Abstract

CEDENO, Luis et al. Identificación y virulencia de grupos de anastomosis de rhizoctonia solani kühn asociados con papa en mérida, venezuela . INCI [online]. 2001, vol.26, n.7, pp.296-300. ISSN 0378-1844.

In Venezuela potato (Solanum tuberosum) has economic relevance particularly in the Andean states (Mérida, Tachira and Trujillo), whose contribution to the national production is approximately 80%. In the last five years the Rhizoctonia disease, caused by Rhizoctonia solani, has become an important production limiting factor of potato production. The present study was carried out to determine the identity and virulence of R. solani anastomosis groups associated with potato in 12 localities of Mérida State and 1 locality in Trujillo State. One hundred and seventy six isolates whose hyphae and septa showed typical morphology of the fungi included in the Rhizoctonia Complex, were obtained from roots, stolons, petioles, and mainly from sclerotia on tubers. Of these isolates, 173 were multinucleate and 3 were binucleate. Multinucleate isolates were recognized as R. solani. One hundred sixty three R. solani strains were AG-3 and 10 belonged to AG-2-1. AG-3 and AG-2-1 isolates averaged 9.5 and 8.3 nuclei / vegetative cell, respectively. AG-3 strains were found in 12 out of 13 evaluated localities, and AG-2-1 strains in 3 localities. Only AG-2-1 strains were detected in one locality (El Valle). AG-3 and AG-2-1 strains were recovered from the same field in Bailadores and Mucuchies. As a group, AG-3 strains were more virulent than AG-2-1 strains. The wide dissemination and high virulence of AG-3 strains indicate that members of this group are the main cause of Rhizoctonia disease on the potato grown in Mérida and in Tuñame (Trujillo State).

Keywords : Papa ; Grupos de Anastomosis ; Rhizoctonia solani ; Solanum tuberosum ; Virulencia .