City of Fort St. John warns of black knot fungus

FORT ST. JOHN, B.C. – Before their yard waste drop-off day on May 7th, the city of Fort St. John is warning the community about black knot fungus.

Black knot fungus-infected plants are not permitted to be dropped off during their Yard Waste Drop-Off events.

The city’s website has a page dedicated to black knot fungus, what it is, how to spot it, and how to treat it.

The city says black knot is a fungal disease that attacks explicitly plum and cherry trees.

According to the website, the fungus can be identified by hard, black and uneven swells that appear to wrap twigs and branches of the tree.

If the fungus remains untreated, it strangles the new growth. The city says that the tree will deteriorate, and the ‘galls’ produced also provide an in for other diseases and insect infestations.

The city says that it takes an entire season before it’s visually apparent and may even take up to a year to be spotted, as the galls start as small and light brown and/or olive green.

The website explains that the swelling becomes mature after two to three years, and at that point, it can be between ten and fifteen centimetres big and possibly somewhat ruptured.

Once matured, they produce and release a lot of spores during the bloom period (just before trees begin to leaf), increasing more infections, the website says.

The city provides tips to prevent and contain black knot, including inspecting the trees annually, removing infected branches at least six inches from the knot, and sanitizing tools.

The site mentions that experts can’t agree on the effectiveness of fungicides on black knot disease, but most warn against relying solely on them.

For more information and all of the tips, visit the city’s page on black knot.