title: Microcycle Conidiation and Spore-Carrying Capacity of Colletotrichum gloeosporioides on Solid Media.
abstract: The effect of spore inoculum density, medium concentration, and temperature on slime-spot formation, spore yield, and mycelium production by Colletotrichum gloeosporioides on agar media were studied with a simple microplate assay. A steady-state spore yield (spore-carrying capacity) independent of inoculum density was reached only on media that supported good fungal growth and sporulation. The spore-carrying capacity was reached earlier, the denser the inoculum. On standard mycological media a high inoculum density (2.5 x 10 spores per ml) resulted in a slimy mass of conidia forming a slime spot, a phenomenon associated with greatly reduced mycelium formation and indicative of microcycle conidiation. In contrast, for a similar inoculum density, enhanced mycelial growth preceded sporulation and overrode slime-spot formation on highly concentrated media; a very low medium concentration resulted in much less mycelium, but spore production was also decreased. Exposure to suboptimal growth temperatures of 36 to 48 degrees C for up to 8 days did not induce microcycle conidiation from inocula that did not form a slime spot at 28 degrees C.
authors.affiliation: Department of Plant Pathology and Department of Soil Science , University of Wisconsin-Madison, Madison, Wisconsin 53706.
authors.forename: S J
authors.initials: SJ
authors.lastname: Slade
authors.forename: R F
authors.initials: RF
authors.lastname: Harris
authors.forename: C S
authors.initials: CS
authors.lastname: Smith
authors.forename: J H
authors.initials: JH
authors.lastname: Andrews