Dose–Response Curves of Pelargonic Acid against Summer and Winter Weeds in Central Italy

Abstract

Pelargonic acid is a non-selective post-emergence contact bio-herbicide which is registered both for cropping and non-cropping uses in several countries. Dose–response curves on the efficacy of pelargonic acid against common weeds in Mediterranean areas are not available. Dose–response curves of pelargonic acid efficacy against summer and winter annual weeds were evaluated in two field experiments (winter exp. in 2019 and summer exp. in 2020) in central Italy. Pelargonic acid was applied at five doses (1.4, 2.7, 5.4, 10.9 and 21.8 kg a.i. ha−1). Data on weed density, weed dry weight, and weed ground cover were used to calculate the efficacy of pelargonic acid against winter and summer weeds. Data were subjected to a non-linear regression analysis using the logistic dose–response model. Dose of pelargonic acid required to obtain 50%, 70%, 90% and 95% weed control against each weed species (ED50, ED70, ED90 and ED95) were estimated. ED values allowed us to classify winter and summer weeds with respect to their susceptibility to pelargonic acid (ED50 values in kg ha−1 are reported in parenthesis): Kickxia spuria (2.6) (more susceptible) > Heliotropium europaeum (3.0) > Echinochloa crus-galli (3.4) > Solanum nigrum (3.6) > Stachys annua (5.3) > Papaver rhoeas (6.5) > Veronica hederifolia (10.3) > Amaranthus retroflexus (11.4) > Matricaria chamomilla (11.6) > Portulaca oleracea (18.7) > Lolium multiflorum (> 21.8) (less susceptible). These findings will allow for the optimization of weed control by pelargonic acid and its use in weed management strategies, both in organic and sustainable cropping systems, under different environmental conditions.

Herbicidal Potential of the Natural Compounds Carvacrol, Thymol, Eugenol, p-Cymene, Citral and Pelargonic Acid in Field Conditions: Indications for Better Performance

“…This weed recovery effect could also be due to the tested volume rate. In the present research, we used 500 L ha −1 , a higher water volume rate than Panacci et al [33], who obtained a PA response curve for several weeds using 300 L ha −1 , but lower than other authors, like Webber and Shrefler [30], who applied 935 L ha −1 obtaining good weed control.…”

“…Little field research has been conducted on the efficacy of natural herbicides for weed control, as the majority have studied pelargonic acid (PA) [11,[29][30][31][32][33]. To our knowledge, there are no reports of field research on the herbicidal activity of the natural products carvacrol (CAR), thymol (THY), eugenol (EUG), p-cymene (P-CYM), and citral (CIT).…”

“…Another important factor when experimenting with new natural herbicides is the application rate. Panacci et al [33] determined the dose-response curve of PA for several broadleaf weeds using the following rate range: 1.4-21.8 kg ha −1 . They reported ED50 values for A. retroflexus, Heliotropium europaeum L., and P. oleracea, which were 11.7, 3.0, and 18.7 kg ha −1 , respectively, while our average control in terms of ground coverage at GUA and UPV was 48.0 and 81.3% at one WAT, 23.0 and 72.6% at two WAT, and 6.8 and 65.4% at four WAT using 5.7, 8.3, and 10.9 kg ha −1 of PA different formulations.…”

“…As stated previously, it is the only plant-based bioherbicide registered in the EU. The herbicidal activity of pelargonic acid has been widely studied, specially in recent years [11,12,[29][30][31][32][33][34]. Pelargonic acid can be a useful alternative to synthetic herbicides in IWM; for example, an environmentally beneficial method of managing annual weeds in soybean fields is to combine pelargonic acid herbicide with fake or stale seedbed technology to achieve a reduction of 95% compared to a normal seedbed [35].…”

The effect of two-year application of pelargonic acid on the growth of Cirsium arvense (L.) Scop. and Sonchus arvensis L

“…In light of PA's potential as a bio-herbicide and its ability to contribute to the reduction of synthetic herbicides, researchers have been exploring its efficacy, and have shown that PA is the most successful bio-herbicide available (Webber et al, 2014a;Carroll et al, 2022;Muñoz et al, 2022;Pannacci et al, 2022). However, its effectiveness varies between weed species (Webber et al, 2014a;Webber et al, 2014b).…”