Agriculture, Pêche et Aquaculture
Department of Agriculture, Aquaculture and Fisheries
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  Refinement of Acetic Acid Application Parameters for Weed Control in Conventional and Organic Cranberry Production

G.L. Graham1, C. Berthélémé1, R. Tremblay1 and G. Thebeau2

Parter: New Brunswick Cranberry Growers Association

Abstract: Competition from weeds in cranberry beds continues to be a problem for this industry in New Brunswick. This problem is even worse within organic production as weed control options are limited to soil acidification by sulphur applications and hand weeding. Both methods are costly in terms of time and economics. Acetic acid has been evaluated as a foliar spray or injected near the root zone of weeds with specifically designed injectors in both Quebec and New Brunswick. Two New Brunswick locations under conventional and transitional management were selected to evaluate acetic acid application for weed control. Two experiments were conducted at each location. One experiment examined the effect of injection of acetic acid near the root zone of weed species, where acetic acid rate, timing and volume were evaluated. The other examined the effect of foliar applications of acetic acid at different concentrations and water volumes. In the injection experiment at the Tracy location, crop injury was a greater concern. Less crop injury was noted from the 6% concentration, one injection per weed and early season injections. The two injections at the Mid and Late timing gave significantly higher crop injury than the other treatments. Meanwhile, weed control was greater from the Mid and Late season applications. No significant crop injury was noted at the Saint Charles location for the injection treatments. Weed control was higher for the 9 and 12 % concentration treatments. Overall, the injection method would be best suited for spot application of weeds occurring in low levels. Injections for high weed populations could cause unacceptable crop injury. This method is also suited for weeds with distinct root structure. An application of at least 6% acetic acid at 30 ml per plant would be required for adequate weed control. There was no crop injury measured at both locations for foliar treatments. Weed control was relatively low, and may not be commercially acceptable to producers. Weed control improved at higher concentration and water volume at application, with the 6% and 2000 L/ha application volume giving the highest level of weed control in both trials, followed by 6%-1000 L/ha and 4%-2000 L/ha. Due to the variability between sites evaluated, additional testing is needed to determine the appropriate rate and timing for proper weed control under New Brunswick conditions.

1NB Department of Agriculture and Aquaculture, Crop Development Branch, P. O. Box 6000, Fredericton, NB E3B 5H1
2NB Department of Agriculture and Aquaculture, Regional Agri-Business Development, 26 Acadie Street Bouctouche, New Brunswick E4S 2T2 Canada

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