Developing proactive forest management strategies to reduce the area of high-risk stands before the outbreak begins is important to mitigating damage from the spruce budworm and should be implemented as soon as possible before the outbreak begins. Effective monitoring is the first requirement in deciding when and where to harvest high-risk stands or prescribing insecticide applications to protect valuable stands that are not ready for harvesting. Monitoring is an effective early indicator of an imminent outbreak, which is closely correlated with the level of defoliation damage to fir and spruce. Intensive monitoring is central to implementing integrated pest management (IPM) strategies.
Early Intervention Strategy
Because of the ongoing SBW outbreak in Quebec that is now threatening the Atlantic Provinces, the Canadian government is supporting an early intervention strategy (EIS) to develop, test, and monitor the effectiveness of using B.t.K., tebufenozide, and SBW pheromone applications to minimize the coming SBW outbreak in Atlantic Canada. Their EIS strategy involves intensive monitoring and early detection of SBW in forest stands, target-specific insecticide applications to small, infested areas; and
using tools and techniques to disrupt SBW mating and migration in those areas to reduce or eliminate SBW development and spread.
It will be essential for CFRU, MFS, and MFPC to maintain close communications with researchers on this EIS project as it develops and tests effective approaches that show early promise for Maine’s forests.
The following forest management strategies are just a few that are recommended by the Spruce Budworm Task Force report for forest landowners to prepare for the coming SBW outbreak in order to assure a healthy forest and consistent wood supply (see the task force report for the complete list of recommendations):
- Map the location, condition, and concentration of high-risk stands on your forestlands.
- Shift harvesting now and in the coming years toward merchantable higher-risk stands and avoid harvesting in lower risk stands.
- Prepare action plans to salvage (or pre-salvage) trees that will likely be lost through SBW mortality.
- Seek and encourage markets for low-value trees from pre-salvage and salvage operations.
Although forest management strategies can substantially mitigate the effects of the coming SBW outbreak, those efforts alone will not adequately protect high-value stands from defoliation when SBW populations reach high levels. Foliage protection using aerially applied insecticides is available in these circumstances for direct protection of high-risk and high-value stands. There have been substantial technological advances in SBW insecticides in the 40 years since the last outbreak. Today, new insecticides (e.g., B.t.K. and tebufenozide) are available that have lower toxicity and affect a narrower range of non-target organisms, and are therefore more targeted in their environmental effects. In addition, application technology is now very precise and accurate satellite navigation systems on smaller aircraft are available for more targeted and smaller-scale applications, and the Maine Board of Pesticides Control provides guidance for application of pesticides. Furthermore, the latest wood supply model indicates that no more than 20% of the infested area would need to be treated with B.t. insecticide to achieve near maximum benefit. Therefore, Maine’s SBW insecticide treatment program during the coming outbreak will likely be much smaller than the one used during the 1970s–80s outbreak. Insecticide treatments are not anticipated to occur before 2017 in Maine since no SBW defoliation has been observed yet, with the possible exception of testing early intervention strategy treatments at limited locations.