WHEN CROPS BECOME WEEDS: EFFECTS OF FULL SEASON INTERFERENCE FROM ROUNDUP READY~(R) COTTON OR SOYBEAN

摘要

Research was conducted in 2004 at the Northeast Research Station in St. Joseph, La and in Lewiston, Rocky Mount, and Clayton North Carolina to determine the competitiveness of Roundup Ready (RR) cotton and RR soybean as weeds in RR soybean and RR cotton crops, respectively. In St. Joseph, PM 1218 BR cotton and DP 5644 RR soybean were evaluated as both the crop and weed. In North Carolina, only FM 989 RR cotton as a crop was evaluated with Asgrow 6202 RR soybean as the weed species. Weeds were plantedwith the crop approximately two inches from the drill and thinned to 0, 1, 2, 4, 8, 16, and 32 plants per 20 row ft following emergence. Heights of up to 4 weed and crop plants were recorded weekly for a total of 10 wk in St. Joseph and 14 wk in North Carolina. Crop yield was determined following mechanical harvesting. The experiments were designed as a randomized compete block with four replications. Data were subjected to analysis of variance and regression analysis.