A Leaf Blight ofEucalyptusSeedlings in South African Nurseries Caused byHainesia lythri

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Abstract
Heavy losses occurred in frost-tolerant gum nurseries in the eastern Transvaal in spring 1982, 1983 and 1984. Affected seedlings showed severe leaf spotting, stunting, multiple stems and death. Isolations from symptomatic tissues consistently yielded Hainesia lythri, which was pathogenic on inoculated seedlings. Host range studies showed the following Eucalyptus species to be susceptible; E. fastigata, E. fraxinoides, E. nitens, E. cloeziana, E. camaldulensis, E. diversicolor, E. macarthurii, E. maculata, E. melliodora, E. microcorys, E. orcades, E. smithii and E. tereticornis. E. grandis and E. deanei were resistant. Infection occurred only when leaves were wounded and free moisture was present. In the nurseries studied, leaves were wounded by application of granular fertilisers and overhead mist irrigation systems provided free water for infection.