Can Weeds Overtopping Soybean or Adzuki Bean Be Mechanically Pulled to Reduce Their Seed Input?

Abstract

Tall weeds escaping early weed management, such as weeds resistant to one or multiple herbicides, are an increasing concern. When weeds reach a certain size, few options other than hand weeding will limit the production and dispersal of seeds. The objective of this project was to evaluate the efficacy of the Bourquin Organic Weed Puller® (a rotating series of wheels that grab and pull) at removing tall weeds before they shed seeds in soybean and adzuki bean. Trials were set up in Canada at the Agriculture and Agri-Food Canada research farms at Saint-Jean-sur-Richelieu (SJR), QC (2 yr), and Harrow (HAR), ON (1 yr), on a loamy and a sandy soil, respectively. The experimental design included crops of different potential heights (different soybean cultivars and adzuki bean), two weed species per location (common lambsquarters [both locations] and common ragweed or redroot pigweed at HAR), and two pulling dates. The set-up also included weedy and herbicide-treated control plots. Weeds overtopping the crop canopy by at least 10 cm were tagged and characterized. Damage from the weed puller was rated as 1, pulled (desired effect); 2, cut; 3, folded; 4, stripped; and 5, intact. The seed production of damaged and intact weeds was also recorded. Less than one-third of common ragweed or redroot pigweed plants were pulled during any treatment combination. The highest pulling rates were observed for common lambsquarters at SJR (43%), but very few were pulled at HAR (3.1% max). Pulling rates were not high enough to potentially control seed inputs from herbicide-resistant populations, and successfully pulled common lambsquarters left on the ground produced thousands of viable seeds.

Evaluation of electrical and mechanical Palmer amaranth (Amaranthus palmeri) management in cucumber, peanut, and sweetpotato

“…With additional research to provide insight into the optimal applications, there is potential for the Weed Zapper and the Weedpuller to be used as alternatives to hand removal in peanut and sweetpotato. These results are contrary to those reported by Simard et al (2019), who observed suboptimal control from using the Weedpuller in soybean. The difference in results is likely due to the taller crop height of soybean compared to peanut and sweetpotato.…”

“…and adzuki bean [ Vigna angularis (Willd.) Ohwi & Ohashi] that were approximately 0.8 m at treatment, control of common ragweed ( Ambrosia artemisiifolia L.), common lambsquarters ( Chenopodium album L.), and redroot pigweed ( Amaranthus retroflexus L.) was less than 50% with three passes of the Weedpuller, and injured weeds still produced viable seeds (Simard et al 2019). However, it is possible that utilization in shorter crops could improve efficacy if weeds are treated before extensive root expansion.…”

Weed Survey of Nova Scotia Lowbush Blueberry (Vaccinium AngustifoliumAit.) Fields

“…Growers should therefore begin monitoring for this weed species and implementing control measures before plants go to seed. In addition to herbicides, non-chemical strategies such as mechanical weed pullers (Simard et al, 2019) could be investigated for management of these annual weeds in lowbush blueberry fields.…”

Evaluation of crop-topping strategies to reduce common lambsquarters (Chenopodium album) seed production in potato production systems

“…Recent work has shown varying levels of success with mechanical and chemical tactics for control of weeds overtopping a crop canopy. For example, Simard et al (2018) had limited success with mechanical control of common lambsquarters overtopping a soybean [ Glycine max (L.) Merr.] canopy with a mechanical weed puller at a targeted 10-cm weed height to use crop height differential.…”