In vitro biological and chemical control of fungi associated with gummosis in citrus fruits in Yucatan, Mexico

Abstract

Background/Objective. In all citrus-producing regions in the world, gummosis is a disease that has caused losses in citrus production. This disease is caused by several pathogens. The objectives were to identify the fungi associated with gummosis in citrus orchards of Plan Chac, Sacalum, Yucatan; and to evaluate chemical and biological alternatives for the control of fungi associated with gummosis. Materials and Methods. From fragments of plant tissue and soil, the associated fungi were isolated. The isolates were identified morphologically in plant tissue as Lasiodiplodia pseudotheobromae and in soil as Fusarium solani and Pestalotia spp. The pathogenicity test determined that L. pseudotheobromae is an agent associated with this disease. The isolates were subjected to in vitro tests with chemical fungicides and antagonist agents. Results. Thiabendazole showed effectiveness for F. solani with an effective concentration to inhibit 50 % of the population (EC50) of 0.0612 mg L-1, with Pestalotia spp. inhibited growth at all concentrations evaluated and for L. pseudotheobromae, it showed an EC50 of 0.0049 mg L-1. In the case of Bacillus subtilis strain QST 713, the growth of F. solani (EC50 0.0496 mg L-1), Pestalotia spp. (EC50 0.0487 mg L-1) and L. pseudotheobromae (EC50 0.0528 mg L-1) decreased. On the other hand, Trichoderma harzianum showed a greater inhibition against F. solani, Pestalotia spp. and L. pseudotheobromae of 61.08, 62.93 and 35.64 %, respectively. Conclusion. In the management of gummosis in citrus fruits, the use of biological agents such as Trichoderma and B. subtilis can be efficiently included, offering alternatives with less impact on the environment.