One of our regular Golfdom emails, "Putting down roots," just went out. Karl Danneberger, Ph.D., wrote this one about dollar spot.
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Dollar spot is the most prevalent disease on high quality turf in the northern temperate region of the United States. Dollar spot is most active within the temperature range of 59 to 86 degrees F with high humidity and leaf wetness. In general, warm humid days, cool nights and heavy dews are quite favorable for disease development. Although canopy moisture needs to be present, dollar spot is more severe on dry soils. Given the wide environmental conditions which dollar spot can occur makes it the centerpiece of any disease control program.
During winter the dollar spot fungus overwinters as dormant mycelium or sclerotial flakes. The amount present during the winter influences the arrival and severity of the disease in spring or summer. Researchers at several universities have reported that a fungicide treatment in early spring can delay the onset of dollar spot much later into the year. An application at approximately the second true mowing of the season (not counting removal of winter growth) has been effective in delaying the initiation and severity of dollar spot during the growing season. If dollar spot is a chronic problem, it may be worth experimenting with an early application.
-- Karl Danneberger, Ph.D.