Management of Phytophthora capsici on bell pepper and Colletotrichum coccodes on tomato by using grafting and organic amendments

Trials were carried out in northern Italy in naturally and artificial infested soils in order to control emerging soil-borne pests on bell pepper and tomato by using grafting complemented with the use of organic soil amendments. A first set of trials was carried out under artificial inoculation of P. capsici in order to test the susceptibility of several rootstocks used for grafting pepper in Italy. In the second set of trials, carried out in field conditions, the efficacy of compost combined with susceptible pepper cultivars grafted onto resistant or partially resistant rootstocks to manage P. capsici was evaluated. The third set of trials was carried out to evaluate the efficacy of grafting, compost and biofumigation with Brassica carinata against Colletotrichum coccodes on tomato. Compost and biofumigation with Brassica pellets were also tested with and without grafting. Results showed that some of the commercially available rootstocks, 'Tecnico 1', 'Terrano', 'Robusto', 'Snooker' and 'Capsifort', were effective in controlling the incidence of Phytophthora blight. The use of compost reduced disease incidence in the trials carried out under natural infestation of the soil, while no significant effect was observed under artificial inoculation conditions. When pepper was grafted onto resistant rootstocks, the addition of compost showed little added value for disease control. When grafting and biofumigation were combined in a soil naturally infested with C. coccodes, biofumigation did not improve C. coccodes control in comparison to grafting alone. In a naturally infested soil, compost alone and combined with biofumigation improved disease control only on non-grafted 'Tomahawk' plants. Soil amendment with compost, in the case of the 'Arawak' and 'Tomahawk', resulted in a slightly improved disease control only on non-grafted plants.