White pine weevil management

• Weevil management 
• Sampling to assess weevil attack
• Hazard rating
• Silvicultural methods of control
• Better site selection
• Resistance to attack
• Fertilization and weevil attack

---

Resistance to attack

The ability of the tree to resist weevil attack can be measured by determining attack intensity among candidate genotypes and by measuring the tolerance of the tree to attack, i.e., the tree's ability to recover with no or minimum defect. In collaboration with the Ministry of Forests, a number of resistant provenances, families and individual trees have been identified in British Columbia. Mass propagation of these genotypes is being commercially developed by B.C. Research Inc. Similar screening studies are being conducted in Quebec.

Several host traits related to resistance are under study:

• Variation in chemical composition of feeding stimulants and deterrents in bark;
• Differences in resin canal density;
• Differences in the physical and chemical properties of resin;
• Production of traumatic resin;
• Ability of the tree to inhibit the reproductive physiology of the weevil (Leal et al. 1997, Trudel et al. 1998, Sahota et al. 1998).

These traits vary over the course of the season, with tree phenology (Hulme 1995), and over a range of sites. It is important to deploy the resistant trees as a mixture of genotypes. This will reduce the chances of the weevil adapting to resistant stock.

---