What to Do With a Bleeding Tree: Gummosis

Peach Tree
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Bleeding bark on woody plants often leads to some concern when seen by tree growers and yard tree owners. Gum and sap draining from a tree trunk or limbs are very common in trees in the genus Prunus which includes peaches and cherries but can happen in many species. This sap flow can be caused by both biotic diseases and abiotic injury.

One textbook definition of the term gummosis is "the copious production and exudation of gum by a diseased or damaged tree, especially as a symptom of a disease of fruit trees." But It can also be an early symptom of problems, not only in orchards but in prized specimen landscape trees in yards, parks, and forests. 

Gummosis in a tree is not the end of the world. Any bleeding or oozing of sap from a tree, although not normal, will not necessarily permanently harm a tree or woody plant and they usually survive most sap bleeding instances. It is also important to remember that there are many causes for free-running sap from trees to include insect borers, cankers, bark injury and a variety of diseases. Controlling these damaging sources will control gum deposits and sap flow but there usually is no cure.

The Causes of Bleeding Trees or Gummosis

Gum exuding from cherries, peaches, and sweetgum is very common so keep an eye out for bleeding on these particular species. Gummosis is not actually a pathogen in itself but is the response to environmental stress from pathogenic injury, insect injury and mechanical injury where you will see excessive sap oozing.

Pathogenic infectious diseases and cankers that result in bleeding sap can become problematic in fruit orchards. Particularly, the cytospora canker or perennial canker is an important fungal cause of bleeding in stone fruited trees like apricot, cherry, peach, and plum.

This infection is distinguishable from insect damage and mechanical injuries because sawdust or pieces of bark are not mixed in the sap, as it would be with insect or mechanical damage. Cytospora canker is also known as perennial canker. It is not important for you to identify the specific cause(s) involved but very important to differentiate between insect infestation, mechanical injury, and infectious disease for diagnosis.

How to Prevent and Treat Tree Bleeding and Gum Flow

There are pest management practices you can follow that will lower the risk of gummosis. Be careful when using lawn and garden equipment to avoid tree tissue injury that can harbor fungal spores; prevent winter cold injury to your tree by planting cold-hardy species within its hardiness zone and out of isolated wind avenues; maintain a tree's health to discourage boring insects and prune and dispose of limbs during late winter.

Try to identify whether the tree has been injured mechanically, been attacked by insects or infected by a disease. Typically, mechanical injury and insects will leave exposed sapwood or sawdust.

Treat the causes as best you can while increasing the most "comfortable" tree conditions for optimal health. Increasing tree vigor is a must and will yield great results. One immediate suggested treatment might be the application of garden lime (several pints) under the tree drip-line if your site has a low to moderate PH. Raising soil Ph to 6.5 can do wonders for tree health.