The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. The use of drain tubes is no longer recommended because the wet wood bacteria can move out into healthy tissue and decay fungi and insects may move into the tree. If this area exceeds 30 to 50 percent of the trunk circumference, the tree may not close the wound. Use a smooth, continuous cut, to expose an elliptical area of bare wood. In trees where oozing liquid has damaged the bark, the dead bark can be cut away to allow for drying and better wound closure. Recently transplanted trees may show symptoms of wetwood, especially in the cambial area, if not adequately established. Adequate water during the summer months decreases wetwood symptoms. Plant stress especially drought appears to favor disease development and appearance of symptoms. There are no chemical treatments effective for curing or preventing wetwood. Insect vectors do not appear to be involved.Ĭonditions Favoring and Management of Disease Bacteria are assumed to enter trees through roots and thus it is hard to prevent. Very little is known about the bacteria and other microorganisms associated with wetwood and their transmission to healthy trees. The wetwood also occurs in the cambium or just under the bark killing branches and stems of stressed cottonwoods and globe willows. The slime is toxic to cambial tissue so wounds can not close since the callus is killed. Warping, increased drying time, and some cracking and splitting problems occur in boards cut form wetwood. Abnormal color and moisture in wetwood cause lumber to be devalued. Wetwood is important in forest trees harvested for lumber. Symptoms of nutrient deficiency may appear due to poor water movement within affected trees. Foliage of severely affected trees sometimes wilts, and branches, sections of the trunk, or the entire tree may prematurely die. After colonization by various bacteria and yeasts, the liquid becomes slimy and is often called slime flux. As the liquid flows down the bark, vertical dark or light streaks remain. Wetwood is most easily recognized by the presence of a liquid that oozes from wounds, crotches, branch stubs, frost cracks, or other weak points in the wood or bark. Wetwood typically develops in the center of the tree but may be found in the cambial area of stressed cottonwoods and globe willows. Research using affected elms suggests that an association of bacterial species, and possibly yeasts, act together to produce the complex of symptoms observed. However, several species of bacteria in the genera Enterobacter, Klebsiella, and Pseudomonas, which are often associated with wetwood, are thought to be directly involved. The causal agents of bacterial wetwood have not been conclusively identified. The disease also affects apple, ash, beech, birch, cherry, fir, honeylocust, linden, maple, mountain ash, mulberry, oak, sycamore, pines, and plum.
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