RESEARCH UPDATE
IMPACT OF DMI FUNGICIDES
on Creeping Bentgrass and Ultradwarf Bermudagrass During Suboptimal Growing Conditions By Aaron Tucker, Jordan Booth, Wendell Hutchens, David McCall, Ph.D.
D
emethylation inhibiting (DMI) fungicides may have phytotoxic effects on putting surfaces under periods of intense heat and stress. With newer DMI chemistries available to turf managers, this study identified impacts of both longestablished and recently-registered DMI formulations during the months of June and July on ‘G12’ ultradwarf bermudagrass (UDB) and July and August on ‘Tyee’ creeping bentgrass (CB). This research was conducted at Independence Golf Club in Richmond, VA on UDB and at Glade Road Research Center in Blacksburg, VA on CB. Fungicides of interest included Rayora (flutriafol), Banner Maxx (propiconazole), Torque (tebuconazole), Maxtima (mefentrifluconazole), and Briskway (difenoconazole + azoxystrobin) applied at the highest labeled rate. Each fungicide was applied twice at the maximum labeled rate 14 days apart
‘G12’ Ultradwarf bermudagrass at IGC 21 days after final application.
26 • MISSISSIPPI TURFGRASS • SPRING 2021
and studied with and without post-application irrigation. Data was collected every 7 days after initial application for a total of 28 days. Data collection included weekly drone images for digital image analysis, turf quality and phytotoxicity assessed visually, and clipping yields to determine treatment effects. Preliminary results indicate that post-application irrigation had little effect on plant regulation at each location. Overall, Banner Maxx with post-application irrigation resulted in the most phytotoxicity among other fungicide treatments on UDB (20%), but phytotoxicity for Banner Maxx was similar with or without postapplication irrigation. In creeping bentgrass, no phytotoxicity was measured throughout this study and clipping yields varied by date with no differences between fungicide treatments with or without post-application irrigation. •
‘Tyee’ creeping bentgrass at Glade Road Research Center 7 days after final application.
