Control of Colletotrichum coccodes on Tomato by Grafting and Soil Amendments

Eight trials were carried out in 2011 and 2012 in N orthern I taly to evaluate the efficacy of grafting, compost and biofumigation with B rassica carinata against C olletotrichum coccodes on tomato. Four trials were carried out in commercial farms, and four trials were carried out in plastic tunnels at an experimental centre. The rootstocks ‘ A rmstrong’, ‘ A rnold’, ‘ B eaufort’, ‘ B ig P ower’, ‘ B rigeor’, ‘ E mperador’, ‘ K ing K ong’, ‘ S pirit’ and ‘ S uperpro V295’ were tested. Host plants included several tomato F1 hybrids: ‘ A mantino’, ‘ A rawak’, ‘ CLX 37438’, ‘ C auralina’, ‘ CU 8301’, ‘ CU 8506’, ‘ DRK 7021’, ‘E 34431’, ‘E 50070’, ‘ EXP ’, ‘ G otico’, ‘ I ngrid’, ‘ ISI 61401’, ‘ ISI 61402’, ‘ P rofitto’, ‘ P unente’, ‘ R ugantino’ and ‘ T omahawk’. Tomato roots from the control plots were 34 to 87% diseased in both naturally and artificially infested soil. Among the nineteen commercial tomato hybrids tested, in the presence of a very high disease pressure in a naturally infested soil, ‘ R ugantino’ was the least affected by C. coccodes, showing 32% infected roots. ‘Tomahawk’ grafted onto ‘ A rnold’, ‘ A rmstrong’ and ‘ S uperpro V295’ was significantly less affected by C. coccodes , while ‘ A rawak’ grafted onto ‘ A rmstrong’, ‘ A rnold’, ‘ E mperador’ and ‘ B eaufort’ provided very good control of root rot in the different trials. Compost addition and biofumigation with B rassica pellets were also tested with and without grafting. Soil amendment with compost, in the case of the ‘ A rawak’ and ‘ T omahawk’, resulted in a slightly improved disease control only on non‐grafted plants. When grafting and biofumigation were combined in a soil naturally infested with C. coccodes and M eloidogyne arenaria , biofumigation did not improve C. coccodes control in comparison with grafting alone. In a naturally infested soil, compost alone and combined with biofumigation improved disease control only on non‐grafted ‘ T omahawk’ plants. In general, grafting by itself provided very good results in terms of disease control, which were not significantly improved by combination with compost and/or biofumigation.