Resumo

DIAZ FRANCO, Arturo; MENDEZ RODRIGUEZ, Asunción  e  GARZA CEDILLO, Rubén. Buffelgrass leaf blight: its precence in Tamaulipas, Mexico. Agric. Téc. Méx [online]. 2007, vol.33, n.3, pp.285-295. ISSN 0568-2517.

In the semiarid region of northern Tamaulipas, Mexico, buffelgrass (Cenchrus ciliaris L.) var, Comun predominate in 260 000 ha and there are 360 000 additional suitable to be sown with this grass. The objective of this study was to determinate the distribution, severity and production loss caused by the leaf blight (Piricularia grisea) on buffelgrass. Samples were taken from northern Tamaulipas range lands at 15 sites on 2002 and 12 sites on 2003. The incidence and severity of leaf blight was registered for every site with three replications from 8/13 to 8/18 for both years. Yield loss was determinate at spring-summer season 2004 and fall-winter 2005 by means of comparison between fungicide protected and unprotected plants. The reaction of buffelgrass to foliar blight was determinated on 16 introduced cultivars. Leaf blight presence was detected at all sites with an average severity of 5.3 in a scale from 0 to 9 .The highest attack severity was observed on plants stressed by drought or adverse edafic conditions; while the lower severity was observed on sites where favorable conditions occurred or when the grass was at the preflowering stage. At the spring-summer 2004 season losses were 11% in chlorophyll content, 20-26% in biomass and 13% in protein content; on the contrary, no significant reduction of these parameters was observed at the fall-winter season 2005. The 16 introduced cultivars showed resistance to Pyricularia gricea. Results demonstrated that buffelgrass leaf blight is an epidemic disease in the Comun var., in Tamaulipas, with high prevalence at the spring-summer season and there is resistance to the disease in introduced cultivars.

Palavras-chave : Cenchrus ciliaris L.; Pyricularia grisea; distribution; severity; losses production; resistance cultivars.