Attempted Safening of Topramezone on Bermudagrass.

Field trials were conducted in the summer of 2015 and 2016 to determine whether various additives may help safen topramezone (Pylex, BASF, Research Triangle Park, NC) use on bermudagrass.  Mixtures of topramezone (12.3 g ai/ha) and MSO (0.5% v/v) were applied in combination with 5 different additives including triclopyr (35 g ai/ha), green turf pigment (1.75 kg ai/ha, Sarge 2.0, Numerator Technologies Inc., Sarasota, FL), green turf paint (8.3% v/v, Lesco Green Turf Paint, Site One Landscape Supply, Roswell, GA), ammonium sulfate (353 g ai/ha), and chelated iron (1.22 kg ai/ha, Sprint 330, BASF, Research Triangle Park, NC). Previous research using triclopyr has shown safening of topramezone, but our results showed similar bleaching symptoms and injury to the other treatments. Preliminary results showed that chelated iron significantly reduced bleaching symptoms associated with topramezone injury. At 5 days after treatment (DAT), topramezone plus chelated iron injured bermudagrass <20%, as compared to ~60% for topramezone alone. By 11 DAT, chelated iron and topramezone treatments showed <5% bleaching as compared to the other treatments which showed a bleaching range between 70-90%.  By 20 DAT, all bermudagrass plots had recovered and showed no signs of residual bleaching. Although the bermudagrass fully recovered for all treatments by 20 DAT, all of the treatments except for the combination of chelated iron and topramezone showed unacceptable levels of bleaching injury. This data suggests that the addition of chelated iron to the mixture of topramezone and MSO may act as a safener on bermudagrass.