Fitopatologia Brasileira (2006) 31, p. 320 (Halfeld-Vieira et al.)

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Bernardo A. Halfeld-Vieira, Kátia L. Nechet and Rosianne N.T. Barbosa (2006)
Pseudocercospora fuligena causing leaf mold of tomato in Roraima, Brazil
Fitopatologia Brasileira 31 (3), 320-320
Abstract: Cercospora leaf mold on tomato is an uncommon disease in Brazil. In September 2005, in Roraima, Brazil, tomato (Lycopersicon esculentum L.) plants cv. Santa Clara growing in protected cultivation conditions presented a severe foliar blight. Symptoms initially appeared as foliar spots, yellow on the adaxial leaflets surface, corresponding to a dark gray fuliginous growth on the abaxial surface, evolving to irregular necrotic spots. As the disease developed, leaf spots coalesced. Characteristics of the associated fungi were fascicles amphigenous, predominantly hypophyllous, effuse, stromata absent or substomatal. Conidiophores pale olivaceous to olivaceous brown, 9-16 per fascicle, 20-39 x 3.5-5.0 µm, 1-2 septate, conidiogenous loci inconspicuous. Conidia obclavate to cylindric-obclavate, rounded to obtuse at the apex, olivaceous to subhyaline, obconic to rounded at the base, 29-110 x 2.5-5.0 µm and 3-10 septate, hila unthickened, not darkened. To perform the Koch's postulates the fungi was isolated in Potato Dextrose Agar and cultivated in Potato Dextrose broth at 28 ºC in rotary shaker. After 20 days, the culture was centrifuged, dispensing the culture media. Mycelium was resuspended in sterilized tap water and triturated. Thirty-days old plants of tomato hybrid Débora Plus were sprayed with the mycelium suspension (1.6 x 105 mycelium fragments per mL), kept in humid chamber for 24 h and then transferred to greenhouse conditions. As control, plants were sprayed with tap water. For each treatment, 20 plants were utilized. After nine days, first symptoms were observed only in plants sprayed with the mycelium suspension, evolving to an intense foliar blight. The pathogen was successfully re-isolated. These features permit the identification of Pseudocercospora fuligena (Roldan) Deighton (basionym Cercospora fuligena) as causal agent of cercospora leaf mold on tomato. This is the first report of P. fuligena on tomato in Roraima state, Brazil. The symptoms of the disease are easily confused with Cladosporium leaf mold.
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Database assignments for author(s): Bernardo de Almeida Halfeld-Vieira

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Pseudocercospora fuligena Tomato (Solanum lycopersicum) Brazil (NW)