Response Surface Analysis of Control of Red Alder and Vine Maple with Glyphosate-Imazapyr and Triclopyr-Imazapyr
Quadratic response functions were demonstrated for predicting crown reduction of red alder (Alnus rubra) and vine maple (Acer circinatum) after application of the herbicides glyphosate and triclopyr in combinations with imazapyr. Relationships between crown reduction and the application dates and rates were explored with data from five experiments previously conducted in Oregon in order to estimate optimal timing and optimal rates for each herbicide. The best crown reduction with glyphosate-imazapyr was achieved in the Cascade Mountain foothills with June or July applications and in the Coast Range with August or September applications. Control of red alder was best with 0.05 to 0.09 lb (ae/ac) imazapyr; the additive effect of glyphosate rate was more important in July than in August applications. The optimum imazapyr rates for vine maple may be outside the range of rates included in the studies, and rainfall shortly after the July application compromised the results for one study. Compared to crown reduction of vine maple with the individual herbicides, the effect with glyphosate-imazapyr varied from none to slightly positive, and that with triclopyr-imazapyr from slightly negative to additive. The response model accounted for 69-88% of the observed variation in crown reduction of vine maple. The model for red alder accounted for 44% of the variation in crown reduction. West. J. Appl. For. 10(4):127-132.
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Document Type: Journal Article
Affiliations: Department of Forest Science, College of Forestry, Oregon State University, Corvallis, OR 97331
Publication date: 01 October 1995