When it comes to preventing turfgrass diseases, the earlier fungicide is applied, the better. A demethylation inhibitor (DMI) fungicide is the best first step in disease control and management this spring.

But what is a DMI fungicide—and what does it do? DMI fungicides differ from “regular” fungicides in the sense that they target ergosterol, an integral part of many fungi plasma membranes and necessary for growth. By inhibiting this key puzzle piece from biosynthesizing, fungi simply won’t grow.

Benefits of DMI Fungicides

We mentioned that earlier is better, and DMIs provide early season control. They’re an effective provider of early knockdown of summer diseases when applied at soil temperatures from 55-65°F at two inches. On Kentucky bluegrass and creeping bentgrass greens, DMIs control fairy ring, dollar spot, brown ring patch, anthracnose, summer patch, and take-all patch.

Choosing a Fungicide for Greens

A superintendent’s choice will be dependent on their specific type(s) of turfgrass and disease concerns. Fungicides like Densicor, Maxtima, and Rayora are commonly used and recommended. Most DMIs should be applied monthly, so be sure to stock up for season-long control.

Importance of DMIs in Rotation

Resistance management is an important part of any fungicide program. DMI fungicides are Group 3 fungicides, so it’s important to rotate to a different group/mode of action after using a DMI in order to prevent resistance. While some superintendents have moved away from DMIs, they offer broad disease control and shouldn’t be overlooked.

Alleviating Concerns Regarding DMIs and Cool-Season Greens

A common reason superintendents shy away from DMIs is that certain products can cause phytotoxicity and growth regulation issues in the heat of summer. Third-generation DMIs like Densicor by Envu, Maxtima by BASF, and Rayora by FMC, however, show excellent safety results on cool-season turf when applied alone or with growth regulators. Any newer product should not cause issues.

Next Steps

We’ve covered why DMI fungicides are a key part of effective disease management and how using DMIs in the spring and early summer helps cool-season greens thwart diseases. If you have any additional questions about DMI fungicides and how they can help your course keep diseases away, contact your ATS rep with no obligation. We’re here to share our knowledge. Don’t have a rep yet? Fill out a quick form to get connected.