. Recent research on conifer needle diseases : conference proceedings, October 14-18, 1984, Gulfport, Mississippi. Conifers Diseases and pests Congresses. 10 weeks 12 weeks Colonisation is progressive into the stele and the needle dies. Figure 3. Postpenetration differences between Lophodermium infections. a = appressorium, b = bladder hyphae, he = hyphal complex, c = cuticle, e = epidermis, h = hypodermis, m = mesophyll. With L. seditiosum, the infecting hyphae first formed bladderlike hyphae in a single epidermal cell and then colonized the adjacent epidermal cells. Under a mic
. Recent research on conifer needle diseases : conference proceedings, October 14-18, 1984, Gulfport, Mississippi. Conifers Diseases and pests Congresses. 10 weeks 12 weeks Colonisation is progressive into the stele and the needle dies. Figure 3. Postpenetration differences between Lophodermium infections. a = appressorium, b = bladder hyphae, he = hyphal complex, c = cuticle, e = epidermis, h = hypodermis, m = mesophyll. With L. seditiosum, the infecting hyphae first formed bladderlike hyphae in a single epidermal cell and then colonized the adjacent epidermal cells. Under a microscope yellow spots could be observed in the same week that penetration had occurred. These microsymptoms could be used to distinguish which ascospore had infected and which one had not. The microsymptoms were composed of about 3-5 epidermal cells transversely and about two cells longitudinally. Where infecting ascospores were numerous, initial symptoms appeared as yellow flecks. These yellow spots or flecks could be observed by the unaided eye 7 weeks after inoculation but were very temporary and had turned brown a week later. At this stage, colonization was mainly of epidermal cells, with only a few hypodermal cells affected (figs. 3 and 4).. Figure 4. L. seditiosum normal hypha (n) in an epidermal cell and a 'hyphal complex' (he) in a hypodermal cell (x 1250). 25. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peterson, Glenn W; International Union of Forestry Research Organizations. Working Party on Needle Diseases. Washington, D. C. : U. S. Dept. of Agriculture, Forest Service
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