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| Department of Agriculture, Aquaculture and Fisheries |
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Abstract: Lambkill (Kalmia angustifolia), rhodora (Rhododendron canadense) and bracken fern (Pteridium aquilinum)
are potentially difficult weeds to control in wild blueberry fields. They are generally present at high density before
establishment of the field and can interfere with production during subsequent cropping years if they escape hexazinone
treatment. Spring herbicide application may provide another application window for these weeds. A trial was
established in a wild blueberry field which was being brought into commercial production in the Lavillette region of
New Brunswick. None of the herbicides evaluated combined consistent weed control with adequate crop injury ratings.
Imazethapyr and both triclopyr rates caused significant blueberry injury over all rating dates. Triclopyr was the only
treatment with lambkill control over multiple rating timings. Both sulfentrazone and chlorimuron–ethyl
suppressed lambkill populations early after application. Applications of granular hexazinone after blueberry emergence
suppressed lambkill populations on the final rating date. Only high rates of triclopyr suppressed rhodora populations,
while all other herbicide treatments did not provide significant control. Mesotrione alone, hexazinone followed by
mesotrione and sulfentrazone had high levels of bracken fern control on the first rating date, but all showed significant
regrowth by the end of the trial period. Chlorimuron ethyl and granular hexazinone applications suppressed bracken
fern. Some of the products with good crop safety (BAS 800H, isoxaflutole, and thiencarbazone) should be evaluated for
additional weed targets to determine if they would be suitable within blueberry production. Mesotrione alone would not
provide adequate weed control for land clearing purposes. The most promising treatment was late applications of
granular hexazinone. This practice should be evaluated further. The trial will not be continued into the crop year as the
co–operating grower is changing the management strategy for the field area.