Most of the Alternaria sp. are parasitic, causing leafspot
diseases. A. solani causes ‘‘early-blight’’ of potato
and other members of the Solanaceae. Several form
species are found as saprobes on dead and dying plant
parts in the soil, from which the conidia are picked up
by the wind, and they invade laboratories where they
are troublesome as contaminants of cultures (Alexopoulos
and Mims 1979).