An Agar Disc Method for Isolation of Fungi Colonizing Nematode Eggs

Abstract

A method was developed for estimating the level of fungal colonization of nematode eggs in soil and for isolation of involved fungi. A 1.4-mm mesh fiberglass screen was glued between two 5.6-cm diam rings cut from polyvinyl chloride (PVC) pipe. Together, the rings formed a 1-cm long cylinder bearing a screen across its middle. The cylinder was filled with water agar bearing Meloidogyne arenaria eggs in suspension. Cylinders were buried singly in pots of soil treated with two levels of chitin (0 or 2% w/w) and 6 levels of sucrose (0 to 2%). After 10 days the rings were retrieved, and eggs in the agar were examined for fungal colonization. Eggs in discs buried in soil with chitin had higher rates of fungal invasion than eggs buried in soil with no chitin. Representative colonized eggs were removed and placed on chitin agar to isolate and identify associated fungi. Fungi encountered were mostly those previously known to be consistently associated with eggs of heteroderid nematodes. A fi