, triadimefon or trifloxystrobin.

Leaf Spot/Melting Out

Leaf Spot/Melting Out
Symptoms:
- Small, purplish to black oval spots on leaf blades.
- Spots increase, with beige-colored centers and brown or purple margins.
- Disease ''melts out'' into the sheaths and crowns of the plant.
- Affected turf looks light brown and thinned from a distance.
- Typically a springtime disease.
- Fall reoccurrence possible after several weeks of cool and moist conditions.
Treatment:
- Incorporate disease-resistant cultivars into the turf through re-seeding or re-sodding.
- Moderate fertility levels and early morning watering are helpful as well.
- For severe symptoms, apply azoxystrobin, chlorothalonil, fludioxonil, fluoxastrobin, iprodione, mancozeb, propiconazole, thiophanate-methyl, tritfloxystrobin or vinclozolin.

Red Thread

Red Thread
Symptoms:
- Survives as sclerotia and dormant mycelium in turf plants
- Often spread by mowing equipment, especially during damp weather
- Appears as patches with a pinkish to tan cast.
- Infected blades die from the tip downward, affecting leaves and leaf sheaths.
- Leaves become covered with pink gelatinous strands of mycelium that can stick together in moist autumn seasons.
- After its disease activity ceases in the summer, it may resume in the fall.
Treatment:
- Remove clippings
- Providing a balanced fertility application help prevent severe infection.
- On turf with a history of red thread, begin a preventative fungicide program when temperatures reach upper 60s and 70s, especially if infection occurred in the spring.
- Apply products that include azoxystrobin, chlorothalonil, fenarimol, flutolanil, iprodione, mancozeb, myclobutanil, polyoxin, propiconazole, pyraclostrobin, triadimefon, triticonazole or vinclozolin.

Stripe Smut

Stripe Smut
Symptoms:
- Infected plants take on a yellowed appearance.
- Usually occurs in 6- to 12-inch circular patches, and can form larger areas.
- Leaves on infected plants show yellow stripes that later turn gray and black.
- Eventually, the leaves shred and curl.
- Like red thread, stripe smut can resume growth in the fall.
Treatments:
- Applications of fungicides like fenarimol, propiconazole or triadimefon should be applied prior to the onset of symptoms for best results.

Powdery Mildew

Powdery Mildew
Symptoms:
- Powdery mildew appears in the turf as if it was dusted with flour.
- Typically develops in shady areas and/or where air movement is insufficient.
- Affected leaves turn from white to yellow and eventually die.
- Causes a thinning of the stand
Treatments:
- Improve sunlight penetration and increase airflow across grass.
- Fungicides such as myclobutanil, propiconazole or triadimefon provide effective control.???(R)???AE'?N????e'?N,A+