Comparison of efficacy of girdling and various rates of triclopyr ester basal applications for control of poplar spp.  Guggenmoos, S. 

Trembling aspen and balsam poplar saplings under powerlines in section 24 of 63-11-W5 northwest of Whitecourt, Alberta were treated with basal applications of 4.8g or 14.4g triclopyr ester per liter of diesel oil or girdled.  Poplar stems ranged from 1-6 cm in diameter.  Treatments were replicated 3 times with 10 sample stems per species per replicate.  Girdling was done on September 2 and 3, 1992 by stripping a minimum 2.5 cm wide band to below the cambium layer with a budding knife.  All girdling cuts were made within 15 cm of the root collar.  Basal applications with a backpack sprayer were made by applying the mixture of diesel and triclopyr in a straight stream to completely wet the lower 45 cm of the target stems on September 15, 1992.  The degree of stem kill and root suckering were assessed on September 16, 1994.

Comparison of girdling with triclopyr ester basal applications

TREATMENT Rate (g/L)1 Trembling aspen Balsam poplar Trembling aspen Balsam poplar
triclopyr ester 4.8 100 c3 100 c 0 a 0 a
triclopyr ester 14.4 100 c 100 c 0 a 0 a
girdling NA 80 b 62 b 0 a 25 b
Control 0 a 2 a 0 a 0 a

1 a.i. per L of diesel fuel

2 number of sprouts X maximum sprout length

3 Duncan’s Multiple range Test at 5% level

Both rates of triclopyr ester provided complete control of the poplar species.  The results indicate no benefit to the higher label rates for basal applications, using diesel as the diluent, for control of poplar.  While girdling provided significant stem kill of both trembling aspen and balsam poplar only the control of trembling aspen is considered good.  Girdling of balsam poplar resulted in inadequate stem kill and significant sprouting from the root collar and roots. Girdling appears to offer another vegetation control technique but research and experience will need to confirm efficacy by tree species.

(TransAlta Utilities, Sherwood Park, Alberta)