Disease Note.

Occurrence of a New Powdery Mildew Fungus (Erysiphe sp.) on Tomatoes in Hungary. L. Kiss, Plant Protection Institute of the Hungarian Academy of Sciences, P.O. Box 102, Budapest, H-1525 Hungary. Plant Dis. 80:224. Accepted for publication 6 December 1995. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/PD-80-0224E.

Powdery mildew on different cultivars of tomato (Lycopersicum esculentum Mill.) has been observed repeatedly since 1993, both in the field and in the greenhouse in Hungary. Mildew colonies of white color appeared on the upper and occasionally on the lower surfaces of the leaves. The small initial colonies enlarged quickly and merged to cover large leaf areas within 5 to 6 days. In the greenhouse, the infected leaves of cv. K262 withered within 7 to 9 days after the first symptoms appeared. Spread of infection was noticeable both in the field and in the greenhouse. The disease required chemical control in the greenhouse. Based on the characteristics of the anamorph, the pathogen was identified as an Erysiphe sp. Its ectophytic mycelium produced conidia in chains. Conidia contained no fibrosin bodies. Germ tubes with unlobed apexes arose from one end of conidia. Cleistothecia were not found, so a more exact identification of the species was not possible. Development of symptoms on tomato inoculated with the pathogen was similar to that of naturally infected plants. In contrast, inoculations did not result in any symptom on cucumber (Cucumis sativus L.) or tobacco (Nicotiana tabacum L.) plants. Infection of tomato crops with Erysiphe sp. was reported recently from Canada (I) and Greece (2). The disease has also been observed in other European countries (2). We report here for the first time its occurrence in Central Europe.