Canadian Forest Service Publications

Development of a biological control strategy to mitigate hemlock dwarf mistletoe in silviculture systems: Neonectria neomacrospora hemlock dwarf mistletoe pathosystem. 2006. Reitman, L.M.; Shamoun, S.F.; van der Kamp, B.J. BC Journal of Ecosystems and Management 7(1): 30-35.

Year: 2006

Issued by: Pacific Forestry Centre

Catalog ID: 26098

Language: English

Availability: Not available through the CFS (click for more information).

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The current demand for non-clearcutting forestry practices is expected to result in substantially increased hemlock dwarf mistletoe infection because a much larger proportion of regenerating trees will be within the range of mistletoe seed dispersal from infected residual trees. Consequently, it has become necessary to develop alternative methods for its control. In this study, we investigated the effectiveness of Neonectria neomacrospora as an inundative biological control agent for hemlock dwarf mistletoe. Specifically, we determined whether wounding facilitates infection of mistletoe swellings by N. neomacrospora and measured the effect that successful infection had on dwarf mistletoe shoot production. Based on our results, the wounded, inoculated treatment had the greatest effect on N. neomacrospora infection. These findings do not concur with the inoculation study by Funk et al. (1973), perhaps because of the different time frames of the two studies. Although the extent of bark necrosis for the unwounded, inoculated treatment was not huge, the treatment had 39% more N. neomacrospora re-isolation success than its respective control. Although all dwarf mistletoe swellings lost shoots over the trial period, the confirmed group lost significantly more than the unconfirmed group (p = 0.025). In addition, more swellings from the confirmed group did not have shoots. Overall, infection of hemlock dwarf mistletoe by N. neomacrospora reduced the number of healthy shoots by 38%. This extended abstract presents a summary of the study results and its implications, and suggests some future research needs.