Tolerance of Four Market Classes of Dry Beans to Tribenuron and Carfentrazone Applied Preplant

Limited information is available on the sensitivity of dry beans to tribenuron and carfentrazone applied preplant (PP). Four field trials were conducted at Exeter and Ridgetown, ON, Canada in 2019 and 2020 to determine the tolerance of azuki, kidney, small red and white beans to glyphosate (1800 g·ae·ha-1) + tribenuron (15 g·ai·ha-1), glyphosate (1800 g·ae·ha-1) + carfentrazone (35 g·ai·ha-1) and glyphosate (1800 g·ae·ha-1) + tribenuron (15 g·ai·ha-1) + carfentrazone (35 g·ai·ha-1) applied PP 1 - 2 days prior to seeding dry beans. Glyphosate + tribenuron, glyphosate + carfentrazone, and glyphosate + tribenuron + carfentrazone, applied PP, caused 5%, 5% and 9% bean injury at 1 WAE;7%, 6% and 10% bean injury at 2 WAE and 6%, 5% and 8% bean injury at 4 WAE, respectively. At 8 WAE, there was 0, 1% and 4% injury in azuki bean;1%, 2% and 2% injury in kidney bean;3%, 2% and 3% injury in small red bean;and 6%, 3% and 2% injury in white bean with glyphosate + tribenuron, glyphosate + carfentrazone, and glyphosate + tribenuron + carfentrazone applied PP, respectively. The injury was significantly greater with glyphosate + tribenuron in small red and white beans compared to the azuki and kidney beans. There was no difference between injury levels among market classes of dry been with glyphosate + carfentrazone or glyphosate + tribenuron + carfentrazone applied PP. There was no effect of glyphosate + tribenuron, glyphosate + carfentrazone and glyphosate + tribenuron + carfentrazone on dry bean plant stand, maturity and seed yield. However, dry bean biomass was reduced as much as 15% with glyphosate + tribenuron and 13% with glyphosate + tribenuron + carfentrazone compared to the untreated control. Dry bean height was reduced 4% with glyphosate + tribenuron + carfentrazone but was not affected with other treatments. Based on these results, there is potential for using glyphosate plus tribenuron or carfentrazone for preplant weed management in dry bean production.

Response of Four Dry Bean Market Classes to Pre-Emergence Applications of Pyroxasulfone, Sulfentrazone and Pyroxasulfone plus Sulfentrazone

Only one herbicide mode of action (ALS inhibitor) is currently available to Ontario dry bean producers for soil-applied broadleaf weed control. Four field studies were conducted over two years (2014, 2015) to examine the tolerance of four market classes of dry beans to sulfentrazone (210 and 420 g·ai·ha-1) and pyroxasulfone (100 and 200 g·ai·ha-1) applied alone and in combination. The registration of these two herbicides would provide Ontario dry bean producers with two additional modes of action for broadleaf weed control. Pyroxasulfone caused up to 23%, 6%, 7% and 10% injury in adzuki, kidney, small red Mexican and white bean, respectively;sulfentrazone caused up to 51%, 12%, 15% and 44% injury and the combination caused up to 90%, 23%, 29% and 62% injury, respectively. Kidney and small red Mexican bean density, height, seed moisture content and yield were not affected. Pyroxasulfone (200 g·ai·ha-1) + sulfentrazone (420 g·ai·ha-1) reduced adzuki and white bean density, shoot dry weight, height and yield. This study concludes that pyroxasulfone (100 g·ai·ha-1) + sulfentrazone (210 g·ai·ha-1) applied PRE can be safely used to control weeds in Ontario kidney and small red Mexican bean production.

Tolerance of Four Dry Bean Market Classes to Pre-Emergence Applications of Sulfentrazone

Ontario dry bean growers are currently limited to ALS inhibitor herbicides for soilapplied broadleaf weed control;therefore another mode of action is needed. Sulfentrazone is a PPO inhibitor herbicide that has activity on some annual grass and broadleaf weed species. Four field trials were conducted over two years (2014, 2015) to determine the tolerance of four commonly grown dry bean market classes (adzuki, kidney, small red Mexican and white bean) to PRE applications of sulfentrazone at 140, 210, 280 and 420 g·ai·ha-1. Crop injury, plant height, plant density, shoot biomass, seed moisture content and yield were examined. Sulfentrazone (420 g·ai·ha-1) caused up to 74%, 22%, 30%, and 57% injury in adzuki, kidney, small red Mexican and white bean, respectively. Plant density, height and yield were not reduced for kidney or small red Mexican bean. Sulfentrazone (420 g·ai·ha-1) reduced white bean plant density, height and yield by 28%, 29% and 29%, respectively;and reduced adzuki bean plant density, height and yield by 51%, 34% and 57%, respectively. Overall, kidney and small red Mexican bean were the most tolerant to sulfentrazone, followed by white bean, and then adzuki. This study determined sulfentrazone applied PRE is safe for Ontario kidney bean and small red Mexican bean crops.