Sixteen applications of imazapyr and other herbicides were made to field bindweed from 1982 to 1986. Control with imazapyr was 89% or more 1 yr after treatment at 0.14 kg ai ha-1 when plants were growing vigorously at application. Only 1 of 16 applications of imazapyr at 0.56 kg ha-1 controlled less than 90% regardless of plant vigor. Control at 0.56 kg ha-1 was usually superior to that obtained with dicamba at 1.1 and 2.2 kg ae ha-1, and 2,4-D at 1.1 kg ae ha-1, as well as combinations of picloram with either 2,4-D or dicamba. All herbicides were less effective when applied to field bindweed with poor vigor. Winter wheat planted in the fall up to 122 days after application was injured 20 to 88% by imazapyr at 0.14 kg ha-1. Sorghum planted the next spring was injured 15% or less by imazapyr at 0.14 and 0.28 kg ha-1.

Greenhouse experiments were conducted to determine effects of watering frequency, drought stress, and a combination of watering frequency and glyphosate on growth of field bindweed. Watering daily, twice weekly, or weekly to field capacity affected field bindweed grown from seed differently than plants grown from root runner segments. Shoot and root dry matter of plants grown from seed increased when plants were watered frequently but dry matter allocated to root runners did not change when plants were watered less frequently. Plants grown from root runner segments increased their shoot and root runner dry matter when watered frequently, but root dry matter was not affected by watering frequency. Plants grown from seed had highest regrowth when watered weekly and plants grown from root runner segments had higher regrowth when watered daily. Drought reduced survival rate and dry matter of surviving plants. Frequency of watering and whether plants began from seeds or root runner segments influenced glyphosate action on field bindweed. No regrowth was observed 6 months after 1.5 kg ai/ha of glyphosate was applied to plants that had been grown for 8 weeks under three different watering frequencies.