A research trial was established in 1986 in the southern interior of British Columbia to study the effects of glyphosate applied at 3 and 6 L/ha (1.05 and 2.1 Kg ai/ha) and manual cutting for release of 4-year-old planted Douglas-fir seedlings from the Mixed Hardwood Shrub Complex vegetation. Douglas-fir seedlings and three target species (paper birch, thimbleberry, and fireweed) were assessed for 3 years following treatment, and then again in the ninth year.
Reductions in cover and height of birch following broadcast glyphosate application significantly improved Douglas-fir growth; however, because birch is resistant to Armillaria root disease, helps improve long-term productivity, and enhances biodiversity, care should be taken not to affect birch more than necessary to ensure acceptable Douglas-fir performance.
FRDA Research Report 257 (2514 KB)
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Updated July 24, 2015