Selection of cacao trees resistant to Ceratocystis wilt by inoculation in leaf discs and field

Ceratocystis wilt, currently one of the main diseases of cacao tree, is difficult to control, and the priorities are to find sources of resistance and to develop quick methodologies for evaluation. A quick methodology has been developed, the leaf disc (LD) method. In the present study, the resistance to C. cacaofunesta of 39 clones of cacao ( Theobroma cacao L.), under field conditions and through the LD method has been evaluated. Woody branches and leaf discs (1.5 cm diameter) were inoculated with 30 μL and 20 μL, respectively, of the suspension with 3 × 10 4 CFU/mL of Ceratocystis cacaofunesta . Sixty days after inoculation in the field, inoculated and control branches were collected to evaluate the length, width, and area of the lesions. In leaf discs, the number of perithecia formed was counted after four days. Twenty-six new sources of resistance to C. cacaofunesta were selected through both inoculation methods. The LD method can be applied to a higher number of genotypes (increasing selection intensity) and much earlier than the field method.