Grafting Using Rootstocks with Resistance to Ralstonia solanacearum Against Meloidogyne incognita in Tomato Production

Root-knot nematodes (RKNs; Meloidogyne spp.) and Ralstonia solanacearum, the causal agent of bacterial wilt, are major soilborne pathogens in U.S. tomato production. Methyl bromide has been used for decades to effectively manage RKN but its phase-out and the high cost of other effective fumigants such as 1,3-dichloropropene has resulted in a need to develop sustainable alternatives. Many of the commercially popular varieties used by the tomato industry do not have resistance to RKNs and R. solanacearum. Recent studies worldwide have shown the potential for grafting using resistant rootstocks as a sustainable and ecofriendly practice for R. solanacearum management. However, the effectiveness of R. solanacearum-resistant rootstocks on RKN management is not known. In this study, three commercially available R. solanacearum-resistant tomato rootstocks ('RST-04-106-T', 'BHN 998', and 'BHN 1054') were evaluated for resistance to Meloidogyne incognita in field tomato production in four field trials conducted for two consecutive years in two geographical locations: Florida and Virginia. Grafting rootstocks onto 'BHN 602' a tomato scion susceptible to bacterial wilt and RKNs, significantly reduced root galling caused by RKNs in all four field trials and increased yield in two of the trials compared with the nongrafted treatment. This study demonstrates the potential of grafting for managing multiple soilborne pathogens using the same rootstocks.