PUMPKIN Cucurbita spp.

FAMILY CHARACTERISTICS
    The vegetable species of Cucurbitaceae (“vine crops”) are similar in growth and culture and contribute significant amounts of vitamins and minerals to our diet. This family contains approximately 114 genera and 500 species of monoecious or dioecious herbs and erect shrubs. They are warm season annuals, thriving in hot and humid weather. Most have spreading growth habit and tendrils at the leaf axis. The leaves are alternate, simple and palmately lobed or palmately compound with 3 or more leaflets. The flowers are generally yellow in color and unisexual. Male and female flowers may be born on the same or different plants. The corolla of the flower is often large and showy, generally lasting a day or less. The female flower contains an ovary that is inferior, usually with a single locule with 1 to 3 placentas. Ovules and seeds vary from one to many in each fruit. The male flower has 1 to 5 stamens with 3 being average. Botanically, the fruit is a pepo, a fruit type in which the ovary wall is fused with the receptacle tissue to form a hard rind.
    The uses of the vine crops range from fresh desserts and salads (melon, watermelon, cucumber) to boiled or baked vegetables, utilizing immature fruit (summer squash) or hardened mature fruit (winter squash), to pies (mature squash and pumpkin), pickles (cucumber and watermelon rind), snack food (pumpkin and squash seeds) and as ornaments such as birdhouses (gourds).
    The bottle gourd which was used as a container for early man was one of the earliest cultivated plants with a documented prehistory in both the old and new worlds. As an ornamental, the Cucurbitaceae is of minor importance. Cucurbita pepo represents most of the ornamental gourds.
    Breeding tests have indicated that there is little or no spontaneous hybridization between species of either cucumis or cucurbita. Cultivars of different types but within the same species can cross-fertilize; for example, pumpkins, summer squash, and some gourds are interfertile. Growers saving seeds must maintain purity by isolating one cultivar from another. Although isolation is needed for seed purity, there is no effect of cross-pollination on the flesh quality of the resulting fruit.
    Other family members include:
        Benincasa hispida L.; Uax Gourd
        Citrullus lunatus (Thung.) Mansf .; Watermelon
        Citrullus lunatus var. citroides (Bailey) Mansf.; Citron, Preserving Melon
        Cucumis anguria L.; West Indian Gherkin
        Cucumis melo L. (Chito group); Mango Melon, Garden Lemon
        Cucumis melo L. (Conomon group); Melon, Oriental Pickling Melon
        Cucumis melo L. (Flexuosus group); Armonian Cucumber, Japanese Cucumber, Uri
        Cucumis melo L. (Inodorus group); Melon, Muskmelon, Winter Melon
        Cucumis melo L. (Reticulatus group); Melon, Muskmelon, Cantaloupe
        Cucurbita maxima Dutch.; Winter Squash, Pumpkin
        Cucurbita mixta Pang.; Pumpkin
        Cucurbita moschata Poir.; Winter Squash, Pumpkin
        Cucurbita pepo L.; Winter Squash, Marrow, Summer Squash, Pumpkin
        Cucumis sativus L.; Cucumber
        Lagenaria siceraria (Mol.) Standl.; Bottle Gourd
        Luffa acutangula Roxb.; Angled Loofah
        Luffa cylindrica Roem.; Smooth Loofah
        Momordica charantia L.; Bitter Gourd, Balsam Pear
        Sechium edile S.W.; Chayote
        Telfairia spp.; Oyster Nut
        Trichosanthes anquina L.; Snake Gourd

CROP HISTORY AND DEVELOPMENT
    Pumpkin comes from the Greek “pepon” (large melon), the French converted the word to popon which sounded like pimpon and was changed to pumpion. American colonists changed the “ion” to “kin” giving rise to pumpkin. Pompion means “eaten cooked by the sun” or when ripe.
    The 25-26 species of cucurbita are native to the Americas, most from North America.
    C. maxima  is the only cultivated species domesticated in South America. Each variety has a different history and therefore must be discussed separately.
    Cucurbita pepo L. is native to Mexico. This species was spread over northern Mexico and the southwestern U.S. by Columbus.
    Cucurbita mixta was first described in literature from Mexico and central America in the 1920’s. Most of the evidence proves that C. mixta is North American in origin, spread over the southwestern U.S. prior to 1492.
    Cucurbita moschata was widely distributed though out the North and South Americas before Columbus.
    Cucurbita maxima is the only species which originated in South America. Europeans arrived in the New World with C. maxima.
    At the time of the discovery of America, C. pepo was under cultivation from Canada to Guatemala. C. moschata was likewise grown but in a more restricted warmer area from Arizona to northern South America. C. maxima at the time was confined to northern Chile and Argentina, Bolivia, and Peru. All North American tribes grew Curcurbita spp. of diversified types as staple food items.
    Pumpkins were a major staple for Native Americans as well as maize, beans, and squash. They were then introduced to the colonists. The colonists turned the Indian's pumpkin soup into other more palatable products. Soon they were making pumpkin pie and dried pumpkin chips. Both Indians and colonists used pumpkins to treat bladder problems and alleviate pain, while seed were used to remove freckles.
    In the U.S., seeds usually are discarded, although pumpkin seeds, roasted and salted provide a nutritious snack. A “naked seed” mutant in which seeds lack the normal tough seed coat, has been introduced in some cultivars of pumpkin and squash. Such cultivars, listed as edible seeded, provide an excellent source of protein (34% of seed weight) and fat (46%) in addition to the nutritional value of the fruit flesh.

PLANT CHARACTERISTICS
    Root Systems  Root systems of all cucurbits are very similar. Most root systems are extensive but shallow. Pumpkins have a tap root which extend to a depth of 6’ with 6-10 laterals reaching out 5-15 feet. These laterals are branched with a fine fibrous root system which reaches well through the upper three feet of soil and down (to some extent) into the three to four foot layer.

Stem  The stems of genus Cucurbita usually help to identify the variety:  C. pepo has a hard and angular stem usually with five angles.  C. moschata is long, slender, and columnar also with five angles.  C. mixta is hard and five angled.  C. maxima has a soft and round stem. All of the stems have 3-8 branches at the nodes  near the main axis.      Leaves  The leaves of Cucurbita are simple and 3-5 lobed. Lobe depth changes with variety. C. pepo has harsh textured leaves whereas C. maxima, C. mixta, and C. moschata are soft textured.

Flowers Cucurbita plants have monoecious flowers that are bright yellow. Peduncle morphology helps in identifying the varieties. C. pepo has a 5-8 ridged peduncle that is deeply furrowed. C. maxima has a cylindrical peduncle without ridges. C. moschata have a five-ridged peduncle that flares at fruit attachment point. C. mixta has a five-angled peduncle that is round and slightly flared at the fruit attachment point. (flower photos provided by www.acesag.auburn.edu)

Female flower

Male Flower

Fruit  Fruit may be very large or small, but are grown to the hard shell mature stage, and those used as squash have very fine textured flesh. Cucurbita pepo includes summer squash, many pie, Jack-o-lantern, and field pumpkins, the baked cultivars ‘Acorn’ or ‘Tablequeen’, and most ornamental gourds. Fruit shape and colors and stage of harvest maturity vary widely among cultivars. Pumpkins are grown to maturity for use as Jack-o-lanterns or as pie ingredients and have a stringy coarse flesh. Cucurbita moschata, is used as a winter squash or pumpkin. C. mixta was once included within C. moschata, but there are some taxonomic an quality differences that distinguish them. C. mixta has an angular peduncle, like C. moschata, but it is enlarged by corky growth, and there are differences in seed margins and flesh texture. C. maxima includes fruit that are elliptical and tapering to a curved stem end. Fruits may also appear turban shaped. The fruit flesh is a fine grain texture.

Seed  There are numerous seeds in the fruit. Most seeds are plump and tan or soft white. They are all covered with a testa that serves as a protectant around the seed. They are also an excellent source of protein and fat.

Pumpkin seed

Seeds

PROPAGATION METHODS
    Overview  The main propagation method for pumpkins is direct seeding into the field. Most of the cucurbits are propagated this way, due to the inexpensive seeds and the difficulty in rooting transplants.
    Direct Seeding There are 10 pumpkin seeds in a gram, 200 in an ounce, and 3200 in a pound. The minimum official federal germination percent is 75%. Usually about 4 pounds of seed per acre are needed. The planting distance in a row is 36” to 60” and 12” to 96” between the rows. The seeds should be planted at a depth of 1” and allowed 7 days to germinate. Most cultivars are planted with multiple seeds to ensure a strong stand. Thinning may be necessary. Seeds should be sown after all danger of frost is past. C. maxima and C. pepo are slightly more cold tolerant, but no cucurbita can withstand frost.
Seed germination:

Minimum	Optimum Range	Optimum	Maximum
60°F	70-90°F	90°F	100°F

    Transplants  Cultivars do not transplant well. This is only done when the grower is trying to beat the market. The method is also more expensive than direct seeding. The transplants are fairly expensive. The seeds are generally planted 5-7 weeks prior to transplanting. The entire root system must be transplanted to the field. Any root damage will disturb the growth of the plant.

CULTURAL PRACTICES

Overview Pumpkins are grown both for fresh market and processing. Most of these cucurbit farms are found in the northern and central regions of the U.S., although cucurbits tend to adapt well to all climates. The important states that grow pumpkins are Illinois, New Jersey, California, and Indiana. Due to low capital investment and wide adaptability of the crop, acreage may vary widely from year to year.      Soil Requirements Most cucurbits can be planted on a wide variety of well drained soils, high in organic matter. Light textured soils are preferred in northern areas, since they warm quickly to 59°F, the minimum temperature for germination. The optimum soil pH should be 5.5-6.8.

    Temperature and Photoperiod  Pumpkins are warm season annuals, preferring 75-86°F daytime and 64°F night temperatures. This crop will not tolerate frost. Growth is also terminated when the soil temperature reaches 100°F.
    Flowering is photoperiod dependent. Male flowers appear when there are long hot days. Delay in female flower expression is thought to occur due to hastened maturation of the staminate flowers.
    Irrigation Flooding method is not used because of the increased probability of fruit rot. This happens because of surface moisture. Trickle irrigation is the most effective method when incorporating a plastic mulch. This method reduces weed control and lowers the risk of disease.
    Weed Control  Due to its root system, pumpkins compete well with weeds. To control weeds, cultivation may be used up until the time of vine spreading. This cultivation should be shallow so not to harm the shallow roots. Select and use herbicides according to state regulations and recommendations.

INSECTS
    The insects common to cucurbits are aphids, cucumber beetle, pickleworm, leafhopper and spider mites. In addition stem bores and squash bugs often cause substantial losses. The main insects to be concerned with are squash bugs and stem borers and three types of cucumber beetles.
        Banded cucumber beetle: light green bug with 3 black stripes
        Spotted cucumber beetle: greenish-yellow with 12 irregular black spots on back
        Striped cucumber beetle: these are yellow with 3 black stripes
    The adult squash bug is brownish-black, flat backed, 5/8 inch long, and lays its eggs on the underside of leaves, usually in rows at a right angle. When the eggs hatch, brightly colored nymphs appear which then proceed to feed on the plant sap. Squash bugs can kill small plants and can cause leaves to wilt and die.
    Squash vine borers can be very destructive. The first symptom to look for is wilting of the vine. The squash vine borer is wasp like with copper-green fore wing and reddish-orange, black abdomens. The insect over winters in the soil as a larva or pupa. The borer burrows into a stem, then hollows it out, leaving a slimy frass. After over wintering it emerges as a moth (wasp like).
    The moth lays eggs on the basal portion of the stem, and in 1 to 2 weeks borers emerge and penetrate the stem. Control is difficult, but sprays applied during egg laying and hatching are recommended.
    Pickleworms infect the fruit, stem, and leaves. They are yellowish-brown on the wings and have hair-like scales on their abdomen.
    Other pests that might be a problem include flea beetles, melon leaf hopper, leafminer, thrips, and cutworms. In addition to feeding damage, cucumber beetles spread virus and bacterial wilt, while leaf hopper transmits curly top virus.
    Sanitation, good cultural practices and crop rotation will all aid in insect control.

DISEASES
    Angular leaf spot  Causal organism: Pseudomonas lachrymans Carsner. The bacteria is a rod with 1-5 polar flagella, forming capsules and green fluorescent pigment in culture. Circular, smooth, glistening, transparent, white colonies form on beef peptone agar.
    Symptom: The disease appears on leaves, stems, and fruits as small water soaked spots. On leaves they enlarge up to about 3 mm in diameter, becoming tan on the upper surface and gummy or shiny on the lower surface and assuming an angular shape as the lesion in delimited by veins. The necrotic centers of leaf spots may drop out. On stems, petioles and fruits, the water soaked  spots are covered with a white crusty bacterial exudates. As fruits begin to mature, brown lesions in the fleshy tissue beneath the rind develop, and the discoloration continues along the vascular system which extends to the seeds.
    Bacterial Wilt Causal organism: Erwinia tracheiphila Holland. The bacteria is a motile rod with 4 to 8 peritrichous flagella. Capsules are formed. Agar colonies are internally resticulated, small, and circular, smooth, glistening, white and viscid.
    Symptoms: The first signs of wilt usually appear on individual leaves as dark green patches which become flaccid in sunny weather. As the disease progresses, more leaves wilt and eventually an entire branch is affected. The wilting then becomes permanent, and the leaves and vines shrivel and die. Occasionally an exudate on fruit is visible. When wilted stems are cross-sectioned, the viscid, sticky bacterial matrix exudes from the bundles and may be drawn out in strands of 1 inch or more. This feature is used as a means of diagnosis. Disease over winters in the bodies of adult cucumber beetles.
    Blossom Blight Causal organism: Choanephora cucurbitarum  Thaxt. A member of the family Choanephoraceae of the Phycomycetes. The fungus produces both conidia and sporangia spores.
    Symptoms: The disease is of importance as a fruit rot of squash and has been observed on other cucurbits.  The disease starts as a blossom blight. As the blossoms fade after opening, they are covered with a white, dense growth of the fungus, consisting chiefly of immature conidiophores. The conidial heads develop promptly, becoming purple-black at maturity. The organism invades young fruit and causes them to decay and die. In larger fruit a rapid, soft, watery rot occurs, the tissue becomes covered with sporgangia. The damage is chiefly on fruit in the field.
    Scab Causal organism: Cladosporium cucumelinum A fungal pathogen. The mycellum is septate, branching, hyaline when young turning greenish to black with age. Conidia are oblong, colored, mostly continuous, some one-septate.
    Symptoms: Appears in midsummer on leaves as small, roughly circular to angular spots which are water soaked, brownish and sometimes covered with exudates. Under continuous high humidity, sporulation occurs on the surface in the form of an olivacous mold. The greatest damage is to the fruit. Early in development of the fruit spot, a gummy brown exudate appears on the surface, and the crater-like spot grows, the surface tissue sinks, and the exudates may dry down in the form of large brown bead. When the fruits are infected after they reach full size, the host reacts by corking out the infected portion and forming a tan, shallow, scab.
    Mosaic Virus

Mosaic virus - fruit

Mosaic virus - leaves

Mosaic virus - leaves

The approximate time from planting to market maturity under optimum growing conditions should be for an early variety 100 days and for a late variety 120 days. The approximate time from pollination to market maturity under warm growing conditions should be 80-90 days for 'Connecticut Field', 90-110 for 'Dickinson', and 65-75 days for 'Small Sugar'.      Yields are highly variable and little data is available. Pumpkin have a similar  yield as winter squash which is 40,000 lb/acre. Pumpkins are harvested at physiological maturity. Usually the fruits are left on the vine until it dies. They should be harvested before frost. Pumpkins are usually harvested with a piece of the stem attached to assure better keeping quality and reduce water loss. Harvesting is usually done all at once.