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Tomatoes (greenhouse)

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The tomato, Lycopersicon esculentum, is a part of the nightshade family. It is a warm-season crop that originated in the Americas and was taken to Europe by Spanish conquistadors in the sixteenth century.

Some believe the fruit might have been taken to Europe by Christopher Columbus himself as early as the fifteenth century. Botanically speaking, the tomato is a fruit but was deemed a vegetable in 1893 by the U.S. Supreme Court to clear up a tariff dispute.

Both field- and greenhouse-grown tomatoes for the fresh market are hand-picked, while most bound for processing are harvested by machine.

The world’s top producer of tomatoes is China, in both field-grown and greenhouse varieties. In North America, Canada rules the greenhouse market, followed by Mexico and the United States.

AVAILABILITY

CANADA MEXICO UNITED STATES OTHER INTERNATIONAL
Alberta
British Columbia
Ontario
Quebec
Baja*
Colima
Hidalgo
Jalisco
Michoacán
Querétaro
San Luis Potosí
Sinaloa
Sonora
Zacatecas
Arizona
California
Colorado
Florida
Illinois
Michigan
Ohio
Texas
Belgium
France
Israel
Netherlands
Spain
Turkey

*includes Baja California and Baja California Sur.
References: Asociatión Mexicana de Horticultura Protegida (AMHPAC); Gary Hickman, Cuesta Roble Consulting; Roberta Cook (formerly of University of California, Davis), Statistics Canada, USDA.

 

Types & Varieties
Tomatoes can be classified several ways but usually fall into determinate and indeterminate varieties. Determinate varieties grow to a certain height and produce fruit for one cycle; indeterminate varieties require staking and grow throughout the season. Commercially, both determinate and indeterminate varieties are used.

Cultivars for greenhouses tend to be specifically bred and of a heartier nature due to reductions (15 to 20%) in light and with some seeds tailored to geographic location. Target harvests can range from 25 to 45 pounds of fruit per plant during a 10- to 12-month growing season.

Greenhouse-grown, like open-field tomatoes, come in several shapes, sizes, and colors. Standard sizes include the most common, the round or globe, as well as cherry, grape/plum, or pear/teardrop cultivars.

Cherry tomatoes are small and range in size from one to two inches in diameter; beefsteak tomatoes are large, wide, and somewhat flat-looking.

Grape, plum, or pear tomatoes have smooth skin and are shaped as their names imply.

Colors are no longer limited to traditional red, there are also white, yellow/orange, green, brown, pink, and even purple/black.

The USDA categorizes tomatoes as greenhouse, fresh, cherry, or on-the-vine.

CULTIVATION

Most greenhouse tomatoes are grown in one- or two-season crop cycles, often depending on location. Growers in the southern portion of the United States avoid July and August, when sunlight and high temperatures make it cost-prohibitive to cool structures.

The opposite occurs in the U.S. Midwest and Canada during the harshest winter months (generally December to February), when it is difficult to maintain adequate light and heat.

Greenhouse tomatoes need at least 4 square feet per plant or about 10,000 plants per acre, as higher density—and the resultant loss of sunlight—can cause lower yields and promote disease when pest treatments cannot reach all foliage.

Plants can be grown in a variety of media, including soil-less (hydroponic or aeroponic), sand, bark, peat, perlite, rock wool, and straw to name a few.

Structures range from bags and nutrient film to plastic piping and trellises or troughs. Greenhouse tomatoes are collected by hand throughout the harvesting period.

Pests & Diseases
Pests and diseases are controlled through chemical or biological means (good bugs versus bad bugs), with special consideration given to organic production.

For the latter, some growers employ a hot water wash rather than pesticide applications; but most greenhouse growers utilize a biologic or integrated pest management program.

A number of insects pose a threat to greenhouse operations including aphids feeding on leaves, making them curl and become distorted; loopers, which also feed on leaves leaving ragged holes; and various whitefly species that feed on the underside of leaves turning them black.

Cutworms, hornworms, pinworms, leafminers, slugs, thrips, gnats, and moths can cause varying degrees of damage as well—though most are controlled by using mites, wasps, midges, beetles, and nematodes as biological control agents.

A number of diseases thrive in damp, humid conditions including botrytis grey mold (which turns leaves brown and causes molding of the stem and foliage), fusarium and verticillium wilt (which cause foliage to yellow and wilt).

Blossom-end rot will appear dark, flattened, or sunken areas on the blossom end of fruit. Other diseases include bacterial canker, ghost spot, blight, powdery mildew, and mosaic viruses.

Other problems and/or disorders affecting plants and yields can be caused by nutritional deficiencies or environmental fluctuations in temperature, humidity, light, water, etc.

Among the more common are cracking, splitting, catfacing (a malformation of the blossom end), scarring, blotchy ripening, green shoulder (greening near the top that never turns red), and sunscald or solar yellowing.

Storage & Packaging
Pink to firmly red fruit can be stored at temperatures of 50 to 55°F, while less mature tomatoes should be ripened at 70°F. For marketing, tomatoes are segregated by grade, color, and variety.

Greenhouse tomatoes are classed into U.S. No. 1 and U.S. No. 2 only (though most buyers will only buy U.S. No. 1 quality or better).

Tomatoes are subject to chilling injury and high humidity may encourage the growth of surface mold due to condensation. Ripening tomatoes do produce ethylene at a moderate rate, so storage or shipping with ethylene-sensitive commodities should be avoided.

References: Agricultural Marketing Resource Center, Mississippi State University Extension, Oregon State University, Statistics Canada, Texas A&M AgriLife Extension Service, University of Kentucky, USDA.

GRADES & GOOD ARRIVAL

Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.

U.S. Grade Standards Days Since Shipment % of Defects Allowed
10-5-1 5
4
3
2
1
15-8-3
14-8-3
13-7-2
11-6-1
10-5-1

Canadian good arrival guidelines (unless otherwise noted) are broken down into five parts as follows: maximum percentage of defects, maximum percentage of permanent defects, maximum percentage for any single permanent defect, maximum percentage for any single condition defect, and maximum for decay. Canadian destination guidelines are 10-5-5-10-3.

References: DRC, PACA, USDA.

INSPECTOR’S INSIGHTS

• The tolerance for softness and decay in tomatoes is only 1%
• Puffiness is scored as a defect when the open space in one or more locules materially detracts from the appearance
• Any unhealed skin break or cut is scored as a defect against the 5% tolerance for serious damage
• Mold on stems is scored as a defect, as damage, or as serious damage, depending on severity.

Source: Tom Yawman, International Produce Training, www.ipt.us.com.


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