Posted by Lane Tredway at 2:00 PM Tuesday, October 27, 2009 Labels: aerification , bermudagrass , DMI , phytotoxicity , putting greens , Southeast
Those of you that follow this blog know that I am not a big fan of using DMI fungicides on creeping bentgrass and annual bluegrass putting greens during the heat of summer. The impacts of these fungicides on bermudagrass greens, however, are not as well understood. Some of the newer DMIs, like Trinity, Triton and Tourney, are not labeled for application to ultradwarf bermudagrass varieties. Even though these products are safer on the cool-season grasses, they can cause severe phytotoxicity and thinning of 'Champion', 'Tifeagle' and 'Miniverde' greens.
A recent trial we performed on 'Champion' bermudagrass in Rocky Mount, NC showed some unexpected results. Each fungicide was applied once, on August 20, the day after the greens were hollow-tine aerified and topdressed. The plots were evaluated for phytotoxicity, turf quality, and recovery from aerification on September 1.
Not surprisingly, plots treated with Trinity, Tourney, and Triton FLO exhibited significant phytotoxicity and reduced turf quality as compared to the untreated control. Banner and Bayleton had similar effects, just not as severe as the others.
What was unexpected was the effect of the DMIs on recovery from aerification, as measured by the number of aerification holes still visible on Sept 1. Plots treated with Trinity, Tourney, and Triton FLO recovered almost as quickly as the untreated plots, whereas both Bayleton and Banner dramatically slowed recovery, especially Banner.
So, the take home message is, even though Bayleton and Banner are labeled for application to bermudagrass greens, these products can have adverse affects on the turf, in this case, slower recovery from aerification. More research is needed to fully characterize the effects of the DMIs on bermudagrass greens. In the meantime, I'd recommend avoiding applications of DMI fungicides either before or after hollow-tine aerification practices.