Project Summary

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Introduction:

The use of VISION® (glyphosate) herbicide during the year of planting as a post plant treatment is gaining interest in forestry as an operational vegetation management tool. Data on conifer tolerance to post plant VISION® treatments during the year of planting is required.

The SX trial SX93701Q (Figure 1. (60k gif))was established to provide information on conifer tolerance to VISION® herbicide. The trial was initiated as a collaborative effort between Vancouver Regional staff, Research Branch staff and Regional Vegetation Management Specialists.

Objectives:

• The primary objective of this trial is to acquire and report data on conifer tolerance to application of VISION® (glyphosate) herbicide applied as a post plant treatment during the year of planting.
• A secondary objective of this trial is to assess the effectiveness of VISION® (glyphosate) herbicide applied as a post plant treatment during the year of planting.

Treatments:

Layout:

• 60 planted Douglas-fir seedlings were selected to monitor conifer response to three rates of VISION® (glyphosate) herbicide
• Application of the herbicide consisted of a 2 m X 2 m seedling centered spot application
• Each treatment was replicated on 15 randomly selected Douglas-fir seedlings
• All herbicide treatments were applied between 3-4 pm during sunny and clear conditions with no wind (0-2 kpm)
• Douglas-fir seedling tolerance was assessed pretreatment and post treatment on the degree of visible foliage and bud damage as well as height and diameter growth
• Survival, foliage and stem condition and the number of healthy buds on the leader were also assessed
• Pretreatment non-crop species vegetation assessments of % cover and modal height were taken within a 1.26 m radius plot centered on each tagged seedling
• Douglas-fir seedlings were assessed pretreatment (Sept. 1993), one month post treatment and one year post treatment
• Further post treatment assessments were recommended until at least year 5 (Fall of 1998)

Sites:

1. Brett Creek

Major Findings:

At treatment during August 1993,  the majority of seedling leaders had set bud with well developed bud scales however, several individuals appeared to have dead leaders and necrotic buds related to the nursery top pruning treatment. Statistical analysis suggested no difference in leader bud numbers between the treatments at the pretreatment and one month post treatment assessment dates.

By the fall of 1994 (one year post treatment), assessment of leader, foliage and stem condition and the amount of visible needle damage was inconclusive. Needle damage such as chlorosis, mottling, browning, necrosis and needle drop was evident however, there was no visible needle damage to the 1993 and 1994 foliage which could be attributed to the herbicide treatments.

Statistical analysis suggested no significant difference in seedling height and number of leader buds (other assessment). However, seedling basal diameter was found to be significantly larger in the 2 kg/ha glyphosate treatment when compared to the untreated control treatment.

References and Publications (Click on Highlighted References to Obtain an Electronic Copy in PDF Form):

Harper, G.J. P.G. Comeau, and B.S. Biring. 1997. Conifer tolerance to Vision herbicide application in the year of planting. Abstract, Expert Committee on Weeds, Charlottetown.

Harper, G.J. and P.G. Comeau. 1996. Conifer tolerance to Vision herbicide application in the year of planting. Research Report, Expert Committee on Weeds, 1996 National Meeting, December 9-12, Victoria.

Harper, G.J., P.G. Comeau, B. Biring, and B. D'Anjou. 1995. Conifer tolerance to VISION® herbicide application in the year of planting. Establishment and 1st year progress report for SX93701Q. B.C. Min. For., Research Branch, Victoria.

Harper, G.J., P.G. Comeau and B. D'Anjou. 1994. Conifer tolerance to Vision herbicide application in the year of planting. Expert Committee on Weeds, Research Report, Western Canada Section Meeting, December 5-8, 1994, Saskatoon, Sask., Vol 2, p. 1015.

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Last Updated: May 29, 1998.