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Pumpkins are a member of the cucurbit family (Cucurbitaceae), along with cantaloupe, cucumbers, squash, watermelon, and gourds.

Evidence of pumpkin consumption dates as far back as 7,000 to 13,000 B.C. to cliff dwelling Native Americans in the southwestern United States and in northern areas of South America such as Mexico and Peru. These tribes cultivated pumpkins before Europeans arrived and likely passed them on to the rest of the world, spreading to East Asia in the sixteenth or seventeenth centuries.

Seasonal Availability Chart

Types & Varieties
Since pumpkins share many traits with squash, there may be some overlap in identification across various regions of the United States.

In general, pumpkins have coarser flesh and a stronger flavor than most varieties of squash, and are broken down into four usage and size categories: giant, Jack O’ Lantern, pie, and ornamental.

Giant pumpkins range from 25 to as large as 1,000 pounds; Jack O’ Lanterns are usually ribbed fruits with smooth to bumpy orange skin ranging from about 10 to 25 pounds. These are typically used for carving during Halloween; they are also used to make pies and other dishes, for stock feed, and for their edible seeds.

Pie pumpkins—named for their most common use—are generally smaller and sweeter with smooth, firm, bright flesh ranging from about 5 to 10 pounds. Ornamental pumpkins are miniature, usually weighing less than a pound, and used primarily for decoration.

While pumpkins are typically thought of as being orange with smooth skin, varieties range from white or orange to green with either a bumpy or smooth texture, and from solid colored to striped.

CULTIVATION

Pumpkins require full-sun conditions with temperatures of at least 65 to 75°F—below 50 or above 95°F will slow growth. Soil texture must be coarse to medium to retain water and should be well-drained and aerated with a 5.8 to 6.6 pH level. Pumpkins will grow in sandy soil with ample irrigation as plants require constant moisture, particularly during blossoming and fruit set. Crop rotation with noncucurbits is ideal for disease and pest control.

Pumpkins may be field-seeded or transplanted and require approximately 4 months for full maturity, depending on the variety. Seeding requires from 2 to 4 pounds of seed per acre. Spacing depends on type (bush, semi-bush/vining, or vining) for anywhere from 600 to 3,000 plants per acre. Plants require from 5 to 12 feet between rows with 30 to 40 inches between plants. The large-leaved, spreading plants become competitive with weeds once they begin to mature.

Pumpkins develop both male and female flowers on the same plant and require honeybees for pollination. Particular care must be used when applying chemicals to the crop to avoid harming bees. Plants are pollinated at different times, requiring multiple harvests throughout the season.

As plants grow and develop fruit, pruning back to only two pumpkins per plant produces larger fruit. Mature fruit must be harvested before a hard freeze, though a light frost can be tolerated. Fruit color is often the best indicator of maturity.

Pumpkins are hand-harvested and prone to damage from rough handling. Cuts and bruises are entry points for pests and disease though small blemishes will heal during curing. Pumpkins are harvested by cutting from the vine, leaving an inch or more attached to the fruit. Pumpkins are usually graded in the field and loaded into trailers or bins lined with straw or some other cushioning material to prevent injury.

Pests & Diseases
A host of insects can play havoc with development and growth. Many favor excess moisture and cool conditions: beetles affect stems, leaves, and flowers; thrips, aphids, and melonworms go after leaves; cutworms attack below the surface and pickleworms bore into the fruit. Other pests include grasshoppers, leaf hoppers, leafminers, nematodes, root maggots, seed corn maggots, spider mites, squash bugs, squash vine borers, stink bugs, whiteflies, and wireworms.

Fungus-based diseases can be carried by wind, rain, or infected seeds, soil, or machinery. Excess or extended periods of rain will increase the likelihood of alternaria leaf spot, anthracnose, gummy stem blight, target spot, belly rot, and crown rot. Each of these diseases can cause spots, lesions, or cracks in the fruit. Powdery and downy mildew are common threats and caused by airborne fungi. The former thrives in dry, hot conditions while the latter loves wet, cool weather. Both cause discoloration of leaves and molding. Some new cultivars are resistant to powdery mildew.

Angular leaf spot and fruit blotch are bacteria-based diseases spread by infected seeds or debris left after harvest. Both cause spots and lesions on leaf margins and surfaces. Angular leaf spot worsens in wet, warm conditions. Mosaic is caused by any one of several viruses, spread by aphids. Symptoms include mottling and distortion or appear as chemically-induced damage. Other diseases include bacterial wilt, fusarium crown, and various types of blight.

Storage & Packaging
Fruit is cured at 70 to 85% relative humidity at 80 to 85°F for 10 to 20 days. Ideal post-curing storage is in a cool, dry environment between 50 to 60°F with good air circulation. Pumpkins are best stored in a single layer rather than stacked to prevent decay. Properly stored pumpkins will keep for 2 to 3 months.

References: PennState Extension, Purdue University Extension, University of Florida/IFAS Extension, University of Georgia Extension, University of Illinois Extension.

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 Optimum Transit Temp. (°F)
10-2 5
4
3
2
1
15-4
14-4
13-3
11-2
10-2
50-55°

There are no good arrival guidelines for this commodity specific to Canada; U.S. guidelines apply to shipments unless otherwise agreed by contract.

References: DRC, PACA, USDA.

INSPECTOR’S INSIGHTS

• Worm holes are scored as a defect when unhealed or if more than 2 are found in a winter squash or pumpkin
• There is no requirement in the U.S. No. 1 grade for a pumpkin to have its stem attached
• Score dry rot as a defect when affecting an area of more than 1 inch in diameter on a 10-pound specimen.

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


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