G.L. Graham and G. Chiasson
Partner: Bleuets NB Blueberries
Abstract: Lambkill (Kalmia angustifolia) is a potentially difficult weed to control in newly established wild blueberry fields as
it can interfere with production during subsequent cropping years if it escapes hexazinone treatment. As lambkill is still actively growing in
the fall while the crop is not, it may be possible to take advantage of greater blueberry tolerance while not sacrificing the level of lambkill
control from a glyphosate application. A trial was established in the fall of 2008 after the first growing cycle within a newly developed wild
blueberry field in the Lavillette region of New Brunswick. The trial design was a randomized complete block design with a two by five factorial
treatment design, examining two rates of glyphosate and five timings of hexazinone application. Minor crop injury, represented by a delay in crop
emergence, was found after glyphosate application. Recovery occurred to commercially acceptable levels in subsequent ratings. Glyphosate treatment
resulted in a two-fold increase in crop yield, showing no long term effect from the early injury. Slight activity was observed on lambkill populations
with all hexazinone alone applications, provided herbicide application occurred before the rating date. The level of control from hexazinone alone is
lower than what is commonly found in commercial production. All glyphosate treatments resulted in control of lambkill. There was no significant lambkill
control benefit to the addition of any hexazinone treatment to a previous glyphosate treatment. The use of glyphosate within early field establishment
years for wild blueberry represents a safe, cost effective and efficacious management tool for lambkill control. The potential registration of this treatment
through the User Requested Minor Use Label Expansion should be explored.
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