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| Department of Agriculture, Aquaculture and Fisheries |
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Abstract: Lambkill (Kalmia angustifolia) and rhodora (Rhododendron canadense) are weeds that are potentially
difficult to control in wild blueberry fields. They are generally present at high densities before establishment of the
field and can interfere with production during subsequent cropping years if they escape hexazinone treatment. The
addition of a hexazinone treatment in the spring following a fall herbicide application could contribute to improved
weed control. A trial was established in a commercial wild blueberry field in the Lavillette region of New Brunswick in
the fall after blueberry harvest. The trial design was a split plot with the main plots represented by the herbicide applied
in the fall and the sub–plots the spring herbicide treatment. A spring hexazinone application, at the lowest
registered rate, had no effect on crop injury or weed control, so this repeated application would be possible but may not
be economical for producers. The low application rate of hexazinone may not have been high enough to have an effect
on the species evaluated. There was early crop injury from all Group 4 products, with recovery over later ratings and no
significant yield effect. All fall herbicides evaluated offered adequate lambkill control in the sprout year, with the
highest control level in the glyphosate treatments. Lambkill re–growth was noted for glyphosate treatments.
Control from the glyphosate–IPA salt had decreased as compared to the glyphosate–K formulation in the
crop year. Rhodora control was more problematic, with only dicamba plus 2,4–D ester offering suppression of
the weed on the final rating date. Additional fall evaluations are required, including the effect of mowing date and
additional herbicide applications for control of both lambkill and rhodora.