Fungous diseases of plants . cient to warrant bringing together the related forms as one species is generallylacking. In the determination of a species too much dependence cannot be placedupon cultural characters alone. These characters are useful, but are not suffi-ciently constant to justify exclusive use. Thus far species of Gloeosporium seem to have been definitelyconnected with three genera of Ascomycetes, as follows : Pseudope-ziza, Glomerella, and Gno-monia, the imperfect stagesof which were respectivelyknown as GlaosporimnRibis (Lib.) Mont. &Desm., Glawsponmn fnic-tigcmim Berk., and Gl
Fungous diseases of plants . cient to warrant bringing together the related forms as one species is generallylacking. In the determination of a species too much dependence cannot be placedupon cultural characters alone. These characters are useful, but are not suffi-ciently constant to justify exclusive use. Thus far species of Gloeosporium seem to have been definitelyconnected with three genera of Ascomycetes, as follows : Pseudope-ziza, Glomerella, and Gno-monia, the imperfect stagesof which were respectivelyknown as GlaosporimnRibis (Lib.) Mont. &Desm., Glawsponmn fnic-tigcmim Berk., and Gloeo-sporhim nerviseqiunn imperfect form is in-variably the importantstage from the phytopatho-logical point of view. Theeffects upon the hosts arein every way comparableto those resulting from theattacks of various species placed in the closely related genus Colletotrichum previously de-scribed. In fact, some species of Gloeosporium occasionally pro-duce a small number of setae under special conditions. Upon the. Fig. 158. Glceosporium on Leaves ofNorway Maple 1 See Bitter Rot of the Apple, p. 271. 332 FUNGOUS DISEASES OF PLANTS twig cankers the gloeosporial stage of the apple bitter rot fungusmay produce these. Moreover, in artificial cultures species of Colle-totrichum have also yielded ascigerous stages referable to the genusGlomerella.^ On the other hand there is a fairly close relationshipbetween extreme forms of Colletotrichum and Volutella. In members of both Colletotrichum and Gloeosporium it has longbeen known that when conidia germinate in a drop of water on aglass slide, or under certain other conditions, structures resemblingsecondary or resting spores may be formed. Hasselbring^ hasmade a special study of these and concludes : The spore-like organs formed by the germ tubes of the anthracnoses areadhesion organs, by means of which the fungus is attached to the surface ofits host during the early stages of infection. They are not suited for dissemi-nation an
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