In vitro evaluation of antagonists against soursop fruit pathogens (Annona muricata L.) in Nayarit, Mexico

Abstract In Nayarit, Mexico, soursop production is affected by the pathogens of Pestalotiopsis sp. and Colletotrichum gloeosporioides that cause dry rot and Lasiodiplodia pseudotheobromae soft rot. In the present study, the in vitro antagonism of three species of Streptomyces, three of Trichoderma and three of Bacillus were evaluated. The Trichoderma strains showed different inhibition in the pathogens evaluated, Trichoderma longibrachiatum showed the highest PIRG in vitro, which was 60.45, 59.33 and 57.9 when confronted against C. gloeosporioides, Pestalotiopsis sp., and L. pseudotheobromae, respectively. The bacteria showed lower PIRG than the fungi. B. methylotrophicus exhibited the highest capacity of inhibition of the experiment with 58.22 % of PIRG against Pestalotiopsis sp. The Streptomyces strains were the most effective and could be studied in future researches on the biological control of fruit pathogens, since they exerted 100 % inhibition except S. viridochromogenes that presented a percentage of inhibition of radial growth (PIRG) of 88.3 % against Lasiodiplodia pseudotheobromae.