Weed Control in Dry Beans
April 18, 2005
Conduct research that will help answer dry bean growers question pertaining to weed control and herbicide use issues and problems.
1. Evaluate weed control and dry bean tolerance to Sandea (halosulfuron).
2. Evaluate dry bean tolerance to Spartan (sulfentrazone).
3. Evaluate adjuvant enhancement of Valor (flumioxazin) for dry bean desiccation.
Benefits to ND/MN dry bean growers
Sandea will register on dry bean soon. A data base of weed control and dry bean safety will help growers determine if this tool can be used in their weed control efforts.
There is concern that Spartan may injure dry beans in certain soil conditions, like high pH. Subjecting several dry bean types to varying rates of Spartan in high pH soils across the state will help determine the risk of injury.
Valor will be registered as dry bean desiccant within a couple of years. Valor responds to adjuvants. Adjuvant research will help determine those products that will enhance Valor the greatest.
Results - Sandea effectiveness
Sandea is a preemergence and postemergence herbicide that controls many large-seeded broadleaf weeds, like wild mustard, common cocklebur, common ragweed, and marshelder, but is weak on redroot pigweed, common lambquarters. Applying Sandea with a soil applied grass herbicide like Outlook, Dual Magnum or with Spartan can provide near complete broadleaf weed control. Sandea has no grass activity.
Dry bean tolerance to Spartan
Experiments were conducted to evaluate the tolerance of six dry bean types to Spartan. "T-39" Black bean, "IU465" Great Northern bean, "Vista" Navy bean, "312" Pink bean, "Maverick" Pinto bean, and "Garnett" Small Red bean were seeded in 2004 to soils with a pH between 7.8 to 8.3, and organic matter between 2.5 and 5.5%.
Sandea is a preemergence and postemergence herbicide that controls many large-seeded broadleaf weeds...but is weak on redroot pigweed, common lambquarters.
Spartan was applied at rates from 2 to 8 oz/A immediately after seeding. At Buffalo, Thompson, and Oakes, N.D., none of the bean types exhibited significant injury symptoms from rates of 4 oz/A or less. Treatment rates from 5.33 oz/A and 8 oz/A treatments caused slight to moderate injury symptoms early in the growing season, but symptoms declined as the season progressed. Primary injury symptoms included stunted growth, wrinkling of leaf tissue, necrotic leaf spotting, chlorosis, and veinal discoloration. In this experiment, injury appeared to be correlated most strongly to Spartan rate than any other factor. Injury increased as Spartan rate increased.
Spartan injury appears to be more strongly correlated to soil pH than any other factor. Spartan injury was more severe in high pH plots than low pH plots.
At Minot, visible injury symptoms were most observed on Black and Navy. Primary injury symptoms included stunted growth, slow emergence, leaf wrinkling, chlorosis, and necrotic leaf spotting. Spartan injury was most severe in the Navy bean type, as significant injury occurred at all treatment rates. Order of susceptibility from most to least tolerant is Navy bean, Pink, Black, Small Red, Pinto, and Great Northern. Spartan injury appears to be more strongly correlated to soil pH than any other factor. Spartan injury was more severe in high pH plots than low pH plots. Spartan injury increased as soil pH increased because the Spartan was more soluble in the soil solution. Additionally, Spartan injury decreased as soil organic matter increased because the herbicide was adsorbed to the organic matter.
Valor has shown activity as a dry bean desiccant and enhancement from primarily oil based adjuvants. Methylated seed oil (MSO) and MSO & Basic Blend (BB) adjuvants with Valor gave the greatest and most rapid dry bean desiccation. Superb HC (high emulsifier concentration petroleum oil), which is used at half the rate of most petroleum oil adjuvants plus InterLock (deposition aid + drift retardant), also gave high and rapid bean desiccation. Organosilicone surfactants that reduce surface tension of spray droplets to increase canopy penetration did not improve desiccation. These data support previous research, which indicated oil adjuvants improve dry bean desiccation with Valor.
3 days after treatment