Taking an environmentally sensitive approach to pest management
Few horticultural crops signal the arrival of autumn more so than pumpkin. This fall, millions of Americans will make an annual pilgrimage to a retail outlet to purchase a vegetable they (unfortunately) are very unlikely to eat. While many people throughout the world use pumpkin as a staple in their daily diet, in the United States this colorful member of the Cucurbitaceae (gourd) family is used primarily for decoration. Halloween and Thanksgiving just would not be complete without pumpkins to add a festive air to the observation of these two events. October is an appropriate month to take a closer look at this fall favorite.
Pumpkin derived its name from the Greek word “pepon” which, literally interpreted, means “large melon”. The French word for “pepon” was “pompon” and the English changed the latter to “pumpion”. American colonists are credited with changing “pumpion” to “pumpkin”, the name which still is associated with this vegetable.
Pumpkin is somewhat of a generic name assigned to several members of the genus Curcubita. They include C. maxima, C. moschata and C. pepo. The names pumpkin and winter squash commonly are used for all of these species also. However, most authorities place the large, orange fruit sold for autumn decoration in the species C. maxima, and assign winter squash as a common name to the other two species. Interestingly, the canned product sold for making pumpkin pies actually is C. moschata, a species of winter squash.
Archeological evidence suggests that pumpkins and winter squash are native to the Americas from the southwestern part of what is now the United States through Mexico and Central America and south into Peru, Ecuador and Colombia. Pumpkins have been cultivated since about 3500 B.C. rivaling it with maize (corn) as one of the oldest known crops in the western hemisphere. Native Americans are said to have roasted long strips of pumpkin on an open fire and then consumed them. They also dried pumpkin strips and wove them into mats.
Presumably, American colonists relied heavily on pumpkin as a food source as evidenced by this poem (circa 1630):
One way colonists are thought to have prepared pumpkins was to slice off their tops, remove the seeds and refill the inside with a mixture of milk, spices and honey. The resultant concoction was baked in hot ashes and is said to be the origin of our modern pumpkin pie.
Columbus was known to have taken pumpkin seeds back to Europe on one of his excursions. However, pumpkins are warm season vegetables that require a relative long growing season. Thus, they never have gained popularity in northern Europe and the British Isles where the summer temperatures are not conducive to their growth.
Today, pumpkins still are valuable as a food crop but are more widely used for their ornamental value. Brightly colored, orange pumpkins are a staple for fall decoration especially around Halloween when frightening faces are carved into them to form jack-o-lanterns. Although jack-o-lanterns have been carved by people for centuries, the use of pumpkins to make them is relatively new and originated in America.
Jack-o-lanterns originated in Ireland where, according to Irish myth, a notorious character by the name of “Stingy Jack” succeeded in tricking the devil on several occasions through the course of his life, much to the devil’s annoyance. Upon his death, Stingy Jack appeared at the gates of hell to learn his eternal fate. The devil, having been fooled by him on several prior occasions, refused to let him enter. Instead, he sent Jack off into the dark night with a burning lump of coal to guide his way. According to legend, Jack put the glowing coal into a hollowed out turnip and has been roaming the Earth ever since.
Immigrants arriving in America continued the tradition of making jack-o-lanterns but found pumpkins much easier to carve than turnips. The association of jack-o-lanterns with Halloween is related to the Celtic festival of Samhain, observed on October 31st–the Celtic equivalent to our New Year’s Eve. The Celts believed the spirits of the dead (including Stingy Jack) roamed the earth on that night.
Pumpkins are heat-loving plants and should not be planted until the soil has thoroughly warmed in the spring. Early June is a suggested planting date for most areas in Missouri. Select a location with good soil that is well-drained and has few perennial weeds. Avoid areas that have received herbicides the previous year aimed at broad-leaf weed control since these compound can carry over to the following year.
Pumpkins are vigorous growers and heavy feeders that require adequate nutrition to produce a good crop. Follow soil test recommendations or apply about 1000 pounds of a starter fertilizer such as 5-10-10 per acre (10 pounds per 100 feet of row) when preparing soil for planting. Later, when the vines start to “run” (reach a length of 12 - 15 inches) sidedress with 20 to 30 pounds of actual nitrogen and 60 to 100 pounds of actual potassium (K2O) per acre (one pound of 13-0-44 per 100 feet of row). The ideal soil pH for pumpkin production is between 6.0 and 6.5.
Spacing pumpkins depends upon variety. Most of the older, large-fruited varieties produce very vigorous vines that can spread up to 18 feet. Traditionally, these types are spaced 12 to 15 feet between rows and 2 to 4 feet between plants within the rows. Newer, semi-dwarf varieties can be planted in rows 9 to 12 feet apart with plants 2 feet apart within the rows. Dwarf pumpkins can be planted even more closely leaving only 6 to 8 feet between rows and 2 feet between plants within the rows. The use of black plastic mulch will both conserve moisture and help control weeds within the rows.
Because of their lush vegetative growth, pumpkins are prone to insect and disease infestation. Squash bug, squash vine borer, cucumber beetle and aphids are some of the more troublesome insects that attack pumpkins. Timely applications of pesticides labeled for these insects (e.g. endosulfan and carbaryl) can help to minimize damage. Monitoring insect populations by inspection or through the use of traps is essential for proper timing of pesticide applications.
Problematic diseases of pumpkins include powdery mildew, angular leaf spot, black rot, gummy stem blight, mosaic virus and bacterial wilt. Strict sanitation including the removal or turning under of all plant residue between crops is the first line of defense against disease infestation. Following that, preventative fungicides (e.g. chlorothalonil) are very effective in protecting pumpkins from disease problems caused by fungi.
Weeds tend to reduce both yield and quality of pumpkins by competing for sun, water and plant nutrients. Additional to the use of mulch, hand cultivation during the early stages of growth is essential for good weed control. Once the vines start to run, weed control becomes difficult unless herbicides are used. Trifluralin, clomazone and ethalfluralin are examples of herbicides that have been successfully used for weed control in pumpkins. With these or any other pesticides applied, always read and follow label directions.
Harvesting pumpkins at full maturity is essential for high quality and good storage life. Maturity occurs when the shell (rind) has completely hardened. Fruits destined for storage should be allowed to undergo a curing process after harvesting by exposing them for about two weeks to temperatures in the 75 to 85 degree F. range along with good air circulation. Avoid waiting until after a hard frost to harvest pumpkins since this will adversely affect storage. A portion of the stem (i.e., the “handle”) should be left attached to the pumpkin since this usually makes them more decorative.
As previously mentioned, pumpkins are a valuable food crop and an important part of the diet of many people worldwide. They are low in calories, fat, and sodium and high in fiber. A study by the USDA indicated that diets high in pumpkin as a fiber source tended to curb the appetite. The subjects in this study also absorbed less fat and calories from their food. Additionally, pumpkins are good sources of Vitamin A, Vitamin B, potassium, protein, and iron. A cup of cooked, mashed pumpkin contains only 49 calories.
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REVISED: August 29, 2013