Defoliator Management Guidebook

October 1995

Authority

Forest Practices Code of British Columbia Act

Operational Planning Regulation

Silviculture Practices Regulation

Introduction

Biology and identification

Distribution of major defoliators

Management principles for defoliators

Landscape and stand level hazard and risk assessment

Tree and stand impact

Detection and predictive sampling

Detection

Aerial surveys

Walkthroughs

Predictive and population sampling

Predictive sampling

Population sampling

Management strategies and treatment options

Douglas-fir tussock moth

Population dynamics

Predictive sampling techniques and population monitoring

Long-term strategies

Short-term strategies

Virus (NPV) application

Western spruce budworm

Population dynamics

Predictive sampling techniques and population monitoring

Long-term strategies

Short-term strategies: biological and chemical control

Western hemlock looper

Population dynamics and detection

Predictive sampling techniques

Long-term strategies

Short-term strategies

Eastern spruce budworm

Population dynamics

Population monitoring and predictive sampling techniques

Long-term strategies

Western blackheaded budworm

Population dynamics and impact

Detection, population monitoring, and predictive sampling

Long-term strategies

Short-term strategies

Glossary

References

General

Douglas-fir tussock moth

Western spruce budworm

Western hemlock looper

Eastern spruce budworm

Western blackheaded budworm

Tables

1. Common forest insect defoliators and their hosts in B.C.
2. Occurrence of life stages of insect defoliators
3. Description and illustration of life stages of five defoliating insects
4. Detection criteria and symptoms for the major defoliators at stand and tree level
5. Defoliation intensity ratings for aerial survey mapping
6. Recommended and possible time frames for predictive and population sampling of the five defoliators
7. Comparison between foliage protection and population reduction strategies for direct control of forest defoliators
8. Pre-harvest and post-harvest prescription strategies and treatments
9. Parameters influencing hazard for Douglas-fir tussock moth
10. Preferred treatment options for the Douglas-fir tussock moth at different stages in its outbreak cycle.
11. The schedule of events to detect, monitor, and manage Douglas-fir tussock moth
12. Product information on registered virus formulations available for use on the Douglas-fir tussock moth
13. Parameters influencing hazard for western spruce budworm
14. Average percent loss in the first decade of a 20-year projection in total volume (volume of all trees, between stump and 10 cm top diameter) and harvest volume (volume of logs from trees with a dbh of 30 cm or greater) in interior B.C. after a simulated 7-year western spruce budworm infestation
15. Description of larval instars of the western spruce budworm
16. Application specifications and timing for B.t.k application
17. Recommended number of sample trees needed to determine spray efficacy in a range of block sizes
18. The schedule of events to detect, monitor, and manage western spruce budworm
19. Parameters influencing hazard for western hemlock looper
20. Parameters influencing hazard for eastern spruce budworm
21. Interpretation of eastern spruce budworm current defoliation
22. Old defoliation/damage rating for the eastern spruce budworm
23. Tree vigor rating based on occular assessment for eastern spruce budworm
24. Interpretation of eastern spruce budworm egg mass densities
25. Calculation of total rating factor for eastern spruce budworm
26. Parameters influencing hazard for western blackheaded budworm
27. Predicted defoliation levels for the western blackheaded budworm based on the numbers of eggs per branch

Figures

1. Douglas-fir tussock moth defoliation history for B.C. 1916–1994
2. Western spruce budworm risk analysis for B.C. 1909–1992
3. Western hemlock looper frequency analysis for B.C. 1911–1994
4. Eastern spruce budworm history for B.C. 1956–1994
5. Blackheaded budworm defoliation history for B.C. 1916–1994
6. Defoliator management process
7. Whole tree defoliation classes by percent crown totally defoliated, with inset showing close-up of branch tip
8. Fettes scale of defoliation for current year foliage
9. Illustration of the relative abundance of insects during the four phases of a defoliator cycle
10. Douglas-fir tussock moth egg mass survey tally card with an example of a sequential survey and calculations
11. Western spruce budworm egg mass sampling field form
12. Western spruce budworm larval sampling field form
13. Application of the population reduction and foliage protection strategies given the prediction of high budworm population levels in the coming year
14. Decision-making process in multi-layered stands for doing predictive sampling surveys
15. Decision-making process for treatments in a multi-layered stand with only current year defoliation
16. Decision-making process for treatments in a multi-layered stand with 2 years defoliation
17. Decision-making process for treatments in a multi-layered stand with >2 years defoliation
18. Criteria for treatment of eastern spruce budworm