The impact of electrocution treatments on weed control and weed seed viability in soybean

Abstract

Field experiments were conducted in 2020 and 2021 to determine the effectiveness of electrocution on several weeds commonly encountered in Missouri soybean production using an implement known as The Weed Zapper™. In the first study, the effectiveness of electrocution on waterhemp, cocklebur, giant and common ragweed, horseweed, giant and yellow foxtail, and barnyardgrass was determined. Electrocution was applied when plants reached average heights and/or growth stages of 30 cm, 60 cm, flowering, pollination, and seed set. Electrocution was applied once or twice, at two different tractor speeds. Electrocution was more effective at the later plant growth stages. Pearson correlation coefficients indicated that control of weed species was most related to plant height and amount of plant moisture at the time of electrocution. When plants contained seed at the time of electrocution, viability was reduced from 54 to 80% among the species evaluated. A second study determined the effect of electrocution on late-season waterhemp plants, and also soybean injury and yield. Electrocution timings took place throughout reproductive soybean growth stages. The control of waterhemp escapes within the soybean trial ranged from 51 to 97%. Yield of soybean electrocuted at the R4 and R6 growth stages were similar to the non-treated control, but soybean yield was reduced by 11 to 26% following electrocution at all other timings. However, the visual injury and yield loss observed in these experiments likely represents a worst-case scenario as growers that have a clear height differential between waterhemp and the soybean canopy would not need to maintain contact with the soybean canopy. Overall, results from these experiments indicate that electrocution as part of an integrated program could eliminate late-season herbicide-resistant weed escapes in soybean, and reduce the number and viability of weed seed that return to the soil seedbank.

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

“…Once the weeds became larger, the electrical applications were less effective because of the increased weed biomass that needed to be treated. This is contrary to previous research, which reported electrocution to be more effective at later plant growth stages (Schreier et al 2022).…”

“…Thus four weekly and two treatments, spaced 2 wk apart, were required for the 0.3- and 0.6-m application height, respectively, though only one treatment was required for the 0.9- and 1.2-m application heights. Schreier et al (2022) also observed increased weed control from multiple passes with the Weed Zapper. Hand weed removal consistently resulted in optimal weed control.…”

“…However, after treatment, plants primarily died and ceased maturation, reducing seed production at 4 WAI by 93% and 70% when treated 0 and 2 WAI, respectively. Similarly, Schreier et al (2022) reported weed seed viability reductions from 54% to 80%. Treatments did not have a negative effect on germination or seedling length, indicating that the quality of seeds was unchanged by electrical treatment in the present study based on the variables that were recorded.…”

Exploring the potential of electric weed control: a review

“…In Europe, the application of electric weed control with the Zasso ™ XPower with XPU applicator (continuous plant-electrode contact) at 3 km h −1 controlled 90% of A. artemisiifolia per year; the pollen from this plant is a common allergen in Europe, where an estimated 33 million people suffer from pollen allergies (Lake et al 2017;Trognitz et al 2020). In a separate study, Schreier et al (2022) found that electric weed control reduced weed seed viability by 54% to 80% in E. crus-galli, X. strumarium, A. artemisiifolia, S. faberi, A. trifida, S. pumila, and A. tuberculatus with the Weed Zapper ™ 6R30 (spark-discharge), as previously discussed. In this way, electric weed control can help reduce not only allergy symptoms but also agricultural weed seedbanks.…”

“…The booms also fold for transportation (Ruen 2018). The efficacy of the Weed Zapper ™ 6R30 unit was recently studied in a soybean crop by Schreier et al (2022), as previously discussed.…”