Development of improved weed management strategies for Ontario dry beans

Researching more options for weed control in Ontario beans

As our growers are aware, there is a limited number of herbicides available for weed management in dry beans. Currently, Pursuit (imazethapyr) and Permit (halosulfuron) are the only soil-applied herbicides registered for broadleaf weed control in Ontario dry beans. Although Pursuit (imazethapyr) is a very effective soil applied broadleaf herbicide, it has a narrow margin of crop safety, especially in the small seeded market classes of beans, specifically white and black beans.

This research project will develop numerous precision weed management strategies that have an adequate margin of crop safety, provide consistent broad spectrum weed control, have low environmental impact and maximize bean yield and net returns.

The project will focus on determining the following:

  • The efficacy of Treflan (trifluralin) plus halosulfuron applied alone and in combination for broad spectrum weed control in white bean in Ontario.
  • The efficacy of Dual (s-metolachlor) plus Permit (halosulfuron) applied alone and in combination for broad spectrum weed control in white bean in Ontario.
  • The efficacy of Edge (ethalfluralin) applied alone and in combination with Permit (halosulfuron), Pursuit (imazethapyr) or Authority (sulfentrazone) for broad spectrum weed control in white bean.
  • The efficacy of pethoxamid (a new Group 15 herbicide) for weed control in white bean compared to other soil applied annual grass herbicides.
  • Tolerance of dry beans to pethoxamid applied preplant incorporated and preemergence.
  • Tolerance of dry beans to group 15 herbicides including Frontier (dimethenamid-p), pethoxamid, Zidua (pyroxasulfone) and Dual (s-metolachlor) applied preplant incorporated.
  • Tolerance of dry beans to group 15 herbicides including Frontier (dimethenamid-p), pethoxamid, Zidua (pyroxasulfone) and Dual applied preemergence.
  • Tolerance of dry bean to 2,4-D applied at various preplant intervals for glyphosate resistant Canada fleabane control
  • The sensitivity of dry beans to Eragon (saflufenacil), Sencor (metribuzin), FirstRate (cloransulam), Broadstrike RC (flumetsulam) and Classic (chlorimuron) applied preplant for glyphosate resistant Canada fleabane control.

The project will also confirm the efficacy of Permit (halosulfuron) for the control of volunteer adzuki and soybean in white bean.

Tankmixes of Permit (halosulfuron) with Treflan (trifluralin), Edge (ethalfluralin) or Dual (s-metolachlor) at proper rate of application have potential to provide broad spectrum weed control in dry beans but their efficacy for weed control without injuring dry beans needs to be established under Ontario environmental conditions.

Pethoxamid is a new selective, Group 15 herbicide that inhibits seedling growth of target weeds. It is new herbicide in the chloroacetamide family which provides primarily annual grass control but also has some activity on small seeded broadleaf weeds. It provides partial control of glyphosate-resistant common ragweed and waterhemp. It can be applied preplant, preplant incorporated and pre-emergence. In the U.S. and Canada, major crops identified for its use include corn, soybean, cotton, rice and sunflower. Pethoxamid is being developed as a solo product, as well as in preformulated mixtures with other broadleaf herbicides. Pethoxamid has the potential to provide broad spectrum control of common annual grasses and small seeded broadleaf weeds in Ontario. Tolerance of dry beans to pethoxamid and its weed control efficacy in Ontario is not known and needs to be determined.

Glyphosate resistant (GR) Canada fleabane is an increasing problem in dry bean production, especially in no-till and strip-till production systems. GR Canada fleabane was first reported in Essex county, Ontario, Canada in 2010. As of 2015 there were 30 counties in Ontario with GR Canada fleabane from Essex county in the southwest to Glengarry county adjacent to the Quebec border. In addition, there are 23 counties in Ontario with multiple resistant Canada fleabane (Group 2 and 9). When it comes to managing glyphosate resistant Canada fleabane, dry bean producers need exceptional (near-perfect) weed control from prior to dry bean emergence right through the growing season.

2,4-D has been shown to provide partial control of GR Canada fleabane as a preplant burndown in soybean production, but sensitivity of dry beans to 2,4-D is not known. This research intends to determine tolerance of dry bean to 2,4-D applied at various preplant intervals for GR Canada fleabane control. This study will also determine sensitivity of dry beans to other herbicides including Eragon (saflufenacil), Sencor (metribuzin), Broadstrike RC (flumetsulam) and Classic (chlorimuron-ethyl) applied preplant for GR resistant Canada fleabane control. These herbicides alone or in a tankmix are expected to provide full season, residual weed control.

This project was funded in part through Growing Forward 2 (GF2), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of GF2 in Ontario.