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Trees - Oak tree dying
Expert: Jim Hyland - 8/10/2008
Question
I reside in central Texas. The oak tree in my front yard is dying. The bark, especially at the base of the tree is black and flaking off. The leaves have turned brown in the last 3 weeks. The plants around the dying tree are all healthy. I'm not sure to the exact age of the tree. We bought our home new a year ago. The other oak on the other side of the yard seems to be healthy. Do you think it can be saved or do we need to cut it down.
Answer
Sounds like it maybe hypoxylon canker. IF so it more than likley will kill the tree. If the leaves are falling off completely the tree is dead. If they are turning and staying on the tree the tree is still alive and needs water. Place a pan under the tree and turn the sprinkler on and when the pan has 1 inch of water in it stop. I would water every fourth day unless it rains good.
Hypoxylon Canker has been noted in the death of many oaks in the East Texas area over the last several years. This disease is not rare, but due to the stressful droughts of the last several summers, a large number of trees are being affected.
The disease is first evident as a dieback of one or more branches. The foliage of the diseased limbs turns yellow and dries. This dieback continues from branch to branch through the stem until eventually the tree dies. This may require 1 or more years depending upon the environment and amount of stress experienced by the tree. Near death or shortly after tree death the outer bark sloughs off and exposes large masses of brown, dusty one-celled spores (conidia). These spores are gone within a few weeks and a grayish surface is visible. This is covered with numerous black fruiting structures. Mature fruiting structures (perithecia) can forcibly discharge sexual spores (ascospores) for distances of 60 mm. They are then blown to surrounding trees where infection occurs again. Entry appears to be through injured surfaces on limbs or trunk. The fungus grows best at 86 degrees F but can grow at 50 and 100 degrees F.
Hypoxylon canker causes a dark brown discoloration of the sapwood. With age the infected wood is lighter in color and has black zones or patterns in the wood when observed in cross section.
Hypoxylon canker occurs primarily on trees which are or have been in stressed conditions. Trees which have been damaged by excessive fill soil are often attacked by this organism. It is also suspected to be a fungus that can invade on oak wilt-infected trees.
Control is achieved by maintaining the trees in a healthy condition. Avoid injury to the trunk and limbs and never apply fill soil around the trees. Chemical treatments would not be effective because the fungus is located within the tree.
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