Gliocladium catenulatum as a Potential Biological Control Agent of Damping-off in Bedding Plants

Hyphal interactions between the antagonist Gliocladium catenulatum and the soil-borne plant pathogenic fungi, Pythium ultimum and Rhizoctonia solani, were investi- gated in dual culture by scanning electron microscopy. Gliocladium catenulatum hyphae grew along and some- times coiled loosely around those of the pathogens. Appressorium-like structures were produced by the antagonist which aided in holding and penetrating the hostsʹ hyphae. Partial destruction of these was observed in the later stages of parasitism. A wettable powder formulation of the antagonist was then evaluated for biological control of damping-o€ in bedding plant seedlings grown in a peat-based growing medium, arti®cially infested with P. ultimum or R. solani. A growing medium incorporation or drench of the formu- lation were, in general, equally e€ective in reducing damping-o€ and, in most cases, as e€ective as fungicide drenches of propamocarb HCl or tolclofos-methyl. Populations of G. catenulatum survived well in the pathogen-infested growing medium with levels of >106 colony forming units/cm3 being detected 28 days after application. Survival of G. catenulatum in the formula- tion and subsequent ability to reduce damping-o€ was una€ected by storage for 48 weeks at £ 5°C. Further, agar tests with fungicides showed that furalaxyl, prop- amocarb HCl and fosetyl-aluminium were minimally detrimental to the growth of the antagonist. The commercial implications of the results are discussed.