VIEW ARTICLE

Ecology and Epidemiology

Host Range and Host Colonization, Temperature Effects, and Dispersal of Fusarium oxysporum f. sp. citri. L. W. Timmer, Associate professor, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Center (IFAS, AREC), 700 Experiment Station Road, Lake Alfred 33850; Phytopathology 72:698-702. Accepted for publication 5 October 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-698.

Fusarium oxysporum f. sp. citri causes a serious wilt and dieback of Mexican lime (Citrus aurantifolia) in Florida greenhouses. Two commonly used rootstock species. Milam (C. jambhiri variant) and C. volkameriana, as well as C. amblycarpa were susceptible to the fungus, but other rootstock and scion species were resistant. All citrus species tested were invaded by F. oxysporum f. sp. citri, but the fungus was restricted to roots and stem bases in resistant species. Resistant rough lemon (C. jambhiri) and sweet orange (C. sinensis) showed symptoms when budded on susceptible Mexican lime rootstock. F, oxysporum f. sp, citri produced no symptoms on 39 species and cultivars of noncitrus plants, but invaded the stem bases of 15 species. Optimal temperature was 27–30 C for growth of the fungus in culture and 21–26 C for disease development. The means by which the fungus may be introduced into greenhouses remain unknown, but apparently it does not enter on seed or budwood. Within greenhouses the fungus was recovered on trap plates indicating possible dissemination by air.