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ARS Home » Midwest Area » St. Paul, Minnesota » Soil and Water Management Research » Research » Publications at this Location » Publication #225076
Title: Early Season Weed Suppression in Buckwheat Using Clopyralid

Author
item SAKALIENE, ONA - LITHUANIAN INST OF AGRI
item CLAY, SHARON - SOUTH DAKOTA STATE UNIV
item Koskinen, William
item ALMANTAS, GEDIMINAS - LITHUANIAN INST OF AGRI

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2008
Publication Date: 12/1/2008
Citation: Sakaliene, O., Clay, S.A., Koskinen, W.C., Almantas, G. 2008. Early Season Weed Suppression in Buckwheat Using Clopyralid. Weed Technology. 22(4):707-712.

Interpretive Summary: Buckwheat is a broadleaf crop that, while planted worldwide in cooler climates and used for human food and animal feed, is considered a minor crop. Established buckwheat can smother and suppress weed growth due to its aggressive growth and allelopathic compounds contained in its shoots. However during early establishment, buckwheat is a poor competitor. Currently there are no herbicides registered for direct crop application. This 4-year Lithuanian study examined weed control using the broadleaf herbicides clopyralid and desmedipham alone or in combination at several rates. Weed control one month after application for most weeds was limited. Buckwheat without treatment suppressed weed growth by harvest, but reductions were much greater with all the herbicide treatments. Unfortunately, crop injury symptoms, especially at the slightly higher rates of clopyralid, alone or in mixture, were observed with the treatments. The injury symptoms on the buckwheat were expected as clopyralid is rated as acceptable for wild buckwheat control. Buckwheat vegetation did recover, with most symptoms outgrown by about 5 weeks after application. However, in most cases, yields were not greater than the untreated control. Therefore, for the grower the benefit and value of gaining additional weed control with the herbicide application must be carefully weighed against the cost of herbicide and application.

Technical Abstract: Buckwheat is a broadleaf crop that, while planted worldwide in cooler climates and used for human food and animal feed, is considered a minor crop. Established buckwheat can smother and suppress weed growth due to its aggressive growth and allelopathic compounds contained in its shoots. However during early establishment, buckwheat is a poor competitor. Currently there are no herbicides registered for direct crop application. This 4-year Lithuanian study examined weed control using the broadleaf herbicides clopyralid and desmedipham alone or in combination at several rates. Most applications were applied at the 1-leaf stage of crop growth, however, one rate of clopyralid was applied preemergence in two of the four years. Buckwheat injury was evident within a few days after application (or emergence) with all treatments, but by harvest, the crop outgrew the injury. Weed densities and biomass were only minimally affected by herbicide application 1 month after application. At harvest, weed biomass was reduced by about 50% when compared with weed biomass in the untreated control. With few exceptions, buckwheat yield in all herbicide treated plots was similar to the untreated control in most years. Based on these data, the benefits and values of additional weed control with these herbicides must be carefully weighed against the herbicide and application cost and early season crop injury.