Dissipation and Transport of Clopyralid in Soil: Effect of Application Strategies

• Published in: Journal of agricultural and food chemistry Vol. 59; no. 14; pp. 7891 - 7895
• Main Authors: Sakaliene, Ona, Rice, Pamela J, Koskinen, William C, Blažauskienė, Gintarė
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Washington, DC American Chemical Society 27-07-2011
• Subjects: Biological and medical sciences; Cereal and baking product industries; Environmental Chemistry; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Handling, storage, packaging, transport; Herbicides - chemistry; Kinetics; Picolinic Acids - chemistry; Soil - analysis; Weed Control - methods; desmedipham; clopyralid; soil dissipation; leaching; buckwheat; Soils; Pseudocereals; Buckwheat; Transport; Application; Leaching
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/jf2012503

At present there are no herbicide uses 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 into 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 coapplication with desmedipham on its degradation and transport. Clopyralid dissipation was rapid; 50% dissipation times, in the surface 5 cm, averaged over the 4 years of the study, were <7 days. Application rate (90 versus 180 g ai ha–1), timing (pre-emergence versus postemergence), and coapplication with desmedipham (360 g ai ha–1) did not significantly influence clopyralid dissipation. Clopyralid dissipation by leaching was not a significant factor; at 7–21 days after application, <8 μg kg–1 was found at the 10–20 cm depth. Understanding the dissipation of herbicides and the influence of application strategies on herbicide fate will allow for informed decisions and improved efficacy of weed control. On the basis of the results of this research, weed scientists can now determine whether increased rates of clopyralid would provide sufficient residual chemical for adequate weed control without crop injury.