Oystershell scale spreading through Calgary hedges

The oystershell scale insect isspreading through cotoneaster a plant widely used in Calgary for hedges, shrubs and bushes.

"If you drive through Inglewood, virtually every hedge is dead," said Keegan Seward, owner of The Arborest Expert Tree Service.

He says the bug hasbeen infiltratingother riverside communities, such as Douglasdale and Riverbend, for the last five years but isramping up all over the city becauseof thewarm and dry spring.

"It's not naturally being slowed down by weather.Usually cold and rain will slow it down," he said.

Oystershell scale affects 120 species, many of which grown in Calgary such as lilacs, hawethorn, green ash andcrabapple trees.

Symptoms

If areas of your cotoneaster suddenly go brown, it may be infested with thetiny vampires.

"The bugs suck all the juices out of the plant," said Corinne Hannah,a horticulturalistat the Calgary Zoo.

"If you look on the branches closely, you'll see all these little bumps and ridges that look kind of like oyster shells. That's the armor that those little bugs hide underneath," said Hannah.

Treatment

If the oystershell scale has only hit a small area of your cotoneaster, Hannah says you can spot treat it with insecticidal soap.

But if it's really bad,you're going to have to mow that hedge down and spray the stumps.

Seward is not a fan of pesticides, but says ifyou don't bring in the "big guns"the oystershell scalewill justcrawl back up thenew growth.

He says now is the time to take action becausethe babies, called "crawlers," are about to hatch and have not developed their protective armor.

Calgary'shabitat management superintendent, Lincoln Julie, is aware of the problem and is "currently assessing city trees and developing a treatment plan."

Fire blight

"It's ugly. It's an oozing, ugly mess," said Hannah.

Fire blight is another disease thataffects cotoneaster hedgesand all plants in the rose family, but it's abacteria not a bug.

Seward says fire blight isnot as prevalent in Calgary right now asoystershell scale, but it'sstill a problem.

Aclassic sign of fire blight on cotoneaster is when the plant's branches and leaves die back.

Hannah says you can treat itby using 10 per cent bleach on pruners and cuttingthe hedge to 30 centimetres past the affected area.

"You're basically doing a little amputation and sterilizing your tools."

Fire blight isalso deemed a pest under Alberta's Agricultural Pest Act.According to the City of Calgary, homeowners are responsible for keeping it under controlon their own property.