IntensIve sIlvIculture - Forest Science Labs - Research Network ...

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examined. On two sites (Summit and Marcola), seedling growth parameters were maximized at or
near full vegetation control with a tree spacing of 3 m x 3 m. On the third site (Pedee), maximum
growth response occurred between 5 and 6 msuperscript 2 of control. Herbaceous vegetation
control resulted in increased seedling growth at all sites while woody vegetation control yielded
increased seedling growth only at the Pedee site. Cumulative 3 yr herbaceous cover accounted for
68% and 41% of the variability in stem volume at Summit and Marcola, respectively. Adding
cumulative 3 yr woody cover to the model accounted for an additional 18% and 49% of the
variability in stem volume at Summit and Marcola, respectively. At Pedee, neither herbaceous nor
woody cover significantly influenced 3 yr stem volume, suggesting that factors other than
vegetation cover were responsible for differences measured.
518. Ross, D.W. and G.E. Daterman. 1994. Reduction of Douglas-fir beetle infestation of high-risk
stands by antiaggregation and aggregation pheromones. Canadian-Journal-of-Forest-Research
24(11): 2184-2190.
Keywords: tree/stand protection
tree/stand health
Abstract: A combination of antiaggregation and aggregation pheromones were tested for
protecting stands of Douglas fir (Pseudotsuga menziesii) at high risk for infestation by Douglas
fir beetle (Dendroctonus pseudotsugae) at a site in Oregon. The antiaggregation pheromone, 3methylcyclohex-2-en-1-one
(MCH), was applied in a bubble capsule formulation to the perimeter
of 1 ha circular plots at a rate of 60 g/plot. Treated plots also had three or four clusters of four
Lindgren funnel traps baited with frontalin, seudenol, 1-methylcyclohex-2-en-1-ol, and ethanol
located outside of the plot, but within 160 m of the boundary. Mean (+SD) accumulated catches
in all traps per plot were 73 658 + 19 721 Douglas fir beetles and 12 892 + 2513 Thanasimus
undatulus, a predator of the Douglas fir beetle. The mean percentage of Douglas fir trees with a
diameter at breast height (d.b.h.) 20 cm that were mass attacked was reduced by 80%
within the treated plots compared with the untreated plots. However, there was an 8-fold increase
in the percentage of trees mass attacked in the area outside the treated plots in the vicinity of the
funnel traps. The net effect of the treatment was to concentrate mass attacked trees within a
limited area outside of the protected stand. The results indicated that Douglas fir beetle
antiaggregation and aggregation pheromones can be used effectively to reduce the probability of
infestation in small, high value stands.
519. Ross, D.W., G.E. Daterman and K.E. Gibson. 2002. Elution rate and spacing of antiaggregation
pheromone dispensers for protecting live trees from Dendroctonus pseudotsugae (Coleoptera:
Scolytidae). Journal-of-Economic-Entomology 95(4): 778-781.
Keywords: tree/stand protection
tree/stand health
Abstract: The antiaggregation pheromone 3-methylcyclohex-2-en-1-one (MCH) is highly
effective in preventing the infestation of high-risk trees by Douglas-fir beetle, Dendroctonus
pseudotsugae. A large portion of the cost of an MCH treatment is related to the time applicators
spend walking through an area dispersing the formulated pheromone. Application of fewer MCH
dispensers eluting at a higher rate than those currently registered for operational use could
potentially reduce treatment costs. Two higher elution rates, 6 and 18 mg/d per dispenser, were
compared with the current standard of 2 mg/d per dispenser and an untreated control on 1-ha
circular plots. Dispensers were spaced 5, 15, and 44 m apart around the plot perimeters eluting 2,
6, and 18 mg/d, respectively. The nominal dose of MCH was 144 mg ha-1 d-1 on all plots.