Black knot tree fungus erupts in Edmonton

A deadly tree fungus is spreadingacrossEdmonton, and gardening experts say the sooner its dealt with, the better.

Rob Sproule, owner ofSalisbury Greenhouse gardening centre, says the fungus is called "black knot" and it can kill a tree in just a few years if you don't take action.

The fungus causesirregular swelling on a tree's branches. At first, the swellingis olive green, like new wood, but it then turns black and hard, and begins strangling the affected branch.

Sproule said the infection is easy to spot.

"Just look out into yourtrees and look for the silhouette, the thickened black, it almost looks like charred black rope is wrapped around it or burnt sausage links, something like that," he said.

Sproule said catching the fungus early and pruning the infected branches can usually save the tree.

"If you get rid of all the knots, the tree should be fine,"he said.

But because the fungus spreads through spores, he said not to compost the branches. Instead, wrap them in plastic and throw them away inthe regular garbage.

Sproule also said one should disinfect or sanitize pruning shears between each cut in order to reduce the likelihood of spreading the spores to a new branch.

Black knot fungus targets mainly mayday and fruit trees, and has become a problem elsewhere in urbanCanada in recent years.

In 2012, the City of Winnipeg took agressive steps to slow the spread of the fungus in some of its newer neighbourhoods,removing around 800 city-planted chokecherry treesthat were infected.