What is Hypoxylon Canker and How To Treat It?

Date April 28, 2023

Author TreeNewal Staff

Property and home owners with oak and other hardwood trees may be affected by hypoxylon canker, a fungal infection that discolors and kills trees. Hypoxylon canker especially affects the East Texas region, which provides an excellent environment for the fungus to live, grow, and spread. Learning about the signs of this infection can help property owners protect their trees.

Image via Unsplash by niko_photos

What Is Hypoxylon Canker?

A hypoxylon canker is a lesion that appears on trees with the hypoxylon fungal disease. The cankers that form look smooth, but are not visible until the bark sloughs off the trunk or branches. The cankers will change colors from greenish-gray, to light gray, and finally to black as they go through the life cycle. This typically affects oak trees and other hardwood trees. It isn’t an aggressive pathogen and only affects weak or damaged trees. The hypoxlyon canker infection is most common in East Texas and the southern United States. Trees at most risk are oak trees weakened by defoliation, saturated soil, overcrowding, excavation near roots, herbicides, or drought.

Symptoms of a Hypoxylon Canker

Hypoxylon canker can kill infected trees quickly once the cankers appear on the main trunk, so it’s important for people to recognize the symptoms of this fungal infection. Here are signs property owners with hardwood trees can watch for:

  • Smaller leaves of some branches.
  • Leaves that turn yellow.
  • Dead leaves that still cling to the branches.
  • Discolored bark in a round or oval shape.
  • Cankers at wounds and unions of tree branches.
  • Yellow or orangish bark at the edges of a canker.

How Does Hypoxylon Canker Spread?

The hypoxylon fungus survives in tree cankers if not pruned out. After three years, the spores in the fungus are mature enough to be released. This fungus prefers damp weather, and the spores often spread after rain. Spores can’t infect a healthy tree, but if they land on a damaged tree they can infect it after a period of damp weather for 48 hours and in temperatures 60 degrees or higher. This fungus spread through the wood then moves through the bark, killing all healthy tree tissue.

What North Texas Trees Does This Effect?

The hypoxylon canker infection grows on weak oak trees and other hardwood trees, including:

  • Red oak.
  • Mexican oak.
  • Live oak.
  • Chinkapin oak.
  • Bur oak.
  • Lacey oak.
  • Elm.
  • Aspen.
  • Poplar.
  • Willow.
  • Pecan.
  • Hickory.
  • Sycamore.
  • Maple.
  • Beech.
  • Yaupon.

How to Treat a Hypoxylon Canker

Unfortunately, there isn’t a fungicide to prevent or cure this infection. Pruning infected branches during the dry season can keep the infection from reaching the trunk and extend the tree’s life. If property owners notice infected trees in the area, it’s important not to plant oak or other susceptible trees nearby.

By maintaining tree health, home and property owners can take precautions against trees becoming infected. Proper soil drainage and tree nutrition are key to keeping healthy trees. Avoiding root damage can also protect trees from becoming weak and vulnerable to this fungal infection. Property owners with oak trees can also regularly trim and prune them to promote health and growth.

TreeNewal is a certified arborist tree service that can assist and advise home and property owners on how to best care for their hardwood trees. For help in recognizing and treating hypoxylon canker, they can call a specialist and talk about tailored solutions.