Formulation, Rate and Season and Application Effects of Hexazinone (Velpar) Gridball on Oak Topkill
Hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-l,3,5-triazine-2,4(1H,2H)-dione] gridball was tested for site preparation on a loamy sand soil. The gridball was applied in the 1 and 2 cc formulations at 0.56, 0.84 and 1.12 kg ai/ha in a completel~y randomized design with three replications in April, June, and August 1978. After two growing seasons the 1 cc gridball had a slight performance advantage over the 2 cc gridball for the April application, but overall oak (Quercus sp.) topkill from the 1 cc gridball was not significantly different from topkill caused by the 2 cc gridball. Only the highest rate applied approached the minimum acceptable topkill level of 80%. The April and June applications gave similar results, and both were better than the August application. The Alabama 24-C label probably needs to be changed to allow higher application rates for site preparation on loamy sand soils.