EFFECT OF ENDOTHALL AND GLYPHOSATE ON A NATIVE BARRENBERRY AND LOWBUSH BLUEBERRY STAND

The salt of endothall (7-oxabicyclo{2.2.1} heptane-2, 3-dicarboxylic acid) was applied either in mid-July or mid-August to a mixed stand of barrenberry (Aronia melanocarpa (Michx.) Ell.) and blueberry (Vaccinium angustifolium Ait.) in a commercial lowbush blueberry field. The endothall treatment at 0.58 kg/ha defoliated all blueberry plants and caused a partial defoliation of barrenberry plants. Ten or eleven days later plants were treated with 0, 0.56, 1.12 or 2.24 kg/ha glyphosate (N-{phosphonomethyl}glycine5. Plots were covered with straw in the fall and burned the following spring. Blueberry and barrenberry plant stands were determined before and 1 yr after treatment. The effects of treatments on blueberry and barrenberry vigor and potential blueberry productivity were assessed. Higher rates of glyphosate preceded by endothall resulted in a 61–87% reduction in barrenberry stand but had no effect on blueberry stand. High rates of glyphosate reduced the height of new barrenberry and blueberry stems. Herbicide treatments and date of application had no influence on the number of fruit buds per blueberry stem.