Grafting Tomatoes to Manage Disease & Increase Fruit Yield

1. Grafting Tomatoes to Manage Disease & Increase Fruit Yield Cary L. Rivard, Ph.D. January 15, 2011 Future Harvest Conference www4.ncsu.edu/~clrivard

2. NC STATE UNIVERSITY Top Row: Frank Louws, Chris Harlow, Cary Rivard, Steve Moore Bottom Row: Mary Peet, Suzanne O’Connell, Josh Moore

3. Tomato Grafting • First reports of vegetable grafting occurred in Asia in the 1920’s. • Fusarium wilt of melon • Popularized in Japan and Korea • Tunnel and Greenhouse production Scion Rootstock

4. Vegetable Grafting Worldwide 81% of Korean and 54% of Japanese vegetable production uses grafted plants (Lee, 2003) Photos courtesy of M. Peet (NCSU)

5. Benefits of Grafting • Root function • Disease resistance against soilborne pathogens • Water and nutrient uptake • Nutrient assimilation and transport • Interface with soil ecosystem

6. Major soilborne diseases in NC. • Verticillium Wilt • Fusarium Wilt • Root-knot Nematodes • Southern Blight • Bacterial Wilt = 2008 = 2009 = On-farm trials = NCDA Research Stations = 2005 = 2006 = 2007

7. Disease Management R=Resistant , HR=Highly Resistant, MR=Moderately Resistant, S=Susceptible * = De ‘Ruiter Seed Co. ** = Sakata Seed Co. *** = Asahi Seed Co. **** = D Palmer Seed Co. ***** =Rijk Zwaan ****** = Bruinsma Seed Co.

8. Disease Management R=Resistant , HR=Highly Resistant, MR=Moderately Resistant, S=Susceptible * = De ‘Ruiter Seed Co. ** = Sakata Seed Co. *** = Asahi Seed Co. **** = D Palmer Seed Co. ***** =Rijk Zwaan ****** = Bruinsma Seed Co.

9. Disease Management • Ralstonia solanacearum • Soil inhabitant • Wide host range • Easily dispersed in water and soil • Bacterial Wilt • Disease complex • No host resistance in commercial cultivars • Resistance is strain-specific and may not be durable over geographic locations.

10. Disease Management • Sclerotium rolfsii • Wide host range • Very common in soils with high OM • Uses oxalic acid to destroy host tissue • Southern Blight • Permanent wilt • Hot weather No known resistance in commercial cultivars Sclerotia form on tomato stem

11. Cedar Meadow Farm Steve Groff Cedar Meadow Farm – Lancaster County, PA

12. Verticillium Wilt • Verticillium dahliae • Loss of vigor • Wilting and leaf necrosis • Favored by cool wet weather • Race 2 prevalent in WNC (Bender &Shoemaker, 1984) • Reliance on fumigation

13. Cedar Meadow Farm Research Objectives • Can vigorous rootstock be used to manage verticillium wilt? • How does grafting fit in with fumigation? • Additive or alternative • Can we reduce economic constraints through cultural methods? • Plant spacing (2008) • Transplant costs (2009) Kaitlin Dye (Summer 2008) Photo Courtesy: Steve Groff

14. Cedar Meadow Farm C C B A Lancaster County - 2009 80 70 60 50 Marketable fruit yield (tons/acre) 40 30 20 10 0 Non-Fumigated Fumigated Non-Fumigated Fumigated Non-grafted Maxifort LSD P = 0.05

15. Cedar Meadow Farm C C BC B B A LSD based on P=0.05

16. Economics * Values = Gross revenue – harvest costs – transplant costs Selling price = $0.66 per lbs

17. Benefits of Grafting • Root function • Disease resistance against soilborne pathogens • Water and nutrient uptake • Nutrient assimilation and transport • Interface with soil ecosystem

18. 2006 SR-SARE R&E Grant Compare production dynamics of tunnel vs field production. Environment Disease Productivity Economics Optimize cultural practices for high tunnels. Nutrient / Fertility Planting Date Investigate the role of grafting for open-field and tunnel production. Beaufort Maxifort Nutrient uptake efficiency CEFS Research ‘Cherokee Purple’

20. Cultural Management • European string trellis in tunnels • Stake-and-weave in field • 4.5 ft row spacing Stake-and-weave in field Twin leader in tunnel

21. Grafting Effects - Nutrients

22. Grafting Effects - 2007 BEAUFORT MAXIFORT 42 % 53 % The main effect of grafting was significant in both years, across systems, and with both data sets (100 DAP vs “systems”). System*grafting = NS

23. Grafting Effects - 2008 BEAUFORT MAXIFORT 37 % 35 % The main effect of grafting was significant in both years, across systems, and with both data sets (100 DAP vs “systems”). System*grafting = NS

24. Conclusions • Grafting provides a site-specific management tool for soilborne disease. • Disease diagnosis and rootstock selection are critical. • Use of rootstocks may increase yield through added vigor and nutrient uptake. • Cultural management may reduce economic constraints. • Planting density • Pruning/training • Fertility

25. Grafting at NC State Suzanne O’Connell (NCSU)

26. Tube Grafting

27. Disclaimer • No Recipe for Success • Principles • Production • Uniformity • Water Stress • Sanitation • Re-acclimation

28. Propagation Costs • Proportion of added costs • e.g. seed costs (%) = (SEEDgraft - SEEDnon) / (TOTALgraft - TOTALnon) $0.46 / plant $0.74 / plant = Added cost (Rivard et al., 2010)

29. Tube Grafting • The advent of “tube-grafting” or “Japanese top-grafting” has become the most popular for tomato. • Seedlings are grafted at 2-4 leaf stage. • High Throughput • A person can make ~ 1000 grafts/day • Grafting robots can make 700 grafts/hr.

30. Timeline

31. Seeding / Transplant Production • Uniformity is key • Germination period • Substrate • Transplanting / Sowing • Rootstock and scion • Numbers • Plastic trays • Healing Chamber

32. Tube Grafting Technique • Size: • 2-4 leaves • 1.5-2.0 mm stem diameter • Sorting • Temperature can be manipulated to compensate for size differences. • Timing is critical.

33. Tube Grafting Technique • Preparing for surgery… • Make sure plants are not water or nutrient stressed. • Have a clean working area. • Disinfect hands, tools, and grafting clips. • Carry out grafting indoors • Be in close proximity to healing chamber.

34. Tube Grafting Technique • Angle of cut • Clip attachment • Scion insertion • Provide good contact between the rootstock and the scion.

35. Life in the Chamber • During the healing process, the plant has to form callus tissue and reconnect vascular bundles within the stem.

36. Life in the Chamber • By altering the plant’s physical environment, we can offset the functional effects that this trauma has incurred, and give the plant time to heal itself…

37. Life in the Chamber • Objectives of the healing chamber • Reducing water stress by slowing the transpirational stream. • Humidity • Light • Temperature • Keep temperature fairly constant and between 75 and 80 degrees F.

38. Life in the Chamber • Regulate humidity • Cool-water vaporizers • Hermedifiers • Passive humidifiers • No warm-water vaporizers • No misters PLEASE • Overhead watering Small cool-mist vaporizer (~$40). Note: 1.5” PVC connectors to direct water vapor

39. Regulate light & humidity in the chamber

41. Healing Chamber

46. Life in the Greenhouse • 7-10 days in the Greenhouse • Hardening off • Overhead Watering • The Clip • Transportation

47. Life on the Farm Planting Depth Suckering

48. Early Tomato Production

49. Life on the Farm MAXIFORT NON-GRAFTED

50. Life on the Farm Twin leader for stake-and-weave Twin leader for European string trellis