Efficacy of pelargonic acid on non-cropped lands

This study presents the results of a two-year field experiment (2022 and 2023) conducted on non-cropped lands in Leningrad region near of All-Russian Research Institute of Plant Protection. The aim of the study was to evaluate the biological effectiveness of pelargonic acid on non-cropped lands. The experimental setup included an untreated control and four different application rates (0.3; 0.5; 0.7 and 1.0 l/100 m2) of pelargonic acid. The experiments were carried out in randomized block design with four replications in accordance with the guidelines for testing herbicides. Net plot size was 25 m2. During the experiments, annual and perennial dicotyledonous, as well as annual cereal weed species, were found on the experimental plots. The total number of weeds in the experimental plots exceeded 250 plants/m2. It was revealed that a few hours after treatments, such weeds as Echinochloa crusgalli, Fallopia convolvulus, Polygonum lapathifolium, Chenopodium album, Spergula arvensis and Sonchus arvensis regardless of their stage of development turned brown and withered. Sinapis arvensis and Erodium cicutarium were less sensitive to treatments with 0.3 and 0.5 l/100 m2 of pelargonic acid. The pelargonic acid caused only temporary control against weeds. In the present study, the weeds recovered about 15 days after treatment: new shoots of Echinochloa crusgalli began to appear on all plots treated with pelargonic acid and did not differ compared to the untreated control. By the 30 days after treatment, the shoots of annual dicotyledonous weeds began to appear on plots treated with 0.3 l/100 m2 of pelargonic acid. The data obtained from experiments indicate that the use of pelargonic acid as a herbicide can be considered as a component of an integrated weed management strategy. Its use as a stand-alone tactic seems most appropriate on non-cropped lands, in cases where rapid weed control is required, and the duration of the protective effect is a less important factor.