Anyone who has fruit trees in Alberta knows that they can be prone to disease unless carefully monitored and treated. One disease common to our area is black knot fungus. Take time to learn the facts about this tree disease so you can keep your arbor healthy and thriving.
What It Is
Black knot is caused by a fungus that often impacts a wide variety of the prune species, including plums, apricots, and cherries. It is also extremely aggressive on Shubert chokecherry and mayday trees in Alberta.
The last decade has seen a marked increase in infestations, such that more trees than before are showing significant problems.
What It Looks Like
Watch your trees between April and June, particularly during wet, warm weather. Here are a few common symptoms you may see:
By the time you see olive green knots, spore release is imminent. The fungus releases spores heavily during blossom time, just before trees begin to leaf.
After spore release, knots turn dark. By autumn they appear as black knots, hence their name. Knots will continue to grow until they surround a given branch and kill it. If the infestation spreads, it may eventually kill the tree itself.
How to Manage It
As with any tree disease, vigilance is key. Follow these 4 tips to gain the upper hand in disease prevention or containment: