This week we continue our oak tree diseases by discussing some minor illnesses such as canker rots, twig blight and rust. Canker rots are caused by the fungi Irpex mollis, Polyporus hispidus and Poria spiculosa. Infection by these organisms tends to cause circular cankers. They have a depressed center rather than a conk or a mushroom. Canker rots will often form after a limb has been damaged or broken off. The best way to reduce canker rots is to remove any dead limbs or stubs in a tree. Prevent wounds or injuries to your oak trees as well. This will help keep the infection at bay.
Rust is caused by the fungus Cronartium strobilinum. The telial stage of this disease only occurs on evergreen oaks. That’s why they are so closely associated with live oak tree diseases. Leaves infected with rust have yellow or orange pustules on the lower sides of the leaves. Severe infection can cause defoliation of the tree. This would usually occur in the late spring or the early summer if it does happen. The disease cycle is broken if the host is removed. Unfortunately, the spores can drift long distances between oaks and pines. There is usually no way to control this so no special action needs to be taken on the tree care front. If it happens, we can remove the host and hope that no further damage is done. Remember – we don’t diagnose tree diseases. However, if you notice one of those problems, we suggest you call us. We can try to restore the health of your tree by trimming it or taking some other corrective action. We can be reached at 512-341-8888.
Twig Blight may be the one you’ve heard the most about. Caused by the fungus Physalaspora glandicola, twig blight can make affected trees look like they’ve been attached by cicada. You’ll often find dead shoots with attached brown leaves on the tree. We’re not going to deny that it can cause damage to the tree. However, it rarely kills a tree. The fungus overwinters in cankers on twigs. Infected limbs should be removed and burned or destroyed during the summer. It’s suggested to make cuts 6 inches below the diseased area to be safe. Fertilization, watering and pruning should be practiced to encourage tree vigor. A healthy tree will not become susceptible to this oak tree disease.
As you can see oak tree diseases can be slight or significant. Regardless, we can handle them if you have them. Contact us for more information if you suspect your tree is suffering from an oak tree disease.