Evaluation of critical weed-free period for three sweetpotato (Ipomoea batatas) cultivars

Sweetpotato [Ipomoea batatas (L.) Lam.] is a staple crop that provides nutritional benefits to humans globally, but it is subject to yield loss when competing with weeds, especially during the early stage of establishment. Yield loss can vary widely based on the cultivar, production environment, weed species, and management techniques. To address this challenge, we conducted field research at the Samuel G. Meigs Horticulture Research Farm, Lafayette, IN, and at the Southwest Purdue Agricultural Center, Vincennes, IN, in 2022 to determine the effect of sweetpotato cultivar on the critical weed-free period. The experiment was a split-plot design, with weed-free interval treatments as the main plot factor and cultivar as the subplot factor. The three cultivars used were 'Covington', 'Monaco', and 'Murasaki'. Weeds were removed by hand and allowed to establish and compete with the crop beginning at 0, 14, 21, 28, 35, or 42 d after transplanting (DAP). As the weed-free interval increased from 0 to 42 DAP, predicted total yield increased from 19 kg ha(-1) to 20,540 kg ha(-1) for Covington, 3 kg ha(-1) to 11,407 kg ha(-1) for Monaco, and 125 kg ha(-1) to 13,460 kg ha(-1) for Murasaki at the Lafayette location. At Vincennes, as the weed-free interval increased from 0 to 42 DAP, predicted total yield increased from 14,664 kg ha(-1) to 33,905 kg ha(-1) for Covington, 4,817 kg ha(-1) to 18,059 kg ha(-1) for Monaco, and 12,735 kg ha(-1) to 21,105 kg ha(-1) for Murasaki. A threshold of <= 10% total yield reduction was achieved by maintaining sweetpotatoes weed-free 24 DAP for Covington, 20 DAP for Murasaki, and 33 DAP for Monaco.