What Is Gummosis: Tips On Gummosis Prevention And Treatment

Amber sap emerging from a tree trunk through the process of gummosis
(Image credit: Jiri Anderle)

What is gummosis? If you have stone fruit trees, you’ll need to learn what causes gummosis disease. You’ll also want to learn about how to treat gummosis.

What is Gummosis?

Gummosis is a nonspecific condition where sap leaks from a wound in the tree. It usually occurs when the tree has a perennial or bacterial canker or is attacked by the peach tree borer.

However, gummosis can also be caused by any wound to a stone fruit tree, including winter damage, disease damage, or damage from a gardening tool. If you see gummy sap leaking out of your peach, plum, cherry, or apricot tree, it is probably gummosis.

Gummosis Prevention

Once you understand what causes gummosis disease – wounds to the bark of a tree – you can begin to think of gummosis prevention. Any action you can take to prevent bark wounds will also assist with gummosis prevention.

For example, take care when you are weed whacking or mowing around the base of stone fruit trees. If you damage the bark, you may soon be seeking gummosis treatment.

Likewise, plant your fruit trees in the best possible sites to avoid winter damage. Be sure to select wind-protected sites with well-drained soils. Keeping your tree healthy will also limit borer insect attacks.

It’s important to select tree varieties that do well in your hardiness zone. Choose varieties that resist cankers as well. All varieties can get cankers, but some get them more easily than others.

Gummosis Treatment

If you find sap leaking from your fruit trees despite your best efforts at gummosis prevention, it’s time to learn how to treat gummosis. The earlier you catch the problem, the better chance you have to save the tree.

The first thing to do if your fruit tree shows signs of gummosis is to correct any drainage problems. Providing good drainage by amending the soil or transplanting is essential to its recovery.

Another step in gummosis treatment involves removing the diseased bark. If you want to know how to treat gummosis, remove the darkened area of bark from the tree, plus a strip of the healthy bark, until the wound is surrounded by a margin of healthy bark.

Once this is done, let the area dry. Keep checking the area and repeat the bark trimming if necessary. Systemic fungicides can prevent some types of gummosis.

Teo Spengler

Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.