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ARS Home » Research » Publications at this Location » Publication #106138
Title: WEED MANAGEMENT IN NARROW AND WIDE ROW GLYPHOSATE-RESISTANT SOYBEAN (GLYCINE MAX)

Author
item YOUNG, BRYAN - SOUTHERN ILLINOIS UNIV
item YOUNG, JULIE - SOUTHERN ILLINOIS UNIV
item GONZINI, LISA - UNIV OF ILLINOIS
item HART, STEPHEN - UNIV OF ILLINOIS
item Wax, Loyd
item KAPUSTA, GEORGE - SOUTHERN ILLINOIS UNIV

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/10/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: We conducted studies at three locations for three years in Illinois to compare various glyphosate and standard herbicide treatments on glyphosate-resistant soybeans grown in three different row spacings (19, 38 and 76cm). Glyphosate treatments caused only minimal injury at any time to the soybean crop. Single glyphosate treatments were very effective in managing giant foxtail; however, control was increased by reducing row spacing from 76 to 19 cm and by applying sequential applications of glyphosate in 4 of 8 site-years. Common waterhemp control was good with glyphosate, but could be increased with increased rate of application, sequential applications, and narrowing the row spacing. Velvetleaf control was variable with glyphosate, but was most consistent with combinations of narrow rows, higher rates, and sequential or split applications. Soybeans treated with glyphosate yielded higher in 3 of 8 site-years with the combination of narrow rows and sequential applications. Glyphosate treatments resulted in soybean yields equal to or better than those achieved with standard herbicide treatments, and were only slightly less than yields from hand weeded, untreated plots. These studies showed various ways to optimize weed management using a combination of herbicides, row spacing, and glyphosate-resistant soybean, and will be useful to public and private sector personnel who are conducting research and developing weed management guidelines for soybean production.

Technical Abstract: Field experiments were conducted over three years at three locations in Illinois to evaluate the efficacy of glyphosate in glyphosate-resistant soybean planted in 19, 38, and 76 cm rows. Minimal soybean injury (less than 10%) was observed from any glyphosate treatment. Glyphosate treatments controlled 82 to 99% of giant foxtail. Decreasing the soybean row spacing from 76 to 19 cm or applying sequential applications of glyphosate increased giant foxtail control in at least 4 of 8 site-years. Common waterhemp control was increased as soybean row spacing was decreased. Applying sequential glyphosate applications or increasing the glyphosate rate frequently increased common waterhemp control in 76 cm rows. Velvetleaf control with glyphosate was variable ranging from 48 to 99%. Decreasing soybean row spacing, utilizing sequential applications, or increasing the glyphosate rate improved velvetleaf control in at least 4 of 8 site-years. Decreasing soybean row spacing or applying sequential glyphosate applications increased soybean yield in 3 of 8 site-years. Glyphosate treatments generally resulted in weed control and soybean yield equal to or greater than the standard herbicide treatments. However, glyphosate treatments yielded less than the hand weeded in 4 of 8 site-years, suggesting that weed control from glyphosate treatments was sometimes inadequate.