A number of new experimental herbicides in the category of the diphenyl ether chemistry have shown to be selective to cotton (Gossypium hirsutum L.) and to control many grass weeds including common bermudagrass [Cynodon dactylon (L.) Pers.]. Preliminary studies at separate field locations within Mississippi have shown variable results with these herbicides. Previous studies with bermudagrass, johnsongrass [Sorghum halapense (L.) Pers.), purple nutsedge (Cyperus rotundus) and other weed species have shown that biotypes of the same species will often respond differently to the same herbicide. This study was conducted on seventeen different bermudagrass biotypes obtained from fields in Mississippi, Tennessee, Arkansas, and Louisiana to determine the extent of variability among selected biotypes to diphenyl ether and other types of herbicides.

Nine biotypes were collected from cotton fields in different counties in Mississippi. Eight biotypes were collected from federal and state forestry nurseries in Mississippi, Tennessee, Arkansas, and Louisiana. Each biotype was grown in the greenhouse during the winter and planted in the field on May 3, 1982. Herbicides were applied over-the-top with either conventional or logarithmic spray equipment on June 11, 1982.