Armillaria Root Rot
From Bugwoodwiki
Contents |
Importance
Armillaria root rot is one of the most common and damaging diseases of many hardwood forest and shade trees in North America. However, it occurs less often on sycamores than on other hardwood species.
Identifying the Disease
Trees exhibit a loss of vigor and gradual decline, yellowing of foliage, growth reductions, premature leaf drop, and branch dieback. In severe cases, and, given enough time, A. tabescens can kill a tree.
|
| Figure 33a. - Mushrooms of Armillaria tabescens. |
Identifying the Fungus
Following rains, clusters of A. tabescens may form at the base of diseased trees or from their roots. The mushroom is honey colored to brown, with white gills and a round cap that is 4 to 15 cm in diameter (fig. 33a). White, perforated fungal mats that form beneath the bark at the root collar, or on roots, are diagnostic (fig. 33b).
|
| Figure 33b. - Mycelial mats of Armillaria tabescens. |
Biology
The fungus survives as mycelium in the roots and stumps of dead trees from which it spreads to adjacent trees. Trees weakened by mechanical wounding or stressed by other pests are more susceptible to attack.
References
Leininger, T.D; Solomon, J.D.; Wilson, A. Dan; Schiff, N.M. 1999. A Guide to Major Insects, Diseases, Air Pollution Injury, and Chemical Injury of Sycamore. Gen. Tech. Rep. SRS-28. Asheville, NC: USDA Forest Service, Southern Research Station. 44 p.
