Expert recommends screening to protect favourite tree

By Chuck PoulsenSunday, March 18, 2007, http://www.dailycourier.ca/article_1046.php

If you have one special pine tree you’d like to save — and a limited amount of money to spend on it — which of the three most common defence options is your best bet against the pine beetle? That question was put to Joan Westfall, a registered forestry consultant for the past 20 years, from Entopath in Kamloops. She said homeowners should consider using all three options: Verbenone pouches, carbaryl pesticide spray and fibreglass screens around the trunk, if the price of the combination isn’t too high.If money is a consideration, she said she is partial toward the screening, but carbaryl would be her choice if conditions weren’t right for screens.“If I had a tree I really loved and I could only use one (method), I guess I’d go for the screening,” she said. “The exception is that if you have branches low down. They have to be cut, and that weakens the tree.“If it has a lot of branches, I’d spray with the carbaryl.”

Verbenone pheromone pouches are designed to stop mountain pine beetles. Its manufacturer, Phero Tech, believes they will work on western beetles, too, but Westfall doesn’t think they are effective against massive attacks of either.“I definitely would not say Verbenone is a sure-fired solution,” said Westfall. “The tests we did with Verbenone and a couple of extra components to combat the western pine beetle seemed to work well at low population number.“But in Kamloops, half the trees treated with Verbenone got attacked. That was virtually no different than the ones that weren’t treated.“In Kamloops, a lot of people lost trees that were treated with Verbenone,” she said, “and we had a combination of mountain and western pine beetle.”

She said nothing is foolproof, including carbaryl.“There’s nothing out there that is a golden bullet,” she said.Even the screening on a branchless trunk is not a guarantee. If a tear develops or the caulking in the screen is not perfect, it can’t be guaranteed to work, she said.Westfall warned that carbaryl can hurt useful insects, too, so it must by applied carefully by a professional. If the pH level of the water isn’t right, that can also reduce effectiveness.“There are all kinds of tricky things with it,” she said.