Drought Stress And Hypoxylon Canker

As most San Antonio residents know, we have been under drought conditions for several years now. The result of this drought has taken an extreme toll on the trees here in Central Texas. There is a cumulative effect that begins to happen on our trees. Trees that are not drought tolerant at all begin to show the first signs of stress. This can include wilting leaves, drying  up of the leaves and sometimes die back of the branches. There are several trees that were being planted 10 years ago that arborists are not even recommending to plant any longer in this area due to the change in rainfall that we have experienced.

Hypoxylon Canker

Drought conditions can also cause something called hypoxylon. This can be recognized by brown or black patches under the bark that looks unusual. After hypoxylon has been present for some time, it will turn gray in color. Hypoxylon cankers happen when the drying out of the nutrient layers is so extreme that it makes conditions right for the tree to become infected with hypoxylon. If hypoxylon is in the main trunk of the tree, there is no cure and the tree is on its way out. If you see these patches in the limbs but not in the main trunk there is a chance of pruning the infected limbs and salvaging the tree. Only time will tell if the pruning will have saved the tree however. Certain species are more likely to contract the hypoxylon cankers. Species very prone to getting it are pecans, maples, certain oaks and more.

Preventing Hypoxylon

If your trees have been under drought stress there are a few things you can do.

1. Mulch up to 4 inches under the root zone of the tree. This will help hold in moisture, shade the roots and keep out competing weeds and grasses.

2. Deep water your trees 2 to 3 times a week in the summer. I am not talking about sprinklers here, you must have a slow trickle from the hose deep saturate under the root zone for 45 minutes or until water runoff begins to happen.

For more information on hypoxylon cankers or for a diagnosis contact our certified arborists today for a consultation.