Abstract

SANABRIA VELAZQUEZ, Andrés Dejesús. Evaluation of Paraguayan native strains of Trichoderma spp. for the control of Colletotrichum spp. causal agent of strawberry anthracnose. Investig. Agrar. [online]. 2020, vol.22, n.1, pp.53-62. ISSN 2305-0683.  https://doi.org/10.18004/investig.agrar.2020.junio.53-62.

One of the most studied and effective biological control agents in several phytopatosystems is the fungus Trichoderma spp.. However, in Paraguay there are no commercial products based on native isolates. The objective of this work was to select Trichoderma isolates native to Paraguay as biocontrol agents of Colletotrichum spp. causal agent of the anthracnose in strawberries. It was measured the average speed of growth, degree of mycelial overlap and capacity of inhibition of growth in vitro of the plant pathogen Colletotrichum spp. using the dual culture technique. Significant differences were observed between isolates of Trichoderma spp. for the inhibition of growth of Colletotrichum spp. with values ​​of 50.00 to 74.44%, being the native isolate TFC14-06 the one that exerted the greatest inhibition. To evaluate the effect on strawberry production, weekly applications of spore suspension mix of Trichoderma spp. TKC14-03, TFC14-06 and TFLE-08 were carried out in the experimental plots of strawberry cv. Dover in the CIHB/IPTA. During field evaluations under conditions of natural infection, no significant differences were observed between control treatments and treated with Trichoderma spore suspension. In conclusion, the native isolates TFC14-04, TFC14-05, and TFC14-06 have antagonistic potential against Colletotrichum spp. based on their ability to inhibit pathogen growth in vitro. However, the effect of the application of the spore suspension of Trichoderma isolates on strawberry production under conditions of natural infection was not observed. Therefore, future screening experiments of native Trichoderma isolates should evaluate their effect under controlled environmental conditions that ensure high disease pressure.

Keywords : Biological control; Fragaria × ananassa Duchesne; fungi; IPM.

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