Disease Suppression and Growth Promotion in Douglas-fir Seedlings by the Ectomycorrhizal Fungus Laccaria laccata
Abstract:In pot tests, primary roots of Douglas-fir seedlings germinating in soil were inoculated by soil injection with suspensions of Laccaria laccata and (or) Trichoderma sp., or Pseudomonas cepacia, or were treated with benomyl fungicide applied as soil drenches. The root pathogen Fusarium oxysporum was introduced 7-10 days after these treatments. All three organisms and the fungicide suppressed disease. L. laccata protected as well as the fungicidal drenches and better than the nonmycorrhizal biocontrol agents. The protected seedlings, in comparison to those exposed only to the pathogen, had fewer root lesions, yielded fewer colonies of F. oxysporum in isolations from roots, had longer roots at 8 wk and greater heights and weights at 14-20 wk. Only L. laccata prevented needle curling, a nonspecific symptom of stress in Douglas-fir seedlings. In the absence of F. oxysporum, L. laccata caused dry weight increase up to 55 percent greater than that of nonmycorrhizal plants after 12 wk. Where the pathogen was present, L. laccata caused weight increase 24 percent greater than that of benomyl treated plants and 102 percent greater than untreated plants after 14 wk. Top/root ratios indicated selective stimulation of top growth by the mycorrhizal fungus concomitant with the formation of ectomycorrhizae. Forest Sci. 28:191-201.
Document Type: Journal Article
Affiliations: Research Support Specialist, Department of Plant Pathology, Cornell University, Ithaca, NY 14853
Publication date: 1982-06-01
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- Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.
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