Project Highlights
FUNDED PROJECT RESULTS
Tomato Grafting Offers Promise in Disease Control
Grafting tomatoes on disease resistant rootstocks for
small-scale organic production
Investigator: Suzanne O'Connell, Horticultural Science Dept., North Carolina State University, Raleigh, North Carolina
Project location: Black River Organics, Ivanhoe, North Carolina
Summary
Organic tomato production is challenging in the Southeast due to high foliar and soilborne disease pressure. Grafting has been implemented successfully as a disease management tactic in commercial tomato production in various regions of the world including Asia, the Mediterranean and northern Africa. Herbaceous grafting is a site-specific management tool that can be tailored to the challenges of individual production systems using rootstock and scion selections.
Suzanne O'Connell/NCSU
Organic producer and project collaborator Stefan Hartmann of Black River Organics, with tomato seedlings headed for grafting in 2009.
The objectives of this study were to investigate the use of grafting to enhance organic field production of tomatoes at Black River Organic Farm in North Carolina. At this farm, high disease pressure from bacterial wilt (caused by Ralstonia solanacearum) has resulted in the grower abandoning open-field fresh-market tomato production.
Stefan Hartmann, owner and operator of Black River Organics, explains the relevance of this research to his situation. "The occurrence of tomato spotted wilt and the now regular problem of tomato bacterial wilt has jeopardized this very important part of our marketing strategy, reducing sales from tomatoes. Developing grafting procedures and cultivars has become a necessity for the continued survival of our farm, after exhausting all known organic remedies."
In Brief:
In this North Carolina-based study, investigators evaluated grafting as a means to manage intense tomato disease pressure. Trial results showed that grafting tomatoes onto disease-resistant rootstocks dramatically improved yields of marketable fruit, with top scion-rootstock pairings yielding 19.5 tons and net returns of $59,365 per acre.
Preliminary studies in 2007 indicated that ‘Celebrity’ scion grafted onto ‘RST-04-105-T’ (D. Palmer Seed Co., U.S.A) rootstock and ‘Dai Honmei’ (Asahi Seed Co., Japan) rootstock demonstrated complete and intermediate levels of resistance, respectively to bacterial wilt.
In 2008, the study was duplicated and expanded to include two additional rootstocks and to assist the grower with propagating grafted transplants on-farm.
We compared ‘Celebrity’ scion grafted onto four different rootstocks (‘RST-04-105-T,’ ‘Dai Honmei,’ ‘BWR,’ and ‘Sweet Olive’) compared to non-grafted and self-grafted (scion grafted back onto itself) controls. In 2008, soilborne disease pressure was very high as anticipated, but southern blight, caused by Sclerotium rolfsi, was the dominant disease rather than bacterial wilt. The rootstocks utilized in this study were selected for resistance to bacterial wilt but also demonstrated a range of resistance to southern blight.
‘Celebrity’- ‘RST-04-105-T’ grafts had the lowest incidence of southern blight, and and the greatest total fruit yields (19.5 T/A), followed by ‘Celebrity–BWR’ grafts (14.4 T/A), ‘Celebrity-Dai Honmei’ grafts (13.9 T/A), ‘Celebrity-Sweet Olive’ grafts (6.7 T/A), ‘Celebrity’ non-grafted (5.4 T/A), and ‘Celebrity’ self-grafted (4.6 T/A).
A cost and benefit analysis based on variable costs of grafted transplant production at the 1-acre scale, estimated $2,275 of additional transplant costs when grafted plants were utilized. The per acre net returns of the top yielding scion-rootstock combination, ‘Celebrity-RST-04-105-T,’ was $59,635.
The non-grafted ‘Celebrity’ crop generated $8,780 per acre.
Suzanne O'Connell/NCSU
Above, the treatment effects begin to separate in the research trial, with diseased plants showing in the foreground.
Because the grafted plants were able to maintain production under severe soilborne disease pressure, this cost-benefit analysis reflects the ability of disease resistant rootstock to reduce the risk of pathogen outbreaks and therefore add to on-farm economic stability.
Overall, the grower was very pleased with the results of this study and in 2009 continued to propagate and utilize grafted plants on-farm.
This final project report was submitted in August 2009.
Contact:
Suzanne O’Connell
Box 7609
Horticultural Science Dept.
North Carolina State University
Raleigh, NC 27695-7609
(919) 609-1498
suzanne.oconnell.gmail.com
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Collaborators:
Stefan Hartmann, Black River Organics, Ivanhoe, NC (certified organic since 1989)
Cary Rivard, Mary Peet and Frank Louws, Plant Pathology Dept., North Carolina State
University
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OFRF funding awarded:
Fall 2007: $11,174 (1 year)
Project period: 2008
Funding category: Research |
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