Comparative Analyses of Glyphosate Alternative Weed Management Strategies on Plant Coverage, Soil and Soil Biota

Abstract

Glyphosate-based foliar spray herbicides are the most common method for urban weed control due to their broad-spectrum and efficacy for burndown applications. As interest in glyphosate alternatives has increased in recent years, this project assessed the efficacy of the following non-glyphosate-based alternative weed management strategies: glufosinate, imazapyr, MCPA + dicamba, prodiamine, pine oil, clove oil, nonanoic acid, acetic acid + hydrochloric acid and steam against untreated (negative) controls and glyphosate-treated sites. Across all four seasonal treatments (winter, spring, summer and autumn), glyphosate and glufosinate reduced weed coverage (>65% after 4 and 12 weeks); imazapyr reduced weed coverage by >80% after 12 weeks; and steam reduced weed coverage by >80% after 4 weeks, and after 12 weeks showed to reduce weed coverage by >20% after the second application. The MCPA + dicamba, prodiamine, pine oil, clove oil, nonanoic acid and acetic acid + hydrochloric acid treatments had mixed impacts on weed coverage. Minimal alterations to soil physicochemical properties were observed across the two sites for all treatments. Assessment of impacts the different weed management strategies had on arthropod and microbial relative abundance showed minimal alterations; with only steam observed to reduce relative microbial abundance. Glufosinate, imazapyr and steam may be considered alternatives to glyphosate for reducing weed coverage but may not be as effective or have undesirable off-target effects. Overall, glyphosate provided the most consistent weed reduction at both sites over 12 weeks, without any recorded negative off-target or soil biota impacts.

Assessing Herbicide Efficacy of Pelargonic Acid on Several Weed Species

“…In field application efficacy of pelargonic acid varied among the field trials. Overall, it was incomplete, confirming what was observed in the greenhouse experiment and what was already reported in previous field experiments conducted on spontaneous weed flora [27,29,33]. The botanical composition of weed flora can significantly affect the efficacy of pelargonic acid, and remarkable inter-specific sensitivity differences have been largely described [22,23].…”

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

“…The root fragment of the creeping perennial is called a ramet, which is genetically identical to the mother plant (Tørresen and Gerowitt, 2022), and it is often induced by mechanical soil disturbance (Håkansson, 2003). Large ramets can rapidly produce new C. arvense plants, while smaller ramets often do not survive to produce vegetative offspring due to their low carbohydrate reserves (Hamdoun, 1972). Similar to C. arvense, the emergence and number of sprouts in S. arvensis depend on the dry matter content of the roots (Lemna and Messersmith, 1990;Vanhala et al, 2006).…”

“…Moreover, the efficacy of PA as a potential herbicidal treatment was compared with that of the commonly used active ingredient glyphosate (GLY). This design facilitated a comprehensive comparison of the effects of PA treatment and two reference conditions: the untreated control (UC), representing the baseline or natural state, and GLY treatment, which serves as a standard for effective perennial weed control (Hudek et al, 2021;Kanatas et al, 2021).…”