DMI Fungicides Provide Benefits Beyond Fairy Ring Control

The most effective preventive fairy ring programs begin with a demethylation inhibitor (DMI) fungicide applied at soil temperature averaging 55-60°F at a 2" depth, followed by one or more sequential applications on 28-day intervals. Although other modes of action (MOAs) can be used, DMI fungicides provide benefits that other MOAs cannot, including:
  • Early-season knockdown of summer diseases: DMI fungicides will control all of these diseases that typically don’t appear until summer, but become active in early-spring:
  • DMIs are an important MOA for rotation:
    • Fungicides with different MOAs should be rotated when targeting specific diseases to limit the chance of resistance development
    • Some turf managers have moved away from the DMIs for various reasons, but this class of chemistry offers some of the broadest disease control we have in the turf industry
    • A general rule is to never apply more than two sequential applications of the same systemic MOA
  • DMIs and cool-season greens – Certain DMI fungicides can cause growth regulation or phytotoxicity on cool-season greens in the heat of summer.
    • Bayer DMI fungicides (Tartan® Stressgard® and Mirage® Stressgard are commonly used on cool-season greens throughout the year with no significant growth regulation or phytotoxicity (Fig. 1)
    • Using DMIs in the spring/early summer will help mitigate these concerns and subsequently target a broad-spectrum of soil-borne and foliar diseases
    • To further minimize the chance of growth regulation, do not combine DMIs with growth regulators in the same tank-mix
  • DMIs and ultra-dwarf bermudagrass greens – Growth regulation and reduced visual quality can also be a concern
    • Tartan Stressgard and Mirage Stressgard can be used on ultra-dwarf bermudagrass without adverse phytotoxic effects, unlike other DMIs. (Fig. 2)
    • Tartan Stressgard at 2.0 fl. oz. or Mirage Stressgard at 1.0 fl. oz. are recommended for use on ultra-dwarf bermudagrass greens for the prevention of fairy ring and take-all root rot
    • For fairy ring and TARR, water in immediately to the depth of fungal activity in the root zone
    • Avoid tank-mixing DMIs with wetting agents or PGRs, instead apply wetting agents and/or PGRs a minimum of 7 days before or after a DMI application
    • To limit potential stress on greens affected by winter damage and/or nematodes, delay applications of PGRs and DMIs in the spring and wait until turf recovery is complete to begin herbicide use, topdressing programs, or vertical mowing
  • For more information – See the linked Bayer Solutions Guide below for more information and contact your Bayer Area Sales Manager if you need assistance.

DMI Fungicides Bar Graph

Figure 1. Mirage Stressgard improves turf quality compared to the untreated and generic tebuconazole on creeping bentgrass/annual bluegrass plots as measured by the area under the turf quality progress curve (AUTQPC). Applications were made every 14 days from May 24 to July 18 and included Primo Maxx® at 0.125 oz./1,000 sq. ft., Mirage Stressgard at 1 oz./1,000 sq. ft., and tebuconazole at 0.6 oz./1,000 sq. ft. (equivalent AI rate as Mirage). Letters are LSD(0.05) for comparing between treatments. University of Connecticut, 2018.

DMI Fungicide Graph 2

Figure 2. The DMI fungicide Tartan Stressgard did not cause phytotoxicity on Champion or Minverde bermudagrass when applied on July 15, July 29, and Aug 12, 2017 in North Carolina. Letters are LSD (0.05) for comparing within a cultivar. North Carolina State University, 2017.

Two 28-day DMI applications starting at 2" soil temps of 55-60°F will not only control fairy ring, but will also reduce inoculum and future infections of a wide range of other diseases. Photo: Zac Reicher, Ph.D., Bayer.

  Bayer Solutions - Fairy Ring - Cool Season Turf 
  Bayer Solutions - Fairy Ring - Warm Season Turf 
  Fairy Ring on Warm-Season Turf – All States Except Florida & Texas Golf Program 2019 
  Fairy Ring on Cool-Season Turf – New York Golf Program 2019 
  Fairy Ring on Warm-Season Turf – Florida & Texas Only Golf Program 2019 
  Fairy Ring on Cool-Season Turf – Greens, Tees, & Fairways Golf Program 2019 

Primo Maxx is a registered trademark of Syngenta.
Zac Reicher

by Zac Reicher , Ph.D., Green Solutions Team Specialist

Monday, April 01, 2019

Rob Golembiewski

by Rob Golembiewski , Ph.D., Green Solutions Team Specialist

Monday, April 01, 2019