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United States Department of Agriculture

Agricultural Research Service

Research Project: PROTECTING SURFACE AND GROUND WATERS IN EMERGING FARMING SYSTEMS OF THE NORTH CENTRAL UNITED STATES

Location: Soil and Water Management Research

Title: Dissipation and transport of clopyralid in soil: Effect of application strategies

Authors
item Sakaliene, Ona -
item Rice, Pamela
item Koskinen, William

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 21, 2011
Publication Date: July 5, 2011
Citation: Sakaliene, O., Rice, P.J., Koskinen, W.C. 2011. Dissipation and transport of clopyralid in soil: Effect of application strategies. Journal of Agricultural and Food Chemistry. 59(14):7891-7895.

Interpretive Summary: Currently there are no herbicides registered for broadleaf weed control in buckwheat. Clopyralid, mixed with desmedipham, was anticipated to provide early-season broadleaf weed suppression with minimal crop injury. However, field trials resulted in limited success which brought to question the fate and availability of clopyralid for weed control. A 4-year field study was conducted in Lithuania to evaluate the fate of clopyralid in sandy loam soil and the influence of application rate, application timing, and co-application with desmedipham on its degradation and transport. The concentration of clopyralid in the soil diminished rapidly. In less than 10 d concentrations of clopyralid were half of the quantity applied and less than 15% remained in the top 20 cm of the soil at 21 d. Application rate (90 versus 180 g ai ha-1), timing (preemergence versus postemergence) and co-application with desmedipham (360 g ai ha-1) did not significantly influence clopyralid fate. Understanding the degradation and transport of herbicides and the influence of application strategies on herbicide fate allows for informed decisions and improved efficacy of weed control. Based on the results of this research, weed scientists can now determine whether increased rates of clopyralid, which in turn would increase persistence, will provide adequate weed control without crop injury in Northern climates.

Technical Abstract: At present there are no herbicides registered for broadleaf weed control in buckwheat. Clopyralid, mixed with desmedipham, was anticipated to provide early-season broadleaf weed suppression with minimal crop injury. However, field trials resulted in limited success which brought to question the fate and availability of clopyralid for weed control. A 4-year field study was conducted in Lithuania to evaluate the dissipation of clopyralid in haplic luvisol sandy loam soil and the influence of application rate, application timing, and co-application with desmedipham on its degradation and transport. Clopyralid dissipation was rapid. In less than 10 d after application extractable clopyralid residues diminish to half of the application rate and less than 15% remained in the 0-20 cm depth at 21 d. Application rate (90 versus 180 g ai ha-1), timing (preemergence versus postemergence) and co-application with desmedipham (360 g ai ha-1) did not significantly influence clopyralid dissipation. Understanding the degradation and transport of herbicides and the influence of application strategies on herbicide fate allows for informed decisions and improved efficacy of weed control. Based on the results of this research, weed scientists can now determine whether increased rates of clopyralid, which in turn would increase persistence, will provide adequate weed control without crop injury in Northern climates.

Last Modified: 7/28/2014