ECONOMICS OF COMMON COCKLEBUR CONTROL IN SOYBEAN PRODUCTION

The effects of common cocklebur (Xanthium pensylvanicum Wallr.) on soybean [Glycine max (L.) Merr.] yields, grades and net returns were determined by regression analysis of data from 450 research plots during 1971-1973. Common cocklebur control 0-100% was achieved by various combinations of premergence and postemergence practices. Foreign matter in soybean seed samples was 0.7% with total common cocklebur control and 5.1% with no control. At least 70% control of common cocklebur was required to avoid deductions from gross harvested weights due to seed moisture levels exceeding 13%. Small discounts for damaged kernels occurred when common cocklebur control was < 40%. With 100% common cocklebur control, the estimated US soybean grade was 1.3. Failure to control common cocklebur resulted in a predicted grade of 3.9. When adjusted for various weight discounts, soybean yields were 1170 kg/ha without control of common cocklebur and 1890 kg/ha for 100% control. Soybean yields were increased about 6% for each 10% increase in common cocklebur control.