What Is Leucostoma Canker – How To Treat Canker On Fruit Trees In The Garden

Image by Norm Wingard

By Mary H. Dyer, Master Naturalist and Master Gardener

Leucostoma canker is a destructive fungal disease that affects fruits such as:

Leucostoma canker of stone fruits can be deadly to young trees and significantly decreases health and productivity of older trees, with a slow decline that often results in the demise of the tree. The disease also affects several types of hardwood trees, including willow and aspen.

What is Leucostoma Canker?

Leucostoma canker affects the bark through various types of injuries, including winter damage, dead branches and improper pruning. Insects, such as peach tree borer, can also create wounds that are susceptible to infection.

The first sign of infection is a sunken, black or brownish-yellow appearance and a gummy substance that oozes through the damaged spot in spring.

Affected trees grow a ring-shaped callus around the damaged spot during summer, but the disease soon infects the tissues around the callus. Eventually, the damaged spot looks like rings around rings.

Leucostoma Canker Treatment

Many people want to know how to treat canker on fruit trees. Unfortunately, there are no effective chemical controls and fungicides for treating Leucostoma canker. There are, however, a number of steps you can take to keep your trees healthy.

Prune cankers after petals fall from the tree, as wounds heal more rapidly during this time. Make each cut at least 4 inches below the edge of the canker. Although it takes time, careful pruning is the best way of treating Leucostoma canker. Rake up infected debris and dispose of it carefully.

Never prune stone fruit trees in fall or early winter. Remove dead or dying trees to prevent spread of the disease.

Avoid fertilization in fall, as new, tender growth is more susceptible to infection. Instead, feed fruit trees in late winter or early spring.

Control pests, such as peach tree borer and oriental fruit moth, since their damage can provide an entryway for infection.

Keep your trees healthy by proper watering and fertilization. Ensure soil is well drained. Unhealthy or stressed trees are more susceptible to Leucostoma canker.

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