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ARS Home » Research » Publications at this Location » Publication #67684
Title: COMPARISON OF CHLOROACETAMIDE HERBICIDES FOR ANNUAL GRASS WEED CONTROL AND CROP TOLERANCE IN CONVENTIONAL AND NO-TILLAGE CORN (ZEA MAYS) PRODUCTION

Author
item HART, STEPHEN - UNIV OF ILLINOIS
item Wax, Loyd
item SIMMONS, FREDERICK - UNIV OF ILLINOIS

Submitted to: Weed Technology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: We conducted field trials for two years under different tillage, soil and environmental conditions to compare new herbicides with standard ones. All of these herbicides are chloroacetamides, are soil-applied and are effective in controlling annual grass weeds. Some are standards, others are new, and others are new formulations. We evaluated these herbicides all at one time for grass control to determine their best fit for weed management in corn. We compared the herbicides at 1/2, 1 and 2 times the normal use rates. Metolachlor, one of the standards, lasted the longest under very wet conditions, and thus provided the most consistent control, especially on lower organic matter soils. Alachlor, also used for some time, provided the shortest length of control during the season, under heavy rainfall. The new herbicides, acetochlor and SAN 582H, were activated with less rainfall than were metolachlor and alachlor, and so were the most effective under limited rainfall after application. None of the herbicides were very effective if no rainfall was received within 14 days after application. None of the herbicides caused any serious corn injury. Under normal conditions, of neither too wet nor too dry, all of the herbicides in these studies, at the 1X rate, provided very good control of giant foxtail with ample safety to the corn. These findings will be useful to those planning future weed management studies and those preparing weed management guidelines.

Technical Abstract: Field studies were conducted in 1994 and 1995 in conventional and no-till corn at four locations to compare annual grass weed control and crop tolerance to chloroacetamide herbicides applied preemergence. Herbicides included a micro-encapsulated formulation of alachlor, metolachlor, SAN 582H, and two different safener formulations with acetochlor, applied at 1/2X, X and 2X the recommended field use rates. Soils ranged from low (0.5 to 1.5%) to high 5 to 6%) organic matter for conventional tillage while no-tillage studies were conducted on high organic matter soils. No significant corn injury was observed in any of the trials. Control was not acceptable with any of the chloroacetamide herbicides applied at field use rates if adequate rainfall was not received within 14 days after applications. Acetochlor applied at 2X the field use rate on low organic matter soils in conventional tillage also provided greater giant foxtail control under low rainfall conditions relative to the other chloroacetamide herbicides. With adequate rainfall within 14 days after application, all herbicides at field use rates provide similar levels of control of giant foxtail. Giant foxtail control was greater with metolochlor than with alachlor and acetochlor in 1995. Under heavy rainfall conditions, especially on the low organic matter soils, metolachlor provided more consistent and longer control than did the other herbicides. Under limited rainfall conditions, acetochlor and San 582H were the most effective herbicides of those evaluated.