Impact of electrocution on weed control and weed seed viability in soybean
Abstract
Field experiments were conducted in 2020 and 2021 to test the effectiveness of electrocution on several weeds commonly encountered in Missouri soybean production using an implement known as The Weed Zapper[trademark]. The first set of experiments targeted individual weed species. Weeds examined were waterhemp, cocklebur, giant and common ragweed, horseweed, giant and yellow foxtail, and barnyardgrass. Each species was electrocuted when plants reached average heights and/or growth stages of 30 cm, 60 cm, flowering, pollination, and seed set. Each electrocution treatment took place either once or sequentially, and at two different tractor speeds. Growth stage at the time of electrocution had a significant effect on weed control, with greater control achieved when electrocution occurred at later 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 percent among the species evaluated. A separate experiment was conducted to determine the effects of electrocution on waterhemp escapes in soybean, and to determine potential soybean injury and yield loss. Electrocution timings took place throughout reproductive soybean growth stages. 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 percent 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.
Degree
M.S.