Make dollar spot pay

Dollar spot - often occurring as clusters of small, round, tan-colored blemishes - is a common concern across the golf industry, so research is plentiful and ongoing. In fact, Todd Hicks, program coordinator with The Ohio State University Turfgrass Pathology Program in the Department of Plant Pathology, said they’ve made it their main research focus for about the last 12 years.

According to Hicks, dollar spot can affect most grass species and is a major concern for turf managers in the Midwest and Northeast.

“The disease can be brought on in the spring and fall by night time temps around 60-65 F and day time temps of 75-85 F,” he said. “High relative humidity mornings (70-80 percent) and heavy dew provide the right environment for infection.

“Stressed turf that is managed under poor fertility can also lead to dollar spot outbreaks. Slow-growing turf from other environmental and management practices, such as heavy use of plant growth regulators, can increase severity.”

Dollar spot is easy to identify on turf, giving superintendents the best chance at fighting the disease.

“Dollar spot on greens can range in size from small flecks to silver-dollar-sized areas that, under severe conditions, will grow together to form larger patches,” Hicks said. “On fairways or high-cut turf, the individual spots may be larger - 1-2 inches in diameter.”

Research shows the best way to fight this disease is to have a sound fungicide program that targets dollar spot in the spring and again in the fall, according to Hicks. Make sure to cover all bases culturally, also, like adequate fertility and knocking off morning dew. 

“We are firm believers of the early spring spray program,” Hicks said. “This is putting out an early application for the disease long before it shows up. In theory, this pushes the inoculum level down when it’s weak, causing the disease to show up later and in a weaker state. This puts the turf manager ahead of the disease and if a breakthrough happens, the disease pressure is kept low and manageable.”

Winning the war against dollar spot takes diligence, and careful application of fungicide, said Hicks.

“When the weather and time of year are just right for that heavy breakout of disease, take a look at your fungicide labels,” he said. “This is not the time to be stretching out dates for your fungicide coverage on dollar spot. In fact, most of the time fungicides need to have their windows of application shortened to provide adequate protection. Also, use the high-labeled rate of fungicide to maximize management of this disease.”