FIELD BINDWEED (CONVOLVULUS-ARVENSIS) CONTROL WITH FLUROXYPYR

Experiments were conducted under controlled environment and field conditions to evaluate the influence of growth stage and fluroxypyr dosage on control of field bindweed. In controlled environment studies fluroxypyr effectively controlled 8- to 12-leaf field bindweed. Shoot number, length, and dry weight, and root dry weight decreased as herbicide dose increased. The estimated ED(50) (effective dose for 50% reduction) values for shoot and root dry weight were 50 and 33 g ai/ha, respectively. The ED(50) for shoot length was 98 g ai/ha. Fluroxypyr was applied at rates from 0.2 to 0.4 kg/ha under field conditions to field bindweed at selected stages of growth. Regardless of herbicide dosage, fluroxypyr applied at the late flowering stage of growth controlled field bindweed better than when applied at the bud or early flower stage. Corn grain yield increased as a function of fluroxypyr dose in 1988 but not in 1987. Dry weight of roots and shoots of field bindweed harvested one year after treatment decreased with increasing rates of fluroxypyr. These studies demonstrate the potential of fluroxypyr for the control of field bindweed.