black knot fungus Black knot disease is a warty, black mass that appears on trees. It can be anywhere from an inch to a foot long. If the mass is older, it can take on a pinkish undertone caused by mold.

It is most common in cherry and plum trees, but other fruit trees can also be infected.

How Black Knot Fungus Spreads

On rainy spring days, black knot fungus releases spores that travel on wind currents. If the spore lands on your cherry or plum tree, the spores can germinate, infecting the tree.

The hollow areas created by the black knot create a good habitat for insects and other pests, so you will want to avoid black fungus at all costs.

How to Get Rid of Black Knot Fungus

A common way to treat black knot fungus is by spraying with fungicide, however, there is some debate over whether this is effective.

The best way to treat black knot fungus is by pruning away the affected parts of the tree. Since the fungus tends to burrow deep in the tree, this can be tricky, so treating black knot fungus is a task best left to the professionals.

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