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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICALLY BASED INTEGRATED MANAGEMENT OF INVASIVE AQUATIC AND RIPARIAN WEEDS

Location: Exotic and Invasive Weeds Research

Title: Effect of a combination of two rice herbicides on the cyanobacterium, Nostoc spongiaeforme

Authors
item Spencer, David
item Liow, Pui-Sze
item Lembi, Carole -

Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 17, 2009
Publication Date: September 30, 2009
Citation: Spencer, D.F., Liow, P., Lembi, C.A. 2009. Effect of a combination of two rice herbicides on the cyanobacterium, Nostoc spongiaeforme. Journal of Aquatic Plant Management. 47:145-147.

Interpretive Summary: Cyanobacteria grow in California rice fields where they form large mats that may smoother seedlings or cause them to dislodge, resulting in yield loss. The most troublesome species is Nostoc spongiaeforme. It is very difficult to control using currently accepted methods, i.e., aerial applications of copper sulfate. Two herbicides commonly used in rice production are Londax and Shark. Discussions with growers indicated that they had observed less severe algal problems in fields which had been treated with combinations of these herbicides. The purpose of these experiments was to evaluate the effect of a Londax-Shark mixture on growth of Nostoc spongiaeforme. In three of the four experiments the treatments had no statistically detectable influence on Nostoc spongiaeforme growth rates. In one experiment, there was a statistically significant reduction in growth rate, by 12% at the highest level of the Londax-Shark mixture examined. Thus, it does not appear that this herbicide mixture will be useful in the management of Nostoc spongiaeforme in California rice fields. Comparing our results with previously published work indicates that cyanobacteria appear to be susceptible to bensulfuron-methyl only at concentrations that are much higher than those used in rice fields.

Technical Abstract: Cyanobacteria grow in California rice fields where they form large mats that may smoother seedlings or cause them to dislodge, resulting in yield loss. The most troublesome species is Nostoc spongiaeforme. It is very difficult to control using currently accepted methods, i.e., aerial applications of copper sulfate. Two herbicides commonly used in rice production are Londax and Shark. Discussions with growers indicated that they had observed less severe algal problems in fields which had been treated with combinations of these herbicides. The purpose of these experiments was to evaluate the effect of a Londax-Shark mixture on growth of Nostoc spongiaeforme. In three of the four experiments the treatments had no statistically detectable influence on Nostoc spongiaeforme growth rates. In one experiment, there was a statistically significant reduction in growth rate, by 12% at the highest level of the Londax-Shark mixture examined. Thus, it does not appear that this herbicide mixture will be useful in the management of Nostoc spongiaeforme in California rice fields. Comparing our results with previously published work indicates that cyanobacteria appear to be susceptible to bensulfuron-methyl only at concentrations that are much higher than those used in rice fields.

Last Modified: 7/22/2014
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