Understanding Tomato Varieties

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Tomatoes are easily the most popular crop grown in home vegetable gardens (though the part we eat is most assuredly a fruit!). Originating in Mesoamerica, tomatoes were introduced to Europe in the 16th century and have since become integral in Mediterranean cuisine.

Tomato cultivars are diverse, with different combinations of fruit size, growth habit, and disease resistance. Cherry tomatoes are the easiest to grow and tend to have the fewest disease problems. They’re great for snacking and for salads. Roma or plum tomatoes have thicker rinds and fewer seeds and are excellent for processing. The larger, rounded beefsteak types are what most gardeners crave, but can be the trickiest to grow.

Determinate tomato varieties produce flowers (and therefore fruit) on the terminal ends of stems, which keeps the plant relatively compact, and produce one, simultaneously maturing crop. These features make determinate varieties well suited for growing in containers and for producing a lot of fruit for canning or processing. Indeterminate varieties produce flowers on lateral stems, so plants keep growing and continuously produce fruit throughout the season. Indeterminate varieties require caging or staking for support. Semi-determinate varieties stay relatively compact, but produce fruit continuously.

Heirloom tomatoes are varieties that have been preserved for several generations and selected for particular taste, texture, and color qualities. Heirloom varieties are open pollinated and breed true: seeds saved produce fruit with the same characteristics as their parent plants. Heirloom varieties that perform well in our area include ‘Cherokee Purple,’ ‘German Johnson,’ ‘Homestead,’ and ‘Marglobe.’ While heirloom varieties are well regarded for their flavor qualities, they are susceptible to wilt diseases, which are fungal or bacterial infections of the plant vascular systems. Vascular wilts are incurable and fatal to tomato plants.

Fortunately, clever plant breeders from seed companies and university breeding programs developed many ‘hybrid’ varieties resistant to several types of diseases. Ever wonder what those series of capital letters are on seed packets and transplants? They denote which diseases that cultivar is resistant to. For example, a “Big Beef’ hybrid might have the letters “VFFNTASt” on the seed packet, which means the cultivar is resistant to Verticillium wilt (‘V’), two strains of Fusarium wilt (‘FF’), nematodes (parasitic roundworms, ‘N’), tobacco mosaic virus (‘T’),  Alternaria (a type of leaf disease, ‘A’), and Stemphylium (grey leaf spot, ‘St’). If you have had problems with tomato diseases in the past, I strongly recommend using disease resistant hybrid seeds. No hybrid seed cultivar is resistant to all diseases, however. Hybrid seeds also do not ‘breed true’, so the seeds from the fruit you grow will produce offspring different than their parents. Nonetheless, many modern hybrid varieties have excellent flavor qualities. Some of the best varieties for our part of North Carolina include: ‘Better Boy,’ ‘Celebrity,’ ‘Early Girl,’ and ‘Big Beef’. For cherry tomatoes, look for   ‘Juliet’, ‘Sweet 100,’ and ‘Sweet Million.’

Matt Jones is Horticulture Agent for North Carolina Cooperative Extension in Chatham County.