|Elmore, Clyde - UC DAVIS|
|Roncoronni, John - UC DAVIS|
Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 7, 2003
Publication Date: June 1, 2003
Citation: Spencer, D.F., Elmore, C.L., Ksander, G.G., Roncoronni, J.A. 2003. Influence of dilute acetic acid treatments on survival of american pondweed winter buds in the nevada irrigation district, california. Journal of Aquatic Plant Management. 41(2):65-68. Interpretive Summary: Aquatic weeds clog irrigation systems, crowd out desirable native vegetation, and make waterways unsuitable for boating, fishing, and swimming. American pondweed grows very rapidly from underground structures called winter buds. In previous studies we demonstrated that underground structures similar to winter buds produced by other aquatic weeds could be killed by drenching the soil with dilute solutions of acetic acid equivalent to half strength vinegar. This study was a large scale test of the effectiveness of this treatment under field conditions. We applied to rates of dilute acetic acid solutions using drip tape (commonly used in irrigation) or soaker hoses to 50 foot x 15 foot plots in the Nevada Irrigation District Canal in northern California. The treatments were made in March when flowing water was absent from the canal. American pondweed dry weights in the plots measured 5 weeks after the treatments were reduced more than 90 % in some cases. Other samples measured after 11 weeks showed similar results. A low-growing spikerush, considered to be a more desirable species in irrigation systems, was unaffected by the treatment. These results imply that it may be possible to manage American pondweed in dry irrigation canals with dilute solutions of acetic acid. Killing underground reproductive structures of aquatic weeds is a new management approach.
Technical Abstract: American pondweed (Potamogeton nodosus Poir.) is commonly found in northern California irrigation canals. The purpose of this study was to test the hypothesis that exposure of American pondweed winter buds to dilute acetic acid under field conditions would result in reduced survivorship and subsequent biomass. The treatment consisted of either adding either 1703 or 3406 l (1 or 2 acre-inches) of 2.3% acetic acid per 83 m2 plot. Acetic acid was applied using either drip tape (6 plots) or soaker hoses (3 plots). Six weeks after treatment, we collected nine samples from each plot for biomass determination. American pondweed biomass was reduced (ANOVA, P < 0.001) by the acetic acid application. The reduction was observed for samples collected from the sides as well as the canal bottom when 3406 l per plot were applied. At the lower rate, there was slightly more biomass on the sides of the canal. These results confirm findings from earlier laboratory/greenhouse experiments, and suggest that application of dilute acetic acid solutions (2.3%) by drip irrigation tape may be useful in the management of American pondweed in systems that can be have the water removed temporarily.