The potential for dollar spot severity increases with the relatively warm humid weather present through much of the northern and eastern United States. In the Midwest dollar spot became more apparent late last week.  The increased wetness along with a rise in temperature (even though some places had well below normal temperatures) was enough to activate the disease.  Dollar spot was active on the usual turfgrasses - annual bluegrass, and creeping bentgrass – but it is also active on Kentucky bluegrass.     The pathogen, Sclerotinia homoeocarpa, actively grows and infects when temperatures are between 60 and 86 F.  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.