There is the correlation between the mode of dissemination of the fungus and its relation to the host. In general leaf, stem, and fruit diseases are caused by airborne or insect-carried fungi, root diseases by soil inhabiting species. Some vascular wilts are caused by soil fungi, some by fungi possessing insect vectors.
Certain fungi are strictly local in their effect, producing lesions on leaf, stem or root system, though their localism may at times be an expression of host resistance. Other fungi are selective with respect to particular tissues, as exemplified by the vascular wilt organisms, which are confined to the water-conducting tissues; or the chestnut blight fungus, injuring the cambium layer. Still others are indiscriminate, establishing themselves at various points, and at times destroying the entire plant.