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Home → Publications → American Chestnut Proceedings → 1982 → Host-Parasite Interactions of Endothia Parasitica on Chestnut Species: State of the Art

Host-Parasite Interactions of Endothia Parasitica on Chestnut Species: State of the Art

ABSTRACT.--Cankers incited by Endothia parasitica on American, European, Japanese and Chinese chestnut trees have been described for various parts of the world and may be classified into four general types: A) sunken, B) irregularly swollen, C) callused and swollen ((i) with and (ii) without necrosis of the callus bark tissue), and D) superficial and swollen. Intermediate forms among A to D have been described and more than one canker type may be observed on the same tree. Canker types Cii or D have been associated commonly with virulent E. parasitica on Chinese and Japanese chestnut trees and hypovirulent E. parasitica on American and European chestnut trees, whereas canker types A, B or Ci are commonly associated with virulent E. parasitica on American, European and sometimes on Japanese and Chinese chestnut trees. Environmental factors (cold injury, frost injury, low soil fertility, shading or competition, and low soil water potential) that stress the host appear to play central roles in increasing the development of virulent E. parasitica on the normally blight-resistant Oriental chestnut species. The extent and nature of wound periderm formation appear to be important factors limiting E. parasitica infections in canker types Cii and D, but wound periderm appears to be ineffective, in most instances, in canker types A, B and Ci, due to a rapid growth rate of mycelial fans of the pathogen in bark tissues. In American and European chestnut trees, wound periderm may not be formed or is often not fully formed when the virulent pathogen invades this and neighboring tissues. Tannins (especially hamamelitannin in Castanea dentata and C. sativa), carbohydrates and amino acids in bark tissues appear to be key energy, carbon and nitrogen sources supporting rapid E. parasitica mycelial fan growth. The mechanical forces exerted by the mycelial fan,oxalic acid toxicity, acidification of host tissues (partly through the production of oxalic acid), and hydrolytic enzymes may play important roles in pathogenesis by E. parasitica.


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Author(s): Gary J. Griffin, John Rush Elkins, Frederick V. Hebard

Publication: American Chestnut Proceedings - 1982