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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #131275
Title: WEED MANAGEMENT SYSTEMS FOR CONVENTIONAL AND GLYPHOSATE-RESISTANT SOYBEAN WITH AND WITHOUT IRRIGATION

Author
item Heatherly, Larry
item Elmore, Carroll
item SPURLOCK, STAN - MISS. STATE UNIV.

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/17/2002
Publication Date: 12/2/2002
Citation: HEATHERLY, L.G., ELMORE, C.D., SPURLOCK, S.R. 2002. WEED MANAGEMENT SYSTEMS FOR CONVENTIONAL AND GLYPHOSATE-RESISTANT SOYBEAN WITH AND WITHOUT IRRIGATION. AGRONOMY JOURNAL. Vol. 94:1419-1428.

Interpretive Summary: Low profits are common from soybean plantings in the midsouthern US. This often is a result of high input costs associated with weed management. Weed management costs can be controlled by using either conventional or transgenic cultivars and manipulating herbicide inputs. Use of glyphosate- resistant soybean cultivars and glyphosate in a nonirrigated or low yield environment resulted in greater profit than using conventional cultivars with conventional herbicides. In an irrigated or high yield environment, using conventional vs. glyphosate-resistant cultivars resulted in greater profit. Use of preemergent followed by postemergent weed management vs. using only postemergent weed management was not necessary for achieving highest yield or net return with either conventional or glyphosate- resistant cultivars. In fact, use of preemergent followed by postemergent management resulted in lower profits in some cases. These results will allow producers to decide on the best weed management system for soybean grown in both nonirrigated and irrigated environments in the midsouthern US.

Technical Abstract: Management inputs that maximize economic return from the Early Soybean Production System (ESPS) have not been evaluated fully. Field studies were conducted from 1996 through 1999 on Sharkey clay soil at Stoneville, MS. The objective was to determine the effect of weed management on yield and net return from early-planted Maturity Group (MG) IV and MG V glyphosate-resistant (GR) and conventional (CONV) soybean cultivars grown in the ESPS with (I) and without (NI) irrigation. Weed management treatments were: 1) preemergent (PRE) broadleaf followed by postemergent (POST) broadleaf and grass weed management (PRE + POST); and 2)POST broadleaf and grass weed management (POST). Weed management was done exclusively with herbicides. Under the conditions of this study, use of GR vs. CONV cultivars in an NI or low yield environment resulted in greater profit. In an I or high yield environment, use of CONV vs. GR cultivars resulted in greater profit. Use of PRE + POST vs. using only POST weed management was not necessary for achieving highest yield or net return with either CONV or GR cultivars.