Three Things You Need To Know About Black Knot Fungus

Black knot fungus is a disease that can affect trees within the Prunus genus. Trees in this genus include trees that produce stone fruits, like cherry trees or peach trees. This disease can destroy not only your backyard fruit crop but your trees themselves; here are three things you need to know about black knot fungus.

What are the signs of black knot fungus?

At first, trees with black knot fungus have small lumps on their branches that are an olive-green color. Later, you will see that there are black, lumpy growths on the affected branches. The affected branches may crack or break due to the growths.

Why is black knot fungus a concern?

Black knot fungus makes your trees look very unattractive, a concern for any homeowner who is worried about their property value. However, unattractiveness is not the only problem caused by black knot fungus.

Like other fungal diseases, black knot fungus can girdle—grow all the way around—the affected branches, which kills them. This happens because the fungus cuts off the flow of water and vital nutrients to the branch. When the branches die, delicious fruits will no longer grow on them, and if enough branches die, your entire tree can succumb to the fungus.

What can you do about black knot fungus?

As soon as you see the signs of black knot fungus, you need to prune the infected branches. This helps to keep the fungus from spreading to other branches of the tree. It's important to clean your pruning shears with a bleach solution before moving to a new branch to avoid spreading the disease and making the problem worse. It's also important to clean the shears before you store them so that you don't infect other trees later in the season.

If you prune more than one-fifth of a tree's foliage, it may not be able to make the food it needs to survive or even to support itself structurally. If your tree is severely affected by black knot fungus and you'll need to remove more than one-fifth of the foliage, try treating the tree with fungicide spray, instead. This should be sprayed starting in the early spring and then continuing throughout the summer.

If your tree dies due to the fungal disease, it will need to be cut down. The tree service will need to safely dispose of the wood to keep the disease from spreading; it will either be taken to a land fill or burned, depending on the regulations in your area.

Black knot fungus can pose major problems for your prized fruit trees, so contact a tree service as soon as possible. To learn more, contact a tree trimming company like Sierra Mountain Tree Service.