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On-line version ISSN 1678-4677
NECHET, Kátia de Lima and HALFELD-VIEIRA, Bernardo A.. Reaction of cowpea cultivars to web blight (Rhizoctonia solani) in Roraima, Brazil. Fitopatol. bras. [online]. 2007, vol.32, n.5, pp.424-428. ISSN 1678-4677. http://dx.doi.org/10.1590/S0100-41582007000500009.
Web blight caused by the fungus Thanatephorus cucumeris (Rhizoctonia solani) is one of most important diseases of cowpea (Vigna unguiculata) in the state of Roraima, Brazil. Web blight severity for ten cowpea cultivars was evaluated in Roraima in two consecutive years. The erect cowpea cultivars BRS-Mazagão, IT86D-719, Vita-7 (Epace-1), BR02-Bragança and Pitiúba, as well as the prostrate cultivars BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, were used. The experiment was conducted during 2005 and 2006 in a complete randomized block design with five treatments and four replications. The percentage of diseased foliage was evaluated once a week and the data were used to calculate the area under the disease progress curve. Disease severity was lower on prostrate cultivars indicating a relationship between plant architecture and web blight resistance. The prostrate cultivars, BRS-Amapá, BR03-Tracuateua, BR17-Gurguéia, BR14-Mulato and Canapuzinho, and erect cultivars, BRS-Mazagão, Pitiúba and BR03-Bragança, were more resistant to web blight and can be recommended for planting in areas where the disease is known to occur.
Keywords : Blackeye bean; Thanatephorus cucumeris; Vigna unguiculata.