Tree Disease Concepts

agent amount appears areas associated avoid bacteria bark become blight branches brown called canker caused cell changes Chapter characteristic chemical common concept Conidiophores crops culture cycle dead decay fungi decline discussed disease effects example factors FIGURE foliage diseases forest fruit bodies fungus future genetic growing growth hardwoods heart rot host hyphae important increase infection invasion involves leaves limited living losses major maple method moisture mycelium mycorrhizae natural nematodes nursery oak wilt occur organisms parasitic pathogen pathologists pathology period pine plant pollution population practices present problems produce recognize reduced resistance result role root rot rot fungi rust seed seedlings selection serious Serv soil species spores spread stage stain stand stem structures surface symptoms temperature tion tissue trees USDA usually utilize virus viruses wall wilt wood wounds York