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Bioforest Technologies
Inc. was contracted to monitor the impact of the 2003 spray
program and to determine if the numbers of budworm larvae
were sufficiently high to warrant continuation of the spray
program in 2004. Their sampling methods were similar to those
used by Sask. Environment in their decision-making processes.
A total of 19 tree
plots were established, including three outside the spray
area for control purposes.
The main conclusions
in the report were as follows:
• Overall, trees
in the treated plots had a greater proportion of living tops
bearing needles than white spruce in the untreated plots.
An average of 43.7 % of the trees in the treated area had
living tops bearing needles,compared with 22.6% in the untreated
plots. However, there was considerable variability throughout
the community.
• Overall, current defoliation of the white spruce averaged
60.3% in the treated plots, compared with 90.7% in the untreated
control plots. In effect, in untreated plots, more than 90%
of new growth was destroyed by the budworm.
• The Cumulative Defoliation Index (CDI) showed that
cumulative defoliation in treated areas was lower in the treated
plots compared to the untreated plots. The CDI index was 2.3
in the treated plots and 3.1 in the untreated plots. A CDI
index <2 indicates the trees are in good to excellent condition;
a CDI index >2 indicates the trees are in fair to poor
condition. In other words, the higher the index, the poorer
the condition of the trees.
• Defoliation surveys were conducted at four locations
in the spray zone, including: Beaver Glen, Bittern Street,
Trailer Park and Golf Course Hole No. 3 – Tee Off. Based
on the number of larvae per 10 sq.m. we would expect moderate
defoliation in the first three locations and severe defoliation
in the golf course location, if no spraying were done. The
number of L2 larvae per sq.m. ranged from 373 in the Trailer
Park to 1565 at the Golf Course site. In comparison, the number
of L2 larvae per 10 sq.m. at an untreated control plot was
3,832.
All in all, it can
be concluded that the 2003 spray program was effective in
reducing defoliation in the white spruce; however, the job
is not yet finished.
Consequently, Parks
Canada and The Waskesiu community Council have decided to
proceed with the 2004 spray program on the same basis as the
2003 program.
The goal is to reduce
defoliation from the present 60% level to about 40%, which
is equivalent to the provincial program targets. As we have
said all along, the goal is not to eradicate the budworm ,but,
rather, to reduce populations to improve the health (CDI)
of the white spruce thereby giving them a fighting chance
to survive.
Submitted by: Herve
Langlois, chair, Vegetation Management Committee
March 22, 2004
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