Evaluating Efficacy of Oxen gold 515 EC Herbicide in Controlling Weeds in Onions.

Abstract

Onions are one of the most important vegetables in Uganda. Weeds are one of the several factors that decrease onion yield and therefore weed control is needed to increase yield. Different methods such as manual, mechanical, biological and herbicides for weed management in onion fields have been used. Herbicides offer more practical and effective means, killing up to 99% of weeds in certain situations. Many herbicides are available on market for use in onion fields by farmers but no comprehensive study has been done on newly available pendimethalin 175g/l + Oxyfluorfen 45g/l + acetochlor 300 g/l herbicide (trade name: Oxen Gold 515 EC). Therefore, in 2024/2025 an experiment was conducted in Makerere University Research Institute Kabanyolo (MUARIK) to evaluate the efficacy of this new herbicide. Randomized completely Block Design (RCBD) was used during the experiment which comprised of three replicates. The experiment consisted of test herbicide that is to say pendimethalin175g/l + Oxyfluorfen 45g/l + acetochlor 300 g/l, positive check (Oxyfluorfen 24% EC), hand weeding and zero treatment. Through analysis of variance (ANOVA), physical observations and measurements of data, results indicated that the tested herbicide was effective on both broad and grass weeds regardless of application dosage and its performance was comparable to Oxyfluorfen the positive check indicating that Oxen Gold 5151EC can be used as alternative to Oxyfluorfen for weed management in onions. Application of the pendimethalin 175g/l + Oxyfluorfen 45g/l + acetochlor 300 g/l herbicide, caused visual crop injury such as leaf tip burn, surface leaf scorching, stunting. Plant growth parameters affected significantly (p< 0.001) were plant height (cm) leaf length (cm), number of leaves. Weed parameters such as weed density, weed vigor, grass and broad-leaved weed counts were significantly reduced as well. Weeds that invaded onions during field experimental period were Ageratum conizoids (goat weed), Cyperus rotundas (Cyperus), Amaranthus spinosus (spiny pig weed), Biden pilosa (Black jack), Euphorbia hirta (milk weed), Mimosa invisa (Giant sensitive plant), Calotropis procera (swallow wort), commelina benghalensis (commelina).Since all application dosages performed similarly, recommended dose of Oxen Gold 515 EC should be used for the management of weeds in onions, as a higher dose may only add little or no benefit with unnecessary costs with high risk of increased toxicity which may lead to environmental pollution and thus ecological imbalance. Conversely, lower rates may lead to increased development of resistance in weeds due to sub lethal effects.