. Recent research on conifer needle diseases : conference proceedings, October 14-18, 1984, Gulfport, Mississippi. Conifers Diseases and pests Congresses. Figure 1. Lophodermium ascospore germination types. Postpenetration.—Immediately after penetration differences between species were observed. With L. pinastri, the infecting hyphae were observed to form "bladderlike" hyphae in the cuticles but necrosis of the cells below was not observed (fig. 3). At this stage sectioning of needles inoculated with L. pinastri revealed no further growth of the fungus from the cuticular region and n
. Recent research on conifer needle diseases : conference proceedings, October 14-18, 1984, Gulfport, Mississippi. Conifers Diseases and pests Congresses. Figure 1. Lophodermium ascospore germination types. Postpenetration.—Immediately after penetration differences between species were observed. With L. pinastri, the infecting hyphae were observed to form "bladderlike" hyphae in the cuticles but necrosis of the cells below was not observed (fig. 3). At this stage sectioning of needles inoculated with L. pinastri revealed no further growth of the fungus from the cuticular region and no lesions were formed. Remnants of L. pinastri ascospores on the needle surface could not be located in week 14 after ascospore deposition and, as no microsymptoms of infection were visible, this made further sectioning of. Figure 2. Collapsed L. pinastri ascospore (ca) with an appressorium (a) on needle surface of Pinus sylvestris (x 1000). needles a fruitless task. However, observations of 2- to 3-mm diameter infection spots, on 2nd and 3rd year needles from 16-year-old trees, revealed that L. pinastri could be isolated from them, suggesting that further colonization of aging tissues by L. pinastri, resulting in the formation of the infection spots, does take place but is not extensive enough to cause macrosymptoms. With L. conigenum intracuticular hyphae were rare but, in most cases, bladderlike hyphae grew in the epidermal cells and further into the hypodermal cells through the plasmodesmata and formed "hyphal complexes" in the cell lumen (fig. 3). The complexes which are similar to those formed in germination type V became melanized both when formed on an inert surface and in the plant cells, which made it difficult to stain them. This may be the reason why Hartig (1882) found it difficult to detect the presence of Lophodermium in the early stages after the death of needles killed by Lophodermium. After the formation of complexes in the hypodermal cells no furt
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