Black Knot creating black eye

Town of High Prairie employee Kerry Gordey shows Black Knot that has infected Schubert chokecherry and mayday trees in the town.
Town of High Prairie employee Kerry Gordey shows Black Knot that has infected Schubert chokecherry and mayday trees in the town.

Richard Froese
South Peace News

Dozens of trees in High Prairie have been nailed with Black Knot.

Schubert chokecherry and mayday trees have been hit by the common disease caused by fungus, says Kerry Gordey, a Town of High Prairie employee, with a role to assist the town with tree issues.

“I have noticed that the majority of trees the town gave to owners of newly-built homes several years ago have been infected with Black Knot,” Gordey says.

“About 80 per cent of those types of trees in town have been infected.”

Most of the trees in the Silverwood Crescent area are those types of trees, he says.

Black Knot is known to grow with wet spring weather. No chemical controls will affect the disease.

“I first noticed it about seven years ago and it has spread,” Gordey says.
“It’s hard to detect in its early stages and it’s not until it matures and sets out spores that you can notice it.”
He says several people have already told him they have removed the diseased trees that were infected so extensively.
“I’m all for saving trees, but we as individuals and property owners need to manage them,” Gordey says.
“It’s all part of stewardship.”
Diseased trees on town property will be trimmed by municipal staff, he says.

“Some of the Black Knot is high in the canopy of the tree, so it’s difficult to get at to prune,” Gordey says.

While the disease has hit all parts of the province, he advises people to read information on suggested websites to make an informed decision to deal with the disease. They include:
– cityofgp.com
– 1.agric.gov.ab.ca
– treeexperts.mb.ca
– edmonton.ca

To control Black Knot, Gordey also provides published information that advises people to:
– Prune infected branches back to the next branch junction, at least 30 centimetres (12 inches).
– Burn infected material immediately or bag and dispose it in the landfill.
– Sterilize pruning tools between cuts as a precaution using gas line anti-freeze or a 10 per cent bleach solution.

A survey in Alberta revealed a significant and widespread distribution of Black Knot found in commercial, municipal, private and natural plantings, states information from the Alberta Agriculture and Forestry website.
This disease reduces the aesthetic value of affected specimens, as infections spread rapidly. High levels may result in the eventual death of the plant.

The most distinguishing symptom of Black Knot is the characteristic black, tar-like swellings that develops on branches of the infected plant. Swelling will grow until it is mature after 2-3 years.

Mature galls are hard, black, 10 to 15 cm (four to six inches) and may be somewhat ruptured.

Mature galls will produce and release a vast amount of spores during the bloom period, resulting in a rapid increase in infections.

Fungus continues to grow internally and externally, with the branch eventually dying.

 

Black Knot can first be noticed with a swollen branch that becomes a thick, unsightly black tar-like substance.
Black Knot can first be noticed with a swollen branch that becomes a thick, unsightly black tar-like substance.

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