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Evaluation of low risk weed management options in snap beans, lima beans, carrots, red beets, pea, and dry bean

Project Code: MUR06-030

Project Lead

Rob Nurse - Agriculture and Agri-Food Canada


To evaluate new, low-use rate, reduced-risk, and environmentally compatible herbicides for weed control efficacy and crop safety in snap beans, lima beans, dry beans, carrots, red beets, and peas

Summary of Results

Low-acreage vegetable crops represent a major economic component of agricultural production in Canada, and weed control remains a significant problem facing growers. To address these concerns research was undertaken between 2006 and 2007 to identify new low-use rate, reduced risk herbicides that may be suitable for registration in several minor acreage crops. As a follow-up to this project, an additional year of research on selected aspects of the study was then completed in 2008. Trials of red beet, processing pea, processing carrot, snap bean, lima bean, small red Mexican bean, and Pinto bean were assessed for a variety of products. An Environmental Impact Quotient (EIQ), the tolerance of the crop to the herbicide, the effectiveness of weed control and the final yields were all evaluated.

At the onset of the study, red beet growers were limited to only a few registered weed management treatments. Ontario sugar beet micro-rate programs already available were tested for use on red beet. They showed good tolerance on the crop and effective weed control, although the EIQ may be higher than is desirable. The sugar beet herbicides, Betamix (desmedipham/phenmedipham) and Upbeet (triflusulfuron-methyl) were also tested for use on red beet. After three years of data collection the tolerance of both products looks suitable without causing dramatic reductions in yield, with UpBeet being particularly promising. The appropriate timing of Dual II Magnum (S-metolachlor/benoxacor) was also investigated. The results suggest that all timings of Dual II Magnum should be safe for registration in red beet; however, under specific environmental conditions, application of Dual II Magnum may result in injury and some yield reduction.

The new herbicides Impact (topramezone), Kixor (saflufenacil, pending registration), and KIH-485 were tested for tolerance on processing pea. All products showed excellent crop tolerance when applied at the pre-emergence stage. Impact, however resulted in crop damage when applied at the post emergence stage.

Snap and lima bean's tolerance to several reduced risk herbicides were tested. While there were differences by bean species, there were high levels of crop damage found for most treatments. Further research needs to be undertaken to identify use patterns and rates that may be viable for the snap and lima bean market.

Processing carrot's tolerance to several herbicides at various stages was tested. Command (clomazone), when applied at either the pre-emergence or post emergence stage, Chateau (flumioxazin) and Impact all had acceptable tolerance and did not impact yield in comparison to an untreated check. The timing of Dual II Magnum application was also tested. Based on the results of one year, research showed Dual II Magnum should be applied either prior to planting or at pre-emergence for best tolerance on processing carrots.

In 2008 further trials were performed on processing carrot using Nortron (ethofumesate) and Prowl H20 (pendimethalin). Norton showed some potential as a postmergence treatment while Prowl H20 demonstrated good tolerance at two application rates. Weed control was excellent for all treatments, except for Nortron when applied alone at the post planting stage. Acceptable control was achieved when Nortron was used in a tank mix with linuron. A tank mix of either Prowl H20 or Norton resulted in the highest yields.

Herbicides applied prior to emergence or at preemergence on small red Mexican and Pinto bean demonstrated good tolerance except for KIH-485. When applied prior to planting (PPI), KIH-485 caused a high degree of damage to the beans. While the tolerance was increased when applied preemergence, yields were still reduced. In a post emergence management program using Pursuit (imazethapyr), this research showed that the addition of Basagran Forte (bentazon) was effective in reducing visual damage by up to 50% with no differences in final yield.

This project developed data which supported one registration, and three other label expansion submissions. Upbeet is now registered for use in red beets, and was also shown to have the lowest field EIQ. Dual II Magnum on carrot has been submitted for preemergence use. In addition several products were identified as candidates for further research including: Dual II Magnum for red beets and carrots and Lontrel (clopyralid) for red beets. Overall, the new herbicides tested in these trials have field EIQ's that are well below the industry standard of registered herbicides currently available. Further work is still needed; however these trials have shown that there are effective options available for weed control in low acreage crops which will help Canadian growers remain competitive while producing vegetables in an environmentally sustainable way.

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