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

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 trifoliiGoffart), root knot nematode (Meloidogynespp.), and root lesion nematode (Pratylenchusspp.) were detected by microscopy in samples from 75, 58, and 48 of sites respectively. Mycorrhizal infections (from 88 of sites), thalli ofPolymyxa graminisLedingham (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-zelandiaeD. Hawksw., Chea amp; Sheridan,Codinaea fertilisHughes amp; Kendrick,Fusarium oxysporumSchlecht.,Phoma chrysanthemicola Holl#xF3;s, species ofChrysosporium, Cylindrocarpon, andColletotrichum, and fungi with sterile dark or sterile white mycelium. These fungi accounted for 73 of all isolates.Fusarium culmorum(W. G. Smith) Sacc.,F. avenaceum(Corda ex Fr.) Sacc.,Ceratobasidium cornigerum(Bourd.) Rogers, species ofAcremonium, Gliocladium, Phomopsis, Phoma, Penicillium, Trichoderma, andPericonia, and some unidentified oomycetes and basidiomycetes accounted for 22 of fungal isolates, but none was predominant at any site.