Ferrous sulfate suppressed dollar spot on creeping bentgrass

Dollar spot is the most common disease of creeping bentgrass across much of the United States and requires extensive use of synthetic fungicides for adequate suppression. Alternative management strategies for dollar spot suppression are being explored by many researchers. Previous studies have shown that ferrous sulfate suppresses dollar spot at high use rates and serves as one alternative to traditional fungicides, despite some reports of injury to creeping bentgrass. It is unknown whether ferrous sulfate can be effective at lower use rates without negatively impacting canopy quality.

A new Crop Science study provides the expected suppression of dollar spot across a wide range of use rates. The researchers reported that across putting green and fairway studies, 50% of dollar spot was suppressed at a use rate of 26.4 kg ferrous sulfate heptahydrate ha^–1 with no negative impacts on overall canopy quality. Increasing the amount of ferrous sulfate beyond this had a diminishing rate of suppression. These data demonstrate a clear expectation of anticipated disease suppression based on the application rate and provide another management tool for battling dollar spot on creeping bentgrass.