The future of alternative strategies for snow mold control

January 11, 2023

By Paul Koch, University of Wisconsin – Madison

Snow molds are one of the most common diseases of turfgrass in temperate climates, and chemical fungicides are the primary method for controlling these damaging diseases. However, there have been some successes using ‘alternative’ strategies for snow mold control. Professor Alec Kowalewski and his team at Oregon State University have developed Microdochium patch control programs that center around repeated applications of iron sulfate, sulfur, and Civitas mineral oil. Dr. John Dempsey, a private turfgrass researcher and former golf course superintendent in Ireland, developed Microdochium patch control programs focused on repeated applications of phosphite products. Professor Tom Hsiang at the University of Guelph even developed an effective biocontrol product to control gray snow mold, though the product is no longer commercially available. Despite these reported successes, alternative strategies that provide consistent snow mold control remain elusive. Research from my own program recently found no control of snow molds in Wisconsin from repeated fall applications of iron sulfate and phosphite products (Koch and Hockemeyer, 2021; Figure 1).

Two patches in an experiment to control snow mold
Figure 1. Repeated fall applications of iron sulfate were ineffective at controlling snow mold at three locations across Wisconsin.

As part of the WinterTurf project we’re investigating a broad range of alternative products to identify potential new strategies for snow mold control. Researchers at the University of Wisconsin – Madison, Michigan State University, University of Massachusetts – Amherst, and NIBIO in Norway are testing the same set of treatments in the field across a broad range of environments to determine which, if any, products provide effective snow mold control. These treatments include commercially available biological control products, plant hormones that impact plant hardening, and plant nutrients such as sulfur and iron sulfate. The results will be collected in the spring of 2023 and successful treatments will be selected for more rigorous testing in future years.

Alternative snow mold control products were applied alongside standard chemical fungicides in Marquette, MI
Figure 2. Alternative snow mold control products were applied alongside standard chemical fungicides in Marquette, MI on October 27, 2022. The plot will be rated for snow mold severity in the spring following snow melt.

Reference

Koch, P. L., & Hockemeyer, K. (2021). Iron sulfate and phosphite products fail to suppress snow mold on amenity turfgrass in Wisconsin. Crop, Forage & Turfgrass Mgmt. 7:e20138.