Abstract

MARTINEZ, B et al. SELECTION OF Trichoderma spp. ISOLATE CANDIDATES TO BIOFUNGICIDES FOR THE CONTROL OF Rhizoctonia sp. ON RICE. Rev. Protección Veg. [online]. 2008, vol.23, n.2, pp. 118-125. ISSN 2224-4697.

Sheath blight, caused by Rhizoctonia solani Kühn is considered the second important disease on rice in Cuba and the world. Trichoderma potentiality as antagonist of soil pathogen is recognized with positive results on R. solani. The present work had as objective to select the best Trichoderma isolates according to their in vitro antagonism and efficacy in the control of Rhizoctonia sp. in greenhouse and in the field. Antagonism was evaluated by the dual culture method, where the competition by the substrate, mycoparasitism and antibiosis were observed. The inhibition percentage of radial growth (IPRG) was calculated at 72 hours. The isolates with more than 60 PICR and at least two types of hyphal interaction were selected for being tested under greenhouse conditions, where the selection criterion was the technical efficacy (TE) under these conditions. Isolates with a TE higher than 80% were selected for field screening. The results showed that the 98,31% of the isolates had high antagonist capacity. They presented several hyphal interaction types such as lyses, vacuolization, coiling and penetration. Eleven Trichoderma isolates were selected in vitro. Of them, seven showed a TE higher than 80% in greenhouse. As promissories for the disease control in the field, isolates: 17, 75 and 78 with a TE higher than 90% were those highlighted under these conditions.

Keywords : Rhizoctonia sp.; Trichoderma; antagonism; hyphal interaction; antibiosis.

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