CRITICAL PERIOD OF COMPETITION OF FIELD BINDWEED (Convolvulus arvensis L.) IN GRAIN SORGHUM

Abstract

Field bindweed (Convolvulus arvensis L.) is one of the most common and troublesome weeds in grain sorghum (Sorghum bicolor L. Moench) in northern Tamaulipas. Due to its high competitive ability causes sorghum yield reductions of about 50 %. From 2001 to 2003 the competition critical period of field bindweed in grain sorghum was determined in field experiments. Maximum weed-infested and weed-free periods of 0, 2, 4, 6, 8, and 16 weeks after grain sorghum emergence were maintained by hand weeding. The critical period of competition of field bindweed, to avoid losses above 5 % of yield produced by full-season weed-free treatment, was established in the first 5.5 weeks of sorghum development. Non-linear regression models showed that field bindweed competition for only one week after grain sorghum emergence caused 29, 44 y 16 % yield reduction in 2001, 2002 and 2003, respectively. Results indicated that field bindweed control practices should be initiated before grain sorghum planting to avoid early competition.