Weed management in cranberry bean with linuron

Field studies were conducted at the Huron Research Station near Exeter, Ontario, in 2006 to 2009 to determine if the sequential application of trifluralin plus imazethapyr applied preplant incorporated (PPI) followed by linuron applied pre-emergence (PRE) at various doses can be used as an effective weed management strategy in cranberry bean production. There was minimal crop injury (6% or less) with various herbicides evaluated at 1 and 4 wk after emergence (WAE). Trifluralin plus imazethapyr applied PPI provided 97 to 100% control of common lambsquarters, 100% control of redroot pigweed, 99 to 100% control of wild mustard, 93 to 100% control of common ragweed, and 97 to 100% control of green foxtail. Linuron applied PRE provided 11 to 100% control of common lambsquarters, 90 to 100% control of redroot pigweed, 78 to 100% control of wild mustard, 71 to 100% control of common ragweed, and 20 to 100% control of green foxtail. The sequential application of trifluralin plus imazethapyr applied PPI followed by linuron applied PRE at various doses provided 100% control of common lambsquarters, 100% control of redroot pigweed, 100% control of wild mustard, 96 to 100% control of common ragweed, and 97 to 100% control of green foxtail. Weed density and shoot dry weight correlated well with the level of weed control. All of the herbicide treatments evaluated increased cranberry bean yield compared with the weedy control. Based on these results the sequential application of imazethapyr plus trifluralin applied PPI followed by linuron applied PRE at 1000 and 2500 g a.i. ha-1 provides a safe and efficacious weed management strategy in cranberry bean production.