Dry conditions leave trees stressed and vulnerable

Monitor trees regularly for boring insects and bark beetles, says provincial woodlot specialist


Recent dry conditions will take a toll on trees, says the province’s woodlot extension specialist.

“It’s an invitation for insect infestations, not just for this year, but for upcoming years as well,” said Toso Bozic.

This is because stressed trees are less able to resist invasion, and some boring insects and bark beetles increase during dry periods.

There are a few different types of insects to keep an eye out for, he said.

“The yellow-headed spruce sawfly has been a problem for spruce the last few years, as well as spider mites. White pine weevil has also been a problem for young spruce trees as they target the leader (the top branch). Poplar and willow tree borer has been very dominant, along with a large infestation of forest tent caterpillar in the northern part of the province.”

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Sawfly larvae can be removed by hand and squished, whereas mites can be controlled with high-pressure soapy water, or by encouraging beneficial insects such as lady beetles. Young willow trees infected by willow borer can be cut to the base of the tree. Regrettably, there is very little that can be done with large aspen trees infected by poplar borer.

Besides insects and diseases, other factors can potentially contribute to declining or dying trees including improper use of chemicals, salt along roads, age of the trees, soil type, wildlife damage, competition, and heavy grazing. Bozic recommends only using insecticides as a last-ditch effort to control problems with insects.

But monitoring is key.

“From mid-May until Oct. 1, landowners should check their trees weekly to see what is going on,” said Bozic. “Monitoring also helps them keep on top of which trees may need watering under dry conditions, or may need help with other issues.”

If monitoring turns up insects, disease, or any other issues contributing to tree weakening, take a picture.

“Email a photo to me ([email protected]) so we can discuss what you’ve found. Please also provide photos from the surrounding area to help me determine the extent of the problem, as well as if other issues are at hand.”

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