Causal Agent:
Clarireedia jacksonii
Clarireedia monteithiana
Clarireedia bennettii
Clarireedia homoeocarpa
Susceptible Turfgrasses:
Dollar spot affects all turfgrass species, including both cool-season and warm-season varieties.
Identification:
Dollar spot manifests as white or tan spots of varying sizes on turfgrass. Key identifying characteristics include:
Hourglass-shaped leaf spot lesions with a distinctive dark-brown or purple border.
The presence of white, fluffy mycelium (fungal threads) visible in the early morning, especially when heavy dew is present.
These spots can coalesce to form larger, irregular patches if conditions persist.
Favorable Conditions:
Dollar spot can occur anytime from mid-spring to late fall. It is most active under the following conditions:
Temperature Range:
Night temperatures between 55°F to 75°F (13°C to 24°C).
Weather:
Warm days and cool nights.
Presence of heavy dews or prolonged leaf wetness.
Additional Risk Factors:
Poorly Nourished Turf: Insufficient nitrogen can make turf more vulnerable to infection.
Dry Soil Conditions: While the foliage may be wet, dry soil conditions can enhance disease severity.
Cooler Periods: In some regions, dollar spot can persist or recur even during mild winter periods.
Management Tips:
Proper Fertilization
Maintain balanced nitrogen levels to promote healthy turf growth.
Irrigation Practices
Water deeply and early in the morning to reduce prolonged leaf wetness.
Avoid drought stress and irrigate turf frequently enough to maintain good soil moisture when the disease is active.
Mowing Practices
Avoid mowing wet grass to minimize spreading the disease.
Thatch Control
Aerate and dethatch as needed to improve air circulation and reduce moisture retention.
After disease subsides
Apply modest amounts of nitrogen (~ 0.25 lbs N/1,000 ft2) to enhance recovery to higher maintained turf; spoon-feeding (i.e., ~ 0.15 lbs N/1,000 ft2) greens, collars and approaches every 10-14 days is powerful in promoting recovery.
Rolling, mowing in the morning, and dew removal
Helps reduce disease severity on greens and elsewhere.
