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HORT410 - Vegetable Crops

Tomatoes - Notes

Tomato Flower Cluster, David Rhodes

  • Common name: Tomato.
  • Latin name: Lycopersicon esculentum Mill.
  • Family: Solanaceae or nightshade family [Solanaceae Images].
  • Closely related species grown as vegetables: potato, eggplant, and pepper.
  • Diploid (2n = 24).
  • Dicotyledon.
  • Perennial, grown as an annual in temperate climates.
  • Warm-season, frost-sensitive.
  • Origin: Central America.
  • Spanish explorers introduced tomato into Europe and North America.
  • The tomato became popular in the U.S. only in the 19th century.
  • Tomato history (TAMU).
  • Harvested organ; fruit. Cherry Tomato, David Rhodes
  • Fruit is rich in vitamins A and C, calcium and potassium.
  • Fruit size ranges from 2 cm in diameter (cherry tomatoes) to over 15 cm (large-fruited "beafsteak" tomatoes).
  • Fruit color ranges from yellow to orange to deep red (the red color is conferred by accumulation of a carotenoid pigment, lycopene).
  • Fruit shape ranges from ovals to plum-shaped (Italian plum tomato), to pear-shaped (pear tomatoes).
  • Fruit flavor ranges from very sweet to highly acidic.
  • Grown under either greenhouse or field conditions.
  • Field-grown tomatoes are of two major types; fresh market and processing.
  • Greenhouse tomatoes are generally indeterminate and require trellising.
  • Varieties used for commercial fresh market production outdoors are determinate; much shorter in stature than the indeterminate types.
  • Determinate types are easier to harvest and have a more concentrated fruit maturation. Determinate types still benefit from staking to prevent fruit contact with the soil.
  • Fresh market varieties are usually started as transplants. Beds are often covered with black plastic mulch to promote earliness and suppress weeds, and plants are often supported with cages, stakes or trellises. Supported tomato plants produce higher quality fruit than unsupported plants.
  • Plants supported by stakes or trellises are often pruned; several or all of the branches up to the branch just below the first flower cluster are removed when the branches are a few inches in length. Pruned plants produce fewer but larger fruit than unpruned plants.
  • Fresh market tomatoes are hand-harvested. Blossom End Rot on Immature Tomato Fruit, David Rhodes
  • Processing tomato varieties have been developed with the following traits: determinate, dwarf habit, uniform fruit ripening, tough skins, a squarish shape, and high soluble solids.
  • Processing tomatoes are usually direct seeded.
  • Processing tomatoes are generally grown without trellising or staking, and are machine harvested.
  • About 75% of the total tomato crop is processed into juice, canned tomatoes, sauces, pastes, and catsup.
  • Optimum soil pH: 6.0 to 6.8.
  • Susceptible to calcium deficiency even when adequate levels of calcium are present in the soil. Calcium deficiency causes the disorder of blossom-end rot, and can occur as a result of inadequate or excessive watering, or excessive fertilization with an ammonium source.
  • A foliar spray of calcium nitrate (10 to 15 lb per 100 gallons of water) directly to the developing fruit may reduce the incidence of blossom-end rot.
  • Some varieties are less prone to blossom-end rot disorder than others.
  • In addition to promoting blossom-end rot, wide fluctuations in soil moisture may also promote fruit cracking in certain varieties.
  • The tomato fruit has characteristic stages of fruit ripeness; green (extreme left), mature green, breaker, pink, red, ripe red (extreme right).

    Stages of tomato fruit maturation, David Rhodes
  • Mature green tomato fruit is chilling sensitive and should not be stored at temperatures below 10 C. As the tomato fruit ripens it becomes less susceptible to chilling injury. At the pink stage tomatoes can be held at 5 C for 4 days without injury. When returned to 13 to 15 C pink fruit will complete ripening in 1 to 4 days.
  • In the fresh market industry the tomato fruit is often picked at the mature green or breaker stages for long-distance shipping, and is then subsequently ripened by treatment with the gas, ethylene (12 to 18 h at 20 C).
  • For processing tomatoes the ethylene-producing compound, ethephon or Ethrel, is applied prior to harvest when only 10% of the fruit is ripe; this accelerates and concentrates fruit-ripening and facilitates once-over machine harvest.
  • Major diseases of tomatoes in the Midwest: Symptoms of Bacterial Spot on Immature Tomato Fruit, David Rhodes
  • Major insect pests of tomatoes in the Midwest:
    Tobacco hornworm, characterized by 7 white stripes; David Rhodes

    (see: ID-56 ID-56: Midwest Vegetable Production Guide for Commercial Growers 2003 - Tomato (PURDUE) [pdf] for information on tomato varieties, transplants, ethephon application, spacing, cultural practices, fertilizing, and specific tomato disease, weed and insect control recommendations for Midwest tomato production)

    Sources of information:

  • Brust, G., Henne, R. Tomatoes. In "Vegetable Insect Management With Emphasis on the Midwest", (ed. R. Foster, B. Flood), Meister Publishing Co., Willoughby, Ohio, pp. 77-88 (1995).
  • Nonnecke, I.L. "Vegetable Production", Van Nostrand Reinhold, NY (1989).
  • Lorenz, O.A. Tomato. In "The Software Toolworks Multimedia Encyclopedia", Version 1.5, Grolier, Inc. (1992).
  • Phillips, R., Rix, M. "The Random House Book of Vegetables", Random House, NY (1993).
  • Kalloo, G. Tomato, Lycopersicon esculentum Miller. In "Genetic Improvement of Vegetable Crops", (ed. G. Kalloo, B.O. Bergh), Pergamon Press, Oxford, U.K., pp. 645-666 (1993).
  • Midwest Vegetable Production Guide for Commercial Growers, ID-56, eds. R. Foster, D. Egel, E. Maynard, R. Weinzierl, H. Taber, L.W. Jett, B. Hutchinson, Purdue University Cooperative Extension Service, 2003.
  • Madhavi, D.L., Salunkhe, D.K. Tomato. In "Handbook of Vegetable Science and Technology: Production, Composition, Storage, and Processing", (ed. D.K. Salunkhe, S.S. Kadam), Marcel Dekker, Inc., NY, pp. 171-201 (1998).

    www www.hort.purdue.edu
  • David Rhodes
    Department of Horticulture & Landscape Architecture
    Horticulture Building
    625 Agriculture Mall Drive
    Purdue University
    West Lafayette, IN 47907-2010
    Last Update: 01/21/09