Effect of integrated weed management on yield and economics of irrigated groundnut

Abstract:

Producing a profitable irrigated groundnut crop in southern Australia means keeping weed pressure below the economic threshold during the first 40 days after sowing, when the slow-establishing peanut canopy leaves the inter-row space open to aggressive invaders. This research compared seven weed management strategies ranging from unweeded controls to an Integrated Weed Management (IWM) package combining pre-emergence herbicide, inter-row cultivation, and one hand weeding in a randomised complete block design with four replications at the Barossa Institute research farm, Adelaide, South Australia, during the 2022-23 and 2023-24 summer seasons. Weed density, weed dry matter, pod yield, haulm yield, harvest index, and economic returns were recorded. The IWM package produced the highest mean pod yield (2.84 t/ha), 163% above the weedy check (1.08 t/ha) and 17.4% above the best single-method treatment (hand weeding twice, 2.42 t/ha). Weed control efficiency reached 91.3% under IWM compared with 64.7% for pendimethalin alone. The benefit-cost ratio of IWM (2.12) exceeded all other treatments. Cyperus rotundus and Echinochloa colona together accounted for 54.2% of the weed flora. Results confirm that combining chemical, mechanical, and manual methods delivers both agronomic and economic superiority over any single-method approach under irrigated conditions.