Grafting heirloom tomatoes for organic high tunnel production to improve season extension, disease control, and fruit yield: A partnership with local growers for technology transfer

Grafting heirloom tomatoes for organic high tunnel production to improve season extension, disease control, and fruit yield: A partnership with local growers for technology transfer

Summary

A grafted tomato experiment was established in the organically managed high tunnel at the Frog Song Organics farm, Hawthorne, FL. This on-farm trial was designed to help the grower overcome the soil-borne disease problem in his high tunnel tomato system under organic production. As suggested by the growers, four indeterminate tomato cultivars varying in fruit size and color were selected, including ‘Sun Gold’, ‘Green Zebra’, ‘Supersweet 100’, and ‘Black Cherry’. They were grafted onto two commercial tomato rootstocks ‘Multifort’ and ‘Estamino’, respectively. The eight grafting combinations will be compared with the four non-grafted tomato scion cultivars in this study.   

Objectives/Performance Targets

Objective 1. Determine the effectiveness of grafting with resistant rootstocks for controlling soil-borne diseases in specialty tomatoes grown in organically managed high tunnel.

Objective 2. Assess fruit yield and quality as affected by grafting with vigorous disease-resistant rootstocks. 

Objective 3. Analyze the costs and returns of high tunnel production of grafted tomatoes to determine its economic feasibility in a commercial operation setting.

Accomplishments/Milestones

We collaborated with the Frog Song Organics farm (Hawthorne, FL) in this on-farm research project to conduct a site-specific evaluation of grafting as an economically feasible tool for soil-borne disease management in organic tomato production in the high tunnel system. Based on the growers’ interest and recommendation as well as the growing season, we decided to focus on specialty tomatoes rather than heirloom tomatoes in this study. Four indeterminate tomato cultivars were selected for this grafted tomato study in the organically managed high tunnel. These specialty tomato cultivars differ in fruit size and color, including: ‘Sun Gold’ (bright tangerine-orange cherry tomato), ‘Supersweet 100’ (red cherry tomato), ‘Black Cherry’ (cherry tomato fruit almost black in color), and ‘Green Zebra’ (3-4 oz. green fruit with yellow blush and darker green stripes). Two commercially available rootstocks ‘Multifort’ and ‘Estamino’ were used to graft the four tomato scion cultivars, respectively. ‘Multifort’ is a robust interspecific tomato hybrid rootstock with great vigor which has resistances to Fusarium wilt, Fusarium crown and root rot, Verticillium wilt, root-knot nematodes, and corky root. ‘Estamino’ is a vigorous tomato rootstock with resistances to Fusarium wilt, Verticillium wilt, root-knot nematodes, and Fusarium crown and root rot, which is also claimed to produce a more balanced grafted plant favoring fruit production. Tomato scion and rootstock seeds were planted in October 2014 and the plants were transplanted in late December 2014. The eight scion-rootstock combinations and the four non-grafted tomato scion cultivar controls were arranged in a randomized complete block design with 3 replications and 5 plants in each plot. During the production season we will monitor the incidence of Fusarium wilt and other soil-borne diseases. Fruit weight and number (with marketable and cull fruit separated) will be measured at each harvest, and tomatoes will be sampled during the peak harvest for fruit quality assessment. Economic analysis will also be conducted to compare the profitability of using non-grafted vs. grafted plants in the organic high tunnel system.

Impacts and Contributions/Outcomes

Development of this project is largely driven by growers’ interest and their active participation in improving long-term sustainability of vegetable production. The growers identified the Fusarium wilt problem in high tunnel production of organic tomatoes from their experience with yield loss in the previous season at Frog Song Organics. Grafting was introduced to them while they were searching for new management tools to improve their current production system. The lack of disease resistance in many of the heirloom and specialty tomato cultivars is a constant challenge for growers. By involving farmers in designing this project, our research findings will provide up-to-date information on using grafting with appropriate rootstocks to manage devastating pest problems in organic specialty tomato production under high tunnel. Results from this study will also be useful to other growers who are seeking non-chemical IPM tools for their production systems. Moreover, this on-farm project responds in a timely manner to the critical research needs for developing sustainable high tunnel cropping systems in the South to address production challenges associated with pest problems and environmental stresses. 

Collaborators: