TechNotes August 5 – Dollar Spot, Soil Temps

Dollar Spot Becoming More Active. With the expected drop in high temperatures this weekend, the likelihood of dollar spot becoming active increases.  Dollar spot persists and can become a serious problem on annual bluegrass, and creeping bentgrass turf through the fall.  The pathogen, Sclerotinia homoeocarpa, actively grows and infects when temperatures are between 60 and 86 degrees Fahrenheit.  White mycelium is often present in the mornings when dew is present.  With morning fog becoming more frequent, this will only increase the severity and activity of dollar spot.
 
Cultural practices for reducing the conditions favorable for this disease include reducing the leaf wetting period.  Prolonged periods of wetness when temperatures are favorable are conducive for disease symptoms.  Practices to reduce the wetting period include dew removal through a light morning syringe or whipping or dragging the turf.  In addition, irrigate when the likelihood of prolonged wetting is reduced.  Fall fertilization should help reduce the severity of dollar spot.

SOIL TEMPERATURES.