Sergio Andrés Herrera-Jiménez1 and Julián Fernando Mateus-Rodriguez2 #
1Corporación Colombiana de Investigación Agropecuaria AGROSAVIA, C.I. La Selva, Rionegro, Colombia
2Centro de Investigación de la caña de azúcar de Colombia CENICAÑA, Cali, Colombia
Weed competition reduces yield due to resource competition and demands integrated management strategies based on critical weed-free periods (CWFP) and acceptable yield loss thresholds (AYL). It is crucial to analyze the competitive ability of problematic species at different densities. Experiments were conducted to determine the CWFP in two sugarcane varieties (CC 05-430 and CC 09-066) with 12 weed control treatments. Dry weight, leaf area index, height, photosynthesis, stomatal conductance, cane yield (TCH), and sucrose content were evaluated. A second experiment assessed the competition of the CC 05-430 variety against four weed species: Merremia aegiptia, Rottboellia cochinchinensis, Ipomoea tiliacea, and Megathyrsus maximus, at different densities. Stem population, height, internodes, TCH, and sucrose content were measured. The results showed that competition reduced TCH by up to 50% in both varieties, although the CWFP varied. For CC 05-430, the CWFP were: 38–1483, 76-1149, and 122-897 GDD (accumulated degree days) for 5%, 10%, and 15% AYL, respectively. For CC 09-066, they were 105–1543, 252-1193, and 405-996 GDD. In the density experiment, higher weed densities reduced stem population, height, internodes, and sucrose. TCH losses were observed due to a single weed plant, ranging from 9% to 42%, depending on the weed species (Merremia aegiptia 28%, Rottboellia cochinchinensis 42%, Ipomoea tiliacea 9%, and Megathyrsus maximus 41%). Weed interference affects crop growth, decreasing TCH and final sucrose yield. These findings allow for the adjustment of integrated management strategies to minimize the impact of weed competition in sugarcane cultivation.