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First Report of Phytophthora infestans A2 Mating Type in Ecuador

The tropical highlands of Ecuador are a genetic center for several Solanaceous species, including potato. In 1995 and 1996, severe late blight epidemics occurred in wild Solanum species, e.g., Solanum brevifolium, growing in the transitional area between the highlands and the coastal tropical lowlands near the city of Quito. Sixteen isolates of Phytophthora infestans were collected in 1995 and 36 isolates in 1996. Of these, three from 1995 and four from 1996 were A2 mating type. Extensive and systematic sampling of commercial potato and tomato in Ecuador have failed to reveal the presence of the A2 mating type (G. A. Forbes, X. M. Escobar, C. C. Ayala, J. Revelo, M. E. Ordoñez, B. A. Fry, K. Doucet, and W. E. Fry, Phytopathology, in press.). Apparently the A2 mating type reported for the first time in Ecuador is only associated with wild Solanaceous spp. Further research is required to determine the consequences of this event for management of late blight in both potato and tomato, two important field crops in the Andean highlands.