• Topics: Immokalee REC | Horticultural Sciences | Tomato | Tomato Varieties | Vavrina, Charles S | Southwest Florida

Growing Heirloom Tomato Varieties in Southwest Florida¹

Introduction

Heirloom tomatoes (Solanum lycopersicum L.) have seen a rebirth in popularity because of increasing demand for fresh, fully ripe, tasty tomatoes. Heirloom vegetables are nonhybrid varieties that have been preserved from generation to generation as seeds (Coolong 2009). Heirlooms are open pollinated, which means that the fruit is similar to the fruit of the previous generation (Flomo 2010). A tomato must meet three criteria to be considered an heirloom variety: The variety must be reproduced by seed, must have been cultivated for more than 50 years, and must have a history (Watson 1996). Many vegetables are available in heirloom varieties, and tomatoes are among the most important species (Figure 1). Heirloom tomatoes are known for their singular taste, shape, and color, which include purple, orange, and yellow, in addition to the common red tomatoes (Grassbaugh et al. 1999).

Figure 1. 

Common heirloom varieties growing in South Florida

Credit:

Monica Ozores-Hampton

[Click thumbnail to enlarge.]

Heirloom tomatoes are a trend food or part of a package sought by consumers who frequent farmers' markets, enjoy vegetable gardening, adhere to organic production, and explore specialty foods (Jordan 2007). However, since heirloom tomatoes are not the result of breeding programs, heirloom varieties are not generally disease resistant; therefore, heirlooms are more susceptible to pathogens and have lower heat tolerance than the F1 hybrid varieties (Flomo 2010). Heirloom tomatoes also have a shorter shelf life and are highly susceptible to bruising, which requires marketing within a few days after harvest (Coolong 2009). Given the impact of weather on tomato fruit production, heirloom tomato flavor and appearance are significantly impacted by high temperatures, and a variety of fruit defects can occur, such as blossom-end scar, catfacing, cracking, grey wall, and odd shapes that may make them unmarketable by commercial standards (Table 1). The target audience of this publication includes conventional and organic producers as well as home gardeners.

Grafting heirloom tomatoes

Grafting consists of splicing the shoot of one plant (called the scion) to the roots of another plant (called the rootstock) (Zhao and Simonne 2008) (Figure 2). The scion produces the desired heirloom fruit, and the rootstock is generally of a variety with some specific disease resistance (Rivard and Louws 2006). This technique can be used to manage soilborne diseases and increase fruit yield (Flomo 2010). The rootstock variety should be chosen by its genetic attributes, such as being resistant or tolerant to the target diseases (Table 3). Commercial seed companies provide both heirloom and suggested rootstock varieties (Table 2).

Grafting heirloom tomatoes can be an effective integrated pest management tool for growers who face heavy disease pressure from soilborne pathogens since many heirloom varieties are susceptible to soilborne diseases. Grafting has been used to manage Fusarium wilt (Fusarium oxysporum f.sp. lycopersici), Verticillium wilt (Verticillium dahliae), bacterial wilt (Pseudomonas solanacearum), Fusarium crown rot (Fusarium oxysporum f.sp. radicis-lycopersici), root-knot nematodes (Meloidogyne spp.), and tobacco mosaic virus (Zhao and Simonne 2008). A variety of methods can be used for grafting heirloom tomatoes, such as cleft grafting, tongue grafting, micrografting, and the most common commercial technique, tube grafting (Diánez et al. 2007; Ozores-Hampton, Zhao, and Ortez 2010; Rivard 2006).

According to Rivard (2006), there was no evidence of bacterial wilt when 'German Johnson' heirloom tomato was grafted to the resistant rootstocks 'CRA 66' and 'Hawaii 7996', as compared to 70%–75% disease incidence among nongrafted treatments. Also, a grafted 'German Johnson'/'Maxifort' union showed no Fusarium wilt, while nongrafted and self-grafted controls showed a 45%–50% disease incidence (Rivard 2006). Also, 'Maxifort' as a rootstock produced the greater yields with the highest fruit quality (Flomo 2010). For more information about how to grow vegetable transplants, see Vavrina (2011).

Figure 2. 

Grafting tomato plants by combining the shoot from a scion plant and the root from a rootstock plant using a grafting clip

Credit:

Monica Ozores-Hampton

[Click thumbnail to enlarge.]

Heirloom varieties

When choosing a suitable Florida tomato heirloom variety to grow, several factors need to be considered. First, identify the market or niche where the heirloom tomatoes are to be sold. Second, determine what flavors, shapes, and colors are preferred by consumers. Third, consider seed availability, pathogen pressure (except when using soilless media in the greenhouse or pathogen-resistant rootstocks), and the production system (conventional or organic).

During the spring seasons of 1997 and 1998, two open-field evaluations of 15 heirloom varieties were conducted at the University of Florida's Southwest Florida Research and Education Center (UF/SWFREC) in Immokalee (Table 4). Heirloom variety evaluation included fruit physical characteristics (average weight, size, number, and total yield/plant) (Table 5) and defect incidence (blossom-end rot, blossom-end scar, catfacing, concentric and radial cracking, grey wall, odd shape, and zipper scar) (Table 6). Additionally, the incidence of late blight (Phytophthora infestans) during the 1997 spring season prompted evaluation of varieties for susceptibility to the disease (Table 7).

Heirloom varieties 'Flamme', 'Mr. Stripey', and 'Pink Ping Pong' produced higher yields but of relatively small fruit compared to 'Clear Pink Early' and 'Garden Peach', which had medium yields of medium-sized fruit, while 'Arkansas Traveler', 'Eva Purple Ball', and 'Green Zebra' had lower yields of medium-large fruit. 'Arkansas Traveler', 'Clear Pink Early', 'Eva Purple Ball', 'Flamme', 'Green Peach', 'Green Zebra', 'Mr. Stripey', and 'Pink Ping Pong' produced fewer fruit defects compared to the other varieties. It should be noted that all heirloom varieties in the trials were considered poor candidates for the commercial Florida gassed-green tomato industry because they would not stand up to the harvesting, packing, and shipping protocols of the present-day culture.

Based on the above variety evaluation and an unpublished grower survey, open-field heirloom tomato varieties growing in Florida are summarized in Table 8. In areas affected by Fusarium wilt or Fusarium crown rot, grafted plants can be used to overcome these diseases.

Heirloom seeds

Heirloom tomato seeds can be obtained from commercial suppliers (Table 2) or can be collected and saved by the heirloom grower. When seeds are being saved for the next season, special care should be taken during the reproduction phases to maintain the purity of seeds to avoid unwanted crosses. The seeds should be harvested from the best plants to ensure that characteristics of the mother plant have been passed to the next generation. Additionally, be aware of suitable temperature and proper humidity (cool and dry) when drying and storing the seeds to preserve an acceptable germination rate (Coolong 2009).

References

Barten, J. H. M., and J. W. Scott. 1992. "Low temperatures induce rough blossom-end scarring of tomato fruit during early flower development." J. Amer. Hort. Sci. 117 (2): 298–303.

Bonina, J., and D. J. Cantliffe. 2009. Seed production and seed sources of organic vegetables. HS981. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs227.

Coolong, T. 2009. "Heirloom vegetables." Cooperative Extension Service, College of Agriculture, University of Kentucky. Accessed September 26, 2011. http://www.uky.edu/Ag/NewCrops/introsheets/heirloom.pdf.

Diánez, F., M. Díaz, M. Santos, V. Huitrón, M. Ricárdez, and F. Camacho. 2007. "The use of grafting in Spain." Paper presented at the Workshop on Non-Chemical Alternatives to Replace Methyl Bromide as a Soil Fumigant, Budapest, Hungary, June 26–28.

Flomo, S. T. 2010. "Investigation of yield and quality of grafted heirloom and hybrid tomatoes." Master's thesis, Western Kentucky University.

Grassbaugh, E., T. Harker, B. Bergefurd, and M. Bennett. 1999. "Specialty and heirloom tomato production and marketing." Ohio State University Extension. Accessed September 26, 2011. http://hostedweb.cfaes.ohio-state.edu/vegnet/reports/spectomw.htm.

Jordan, J. A. 2007. "The heirloom tomato as cultural object: Investigating taste and space." Sociologia Ruralis 47(1): 20–41.

Olson, S. M. 2009. Physiological, nutritional, and other disorders of tomato fruit. HS954. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs200.

Ozores-Hampton, M., G. McAvoy, S. Olson, K. Cushman, and N. Roe. 2011. Tomato varieties for Florida - Florida "red rounds," plum, cherries, and grapes. HS1189. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs1189.

Ozores-Hampton, M., X. Zhao, and M. Ortez. 2010. Introducción a la tecnología de injertos a la industria de tomate en la Florida: Beneficios potenciales y retos. HS1187. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs1187.

Rivard, C. L. 2006. "Grafting tomato to manage soilborne diseases and improve yield in organic production systems." Master's thesis, North Carolina State University.

Rivard, C. L., and F. J. Louws. 2006. "Grafting for disease resistance in heirloom tomatoes." Cooperative Extension Service, College of Agriculture and Life Sciences, North Carolina State University. Accessed September 26, 2011. http://www4.ncsu.edu/~clrivard/TubeGraftingTechnique.pdf.

Vavrina, C. S. 2011. An introduction to the production of containerized vegetable transplants. HS849. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/hs126.

Watson, B. 1996. Taylor's guide to heirloom vegetables. New York: Houghton Mifflin.

Zhao, X., and E. H. Simonne. 2008. "Introducing grafting technology to the Florida tomato industry: Potential benefits and challenges." Fla. Tomato Inst. Proc. PRO 524: 9–11.

Tables

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.

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