Grafting for soilborne disease management in Australian vegetable production systems—a review

Grafting a susceptible seedling onto a resistant or tolerant rootstock provides resistance or tolerance to a commercial variety without the need for time consuming and costly breeding programs. Until recently grafting for soilborne pathogen (SBP) management for in-field Australian vegetable production has been evaluated for a small number of crops without consideration for wider use. Here we review the literature to ascertain the utility of grafting for SBP management for multiple-harvest high-value Australian vegetable crops. We matched Australian vegetable disease reports against reports for management of the causal SBPs by grafting and found in other countries that 12 crop-pathogens can be managed by grafting specifically for six Australian vegetable crops (capsicum, cucumber, eggplant, melon, tomato, and watermelon). We identify technical hurdles that need to be addressed for the effective adoption of grafting systems from other countries for SBP management in Australia, including the compatibility of resistant stocks to Australian vegetable cultivars and determining the effects of grafting on non-target pathogens. There are also technical issues in terms of the capability of the method under Australian conditions, including the lower resistance of some rootstocks during high soil temperatures, the management of disease complexes, and preventing the selection of virulent populations of target pathogens. We suggest that the development of soil inoculum quantification and disease risk assessments for pre-transplant site assessments would be an important aid for determining when grafted seedlings are required and for evaluating efficacy in relation to inoculum pressure.