Mycoparasitism of Alternaria alternata by an Additional Eight Fungi Indicating the Existence of Further Unknown Candidates for Biological Control

In studies using light and scanning electron microscopy it was clearly demonstrated that Nectria inventa, Gliocladium roseum, G. ca.tenula.tum, Clonostacbys sp., Sesquidllium sp., Verticillium nigrescens, Dicyma olivacea, Stachybotrys elegans, Myrothecium carmichaelii, M. cinctum, M. roridum, M. tongaense, M. verrucaria and Coniothyrium sporulosum are able to parasitize Alternaria alternata. With the exception of N. inventa and the five Myrothecium spp., none of the other fungi has been previously reported to be mycoparasitic on Alternaria. Moreover, there is no current information about the mycoparasitic and antibiotic activity of the genera Clonostacbys and Sesquici-lium. The mode of parasitism was nearly the same in all of the mycoparasites. In many cases, penetration was achieved directly by the hyphal tips without the formation of appressorium like structures (ALS) and there was no evidence that the formation of ALS was a prerequisite for penetration. Dependant on the severity of infection, a gradual shrinkage, distortion and an eventual collapse of the parasitized conidia were observed. A bursting and total collapse of the spores without any penetration was detected by the antibiotic producing mycoparasites such as G. roseum, G. CAtenulatum, Clonostacbys sp., Sesquicillium sp., D. olivacea and the five Myrothecium species. In consideration of their activity, all of the tested antagonists would appear to be candidates for in vivo investigations to check their suitability as biocontrol agents. Copyright © 1993, Wiley Blackwell. All rights reserve