Abstract

MARTINEZ, Benedicto et al. Antagonism of Trichoderma spp. isolates against Didymella bryoniae (Fuckel) Rehm. Rev. Protección Veg. [online]. 2013, vol.28, n.3, pp. 192-198. ISSN 1010-2752.

The aim of this work was to determine the action modes of Trichoderma spp. against Didymella bryoniae (Fuckel) Rehm. The competition by the substrate, antibiosis and mycoparasitism of Trichoderma asperellum Samuels (Ta), Trichoderma harzianum Rifai (Th) and Trichoderma sp. (T.) was assessed by the dual culture method. After 72 hours, all the isolates showed an inhibitory effect over the pathogen growth higher than 50%. The isolates Ta. 12, Ta. 79, Ta. 85 and T. 81 grew more than 75% of the plate area; thus, they were placed in the class 1 of Bell's scale. The growth rate of the two latter isolates increased from the 72 h, which could be related to attractive compounds emitted by the pathogen. Th A-34 and Ta. 85 presented the best indicators of parasitism with three types of hyphal interaction (coiling, vacuolization and penetration). The volatile metabolites produced by Th-34, Ta. 79 and Ta. 85 and those non-volatile emanating from Th A-34, Ta. 79 and T. 81 inhibited the pathogen growth from the 72h. According to the modes of action exhibited by the different isolates, Th A-34 and Ta. 85 were chosen as the best isolates for the control of D. bryoniae. They are emerging as potential candidates for biopesticide active ingredients, although their evaluation in the control of D. bryoniae under field conditions is required.

Keywords : Trichoderma asperellum; Trichoderma harzianum; action modes; gummy stem blight; cucurbits.

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