Top Rots
From Bugwoodwiki
Contents |
Importance
Top rots result from invasion of limbs by many of the same fungi that cause butt rots. The incidence of top rot is typically lower than that of butt rot. Top rot often follows limb damage by ice or snow. Decaying limbs and tops may break, creating a hazard to people and property in urban areas. Losses of wood volume are usually insignificant.
Identifying the Disease
Broken or decayed limbs and branch scars often indicate top rot. The vertical extent of decay behind young or small branch scars is typically insignificant, but may extend into the bole and exceed 1 m behind old, larger branch scars.
Identifying the Fungi
Fruiting bodies can be used to identify these fungi, but they may not always be present. Identification by cultural characteristics instead of from fruiting bodies has been used with limited success because of the difficulty in isolating these fungi from the wood.
Biology
The life cycles of decay fungi causing top rots are similar to those of fungi causing butt rots. However, different pioneer micro-organisms are usually associated with the decay process in limbs than in trunks. Basidiospores are often disseminated from conks on hardwood species other than ashes. The spores produce hyphae that infect branch stubs, wounds, and scars, initiating decay
Control
Recognizing top decay and early harvesting of infected trees are useful means of reducing losses. Minimizing logging injuries can help reduce top rot in growing stock. Management alternatives should favor good growth to reduce the prospect of infection. Forest stands should be managed with proper stocking to reduce storm damage
References
Solomon, J.D.; Leininger, T.D.; Wilson, A.D.; Anderson, R.L.; Thompson, L.C.; McCracken, F.I. 1993. Ash pests: A guide to major insects, diseases, air pollution injury and chemical injury. Gen. Tech. Rep. SO-96. New Orleans, LA: U.S. Department of Agriculture, Forest Service, Southern Forest Experiment Station. 45 p.
