Resumen
- The use of fungi as biological control agents against Phytophthora cactorum on apple rootstocks was evaluated. For this purpose, microorganisms were isolated from rhizosphere, roots, stems and soil from apple fields in Bocayá, Colombia that were affected and unaffected by the pathogen. From a total of 232 fungal isolates, 8 isolates belonging to the genus Beauveria, Clonostachys, Chaetomium and Trichoderma were selected for further testing as potential biological control agents. Two experiments were conducted under greenhouse conditions by using the apple rootstock MM106, whose shoots were inoculated with the pathogen and/or with the potential biological control agents. Significant disease control was achieved by using fungicide fosetyl-Al and seven biological treatments, when compared to the inoculated control. The most efficient treatments were Trichoderma sp. (Th 163) from soil, Clonostachys rosea (Cc 006) from rhizosphere, Clonostachys rosea (Cc 004) from stem, and the fungicide, with 77, 76, 74 and 70% protection, respectively.