Invasion of white clover roots by fungi and other soil micro-organisms IV. Survey of root-invading fungi and nematodes in some New Zealand pastures

摘要

Abstract Microbial invasion of white clover roots in turf samples from grazed pasture at 48 sites in New Zealand was investigated, using microscopy and plate culture isolation techniques to identify fungi and nematodes. Clover cyst nematode (Heterodera trifolii Goffart), root knot nematode (Meloidogyne spp.), and root lesion nematode (Pratylenchus spp.) were detected by microscopy in samples from 75%, 58%, and 48% of sites respectively. Mycorrhizal infections (from 88% of sites), thalli of Polymyxa graminis Ledingham (29%), and oospores of oomycete fungi (19%) were also detected in roots examined by microscopy. Fungi frequently isolated from segments of surface-sterilised roots, and predominant amongst isolates at one or more sites were: Bimuria novae-zelandiae D. Hawksw., Chea & Sheridan, Codinaea fertilis Hughes & Kendrick, Fusarium oxysporum Schlecht., Phoma chrysanthemicola Hollós, species of Chrysosporium, Cylindrocarpon, and Colletotrichum, and fungi with sterile dark or sterile white mycelium. Thes...