Abstract

FELIX-GASTELUM, Rubén et al. Identification and chemical control of the causal agents of leaf spot and powdery mildew of husk tomato (Physalis ixocarpa Brot.) in northern Sinaloa, Mexico. Rev. mex. fitopatol [online]. 2007, vol.25, n.1, pp.1-10. ISSN 2007-8080.

In recent growing seasons, leaf spot and powdery mildew have become economically important diseases in husk tomato in northern Sinaloa, Mexico. The objectives of this study were to: a) identify the causal agents of these two diseases, b) determine the sensitivity of the causal agents to three fungicides in vitro, and c) determine the biological efficacy of five fungicides to control these diseases under field conditions. The morphology of asexual structures of the fungus associated with leaf spot of husk tomato coincide with those reported for the genus Cercospora; which was pathogenic to husk tomato under artificial inoculation in the greenhouse. The morphometric characteristics of sexual structures and images of conidia under the scanning electron microscope indicated that the causal agent of powdery mildew of husk tomato was Podosphaera (Sphaerotheca) xanthii. In vitro, azoxystrobin, trifloxystrobin. and tcbuconazole inhibited 100% conidial germination of Cescospora at the rates at 0.02, 0.1. and 30.0 ppm. respectively. The same fungicides at the rates of 1.5, 0.1, and 5.0 ppm markedly inhibited mycclial growth. Three spray applications at weekly intervals of tebuconazole (Folicur® 0.6 L/ha), trifloxystrobin (Flint® 250 g/ha), chlorothalonil (Bravo® 720 2.5 L/ha) and benomyl + mancozcb (Benlate® + Mancozeb® 500 g/ha + 2.0 kg/ha) provided an excellent control of leaf spot and powdery mildew. The results of this study will allow growers to control both diseases efficiently in northern Sinaloa and in other husk tomato growing regions of Mexico.

Keywords : Fungal diseases; Podosphaera xanthii; Cercospora; fungicides; morphometric characteristics.

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