Abstract
This publication addresses organic production techniques for winter squash, pumpkins, and gourds, including soil and fertilization, planting, weed management, insect pest management, diseases, harvest, curing and storing, and marketing.
This publication
contains references to enclosures that are available in hard
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Table of Contents
Introduction
Winter squash, pumpkins, and gourds all belong to the genus Cucurbita.
Four species—discernible by their stem structure—are
commonly grown in the United States. (1) Production
practices are essentially the same for all.
Cucurbita maxima has a short, corky, round stem and tends
to be more yellow than orange. The species includes several large
pumpkins and most winter squash (Hubbard, Buttercup, Banana, Mammoth,
and Turban).
Cucurbita pepo is usually recognized as the true pumpkin
and includes many pie, jack-o-lantern, and field pumpkins as well
as summer squash, acorn squash, and spaghetti squash. Varieties
within this group have hard, woody, distinctly furrowed stems. The
pumpkins have bright, deep orange skin.
The stems of Cucurbita moshata are deeply ridged, pentagonal,
and smooth. They enlarge but do not flare next to the fruit. A member
of this group is used for most of the canned pumpkin sold in this
country. Most varieties are tan and oblong. Cushaw, Winter Crookneck,
and Butternut squash are in this species.
Cucurbita mixta was once included with C. moschata,
but differs in flesh texture and has an enlarged corky stem. It
is primarily a processing squash.
Cucurbita species originated over 9,000 years ago in Central
and South America, the first of the triad of corn, beans, and squash
to be domesticated. Squash was grown primarily for its edible seeds,
because the flesh of these early types was bitter-tasting.
Long before Europeans set foot in the New World, native South Americans
cultivated improved varieties, seeds of which traveled north. Squash
and pumpkins became a mainstay for the early colonists, who had
many culinary and medicinal uses for them. The first pumpkin “pie”
was actually a pumpkin with its top cut off, seeds removed, and
cavity filled with a mixture of apples, sweetener, spices, and milk.
The top was replaced and the entire thing was baked.
Pumpkins have slowly faded from the culinary forefront, with the
sweet full-flavored squash becoming increasingly popular. Pumpkins
are now associated more with Halloween than with winter food supplies.
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General Production Information
Information on conventional production methods is available from
the Cooperative Extension Service in most states. Much of this information
is useful to organic growers, as well. However, information on organic
soil fertility, weed, insect, and disease management practices are
not so readily available.
Organic farmers rely heavily on crop rotations, crop residues,
animal manures, legumes, green manures, composts, and mineral-bearing
rock powders to feed the soil and supply plant nutrients. They manage
insects, weeds, and other pests with mechanical cultivation and
cultural, biological, and biorational controls. They do not use
conventional commercial fertilizers, synthetic pesticides, or synthetic
growth regulators. The ATTRA publication Organic Crop Production Overview is recommended to those seeking
a better understanding of the history, philosophy, and practices
of organic farming.
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Soil and Fertilization
Squashes prefer a well-drained sandy loam with high organic matter
and a pH of 6.0 to 6.5. The Cooperative Extension Service or a soil-testing
laboratory can provide nutrient recommendations based on soil tests.
Conventional production recommendations (when soil-test results
are not available) are to apply 50 pounds N, 100 pounds P2O5, and
100 pounds K2O per acre before planting, with two additional applications
of 25 pounds N and 80 pounds K per acre at 3 and 6 weeks. (2)
Should you wish to convert these standard recommendations to organic
fertilizer rates, visit the site from the University of Georgia Circular
853 How
to Convert an Inorganic Fertilizer Recommendation to an Organic
One. To obtain hard copies of Circular 853, contact:
University of Georgia Cooperative Extension
Agricultural Business Office
Rm. 203 Conner Hall
University of Georgia
Athens, GA 30602
706-542-8999
706-583-0236 FAX
Roberta Bunker, an organic gardener in Maine (1),
places a bushel of well-rotted manure and four shovelfuls of compost
under each hill. An old USDA Farmers’ Bulletin recommends
well-decomposed stable manure applied at the rate of 10 tons or
more per acre broadcast and plowed under in the fall. (3)
ATTRA has a number of publications
on soil and fertility that can help you choose and locate organic
nutrient sources and establish a sustainable fertility management
system suitable for cucurbits and other crops.
Many organic growers use a winter annual legume cover crop to supply
some of the nitrogen requirements. The enclosed articles on no-till
pumpkin production describe a system for managing winter annual
cover crops for increased soil health and weed suppression. The
system has many benefits, as well as several constraints. Pennsylvania
farmer Steve Groff, who practices and advocates no-till vegetable
production, offers a video showing how the system works for him.
(4) Though Groff is not an organic producer,
his information is highly relevant and can be readily adapted. For
more information on no-till options, see the ATTRA publications
Conservation
Tillage and Pursuing
Conservation Tillage for Organic Crop Production.
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Planting
Cucurbits are warm-season annuals, preferring 75° to 86°
F daytime and 64° F nighttime temperatures. The seeds germinate
most rapidly when the soil temperature is 86° F. Winter squash
and pumpkins can be direct-seeded as soon as the soil temperature
reaches 60° F. They need 90 to 120 frost-free days to reach
maturity. Plastic mulches of various colors can be used to increase
the soil temperature and speed early-season plant growth. See the
ATTRA publication Season
Extension Techniques for Market Gardeners for details on
plastic mulches.
Pumpkins and squashes, like other cucurbits, are not easy to transplant.
If you decide to start seeds in a greenhouse for later transplanting,
use paper or other fiber containers that can be easily peeled away
from the roots, or tapered pots so that plants can be easily slipped
out. Use one container for each seedling, so that it can be set
out with a minimum of root disturbance. Or start your plants in
peat pots that can be planted pot and all. In certified organic
production, organic potting mix must be used. See the ATTRA publications
Potting Mixes for
Certified Organic Production and Plug
and Transplant Production for Organic Systems.
Information about depth of seed placement and spacing is available
from seed dealers. In general, seeds are placed about 1-inch deep,
either in hills of several seeds, or in rows. If you are using a
hill system, plant three to five seeds per hill, then thin to one
to three plants per hill. The hills can be spaced as closely as
4 x 5 feet or as much as 8 x 12 feet apart. If you plant in rows,
perhaps with a mechanical seeder, 2 to 3 pounds of seed per acre
should be sufficient for achieving the recommended 3,000 to 4,000
plants per acre.
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Weed Management
Mechanical cultivation and hand hoeing before the plants begin
to vine are time-honored methods of weeding. Cultivation should
be shallow to avoid injuring shallow roots. The video Vegetable
Farmers and Their Weed Control Machines (5) introduces innovations that make mechanical
cultivation easier.
Mulches, either plastic or from plant residue, are used by many
growers to prevent weed growth. Enclosed is an article describing
plastic mulch and drip irrigation used for pumpkins. The no-till
system mentioned earlier is one way to grow a weed-suppressing mulch
of plant residues in place.
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Insect Pest Problems
Squash bugs (Anasa tristis) are the major pest for most squash
and pumpkin growers. Market gardener and author Steve Salt writes:
Year in and year out, . . . the Public Enemy
Number One of pumpkins (on my farm at least)—causing losses
greater than rots, frost, and drought combined—is the squash
bug. These pungently odoriferous gray-brown insects lay masses
of red-brown eggs on leaves and stems in early midsummer. The
eggs hatch into hordes of tiny pale gray nymphs which fan out
through the pumpkin patch, sucking sap and (some scientists speculate)
possibly injecting a poison into the plants. Plants attacked by
even a few squash-bug nymphs wither, and the leaves curl and turn
a crispy texture with a characteristic bronze color. Immature
fruits on affected plants cease development, and frequently rot
or fall prey to cucumber beetle predation. Plants fail to recover
even after the nymphs move on in search of fresh victims. Losses
can be severe; badly infested fields look like someone has gone
through the patch with a flame-thrower.
The ATTRA publication Squash
Bug and Squash Vine Borer: Organic Controls offers strategies for dealing
with this pest.
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Cucumber beetles are another insect pest to watch for. There are
several kinds, and they vary in importance around the country. The
striped cucumber beetle is about 3/16-inch long, greenish-yellow,
with three longitudinal black stripes. The spotted cucumber beetle
is the same color but with 12 black spots. These beetles feed on
young plants as they emerge and can decimate a planting. They also
spread bacterial wilt, a disease that can cause severe plant losses
later in the season. Row covers can provide a barrier to cucumber
beetles when the plants are young. (They must be removed when plants
begin to bloom so that insect pollinators can reach the blossoms.)
Natural enemies include soldier beetles, tachinid flies, brachonid
wasps, and bats, but they may not be effective in substantially
reducing beetle damage. A botanical insecticide, such as rotenone,
may be helpful if damage is intolerable. Research done by Cornell
University entomologist Michael Hoffmann has shown that fall
cultivation, if done while the beetles are still active, can cause
more than 40% mortality. (6)
Squash vine borers (Melittia cucurbitae) appear when vines begin
to run. The borer is a fat, 1-inch-long, brown-headed white caterpillar,
the larva of a ¾-inch-long moth with dark front wings, clear
hind wings, and a red abdomen. The moths lay single eggs in late
spring or early summer along the stem near the base of a vine. The
larvae emerge in about a week and bore holes to enter the stem.
Evidence of borer activity are the small hole and a pile of greenish
frass (excrement) beneath the hole. The vine wilts suddenly and
dies. Since damage occurs inside the stem, it is difficult to spot
and treat. For ways to deal with this pest, see the ATTRA publication
Squash Bug and Squash Vine Borer: Organic Controls.
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Diseases
Downy mildew, one of the most important foliar diseases of cucurbits,
is caused by the fungus Pseudoperonospora cubensis. It
thrives in damp weather when temperatures range between 45°
and 55° F for more than a month. It is more of a problem in
cooler areas than in warm areas. Symptoms first appear as patches
on the leaves that start out yellow, then become tan or brown with
white or gray downy fuzz underneath. As the disease worsens, the
patches turn sooty black. As the leaves die, the plants may also
shrivel and die. Fruit quantity and quality are reduced. To avoid
downy mildew, plant tolerant cultivars, grow vines with plenty of
space between them, spray vines with compost tea when conditions
are right for the disease to occur, and practice a three-year rotation.
For more details, see the ATTRA publications Downy
Mildew Control in Cucurbits and Notes
on Compost Teas.
Powdery mildew is another major foliar disease of cucurbits. Several
different fungi cause it. Symptoms are whitish, talcum-like growth
on both leaf surfaces and stems. Warm weather, coupled with high
humidity, rainfall, or dew, activates dormant spores that infect
the leaves. The disease is most severe when days are hot and nights
are cool. Older, fruit-bearing plants are affected first. Infected
leaves usually wither and die. In extreme cases, the entire vine
will die. To avoid powdery mildew plant resistant cultivars, control
insects, avoid overhead watering, spray vines with compost tea or
a baking soda solution, remove and destroy vines at the end of each
season, and rotate crops. See the ATTRA publication Use
of Baking Soda as a Fungicide for more information.
Black rot (on fruits) is also called gummy stem blight (on leaves
and stems) and is most common in the southern U.S. It is also found
in cooler regions, especially on winter squash and pumpkins. The
fungus Didymella bryoniae causes black rot. It lives on dry plant
material or in the soil, where it can survive for more than a year.
Free water on leaves for at least one hour is necessary for infection,
and further continuous leaf wetness is required for lesion expansion.
Fruits are infected either through wounds or by the extension of
leaf lesions. Black rot can cause loss of squashes and pumpkins
in storage. To avoid black rot, irrigation should be managed to
minimize free moisture on leaf surfaces, and a minimum two-year
rotation cycle is a must.
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Harvest, Curing and Storage
The enclosed article Harvest time crucial for winter squash
describes ways to judge ripeness of various types of winter squash.
If long term storage is anticipated, winter squash and pumpkins
should be cured for 7 to 10 days at 80° to 85° F. In general,
longest term storage is achieved at 50° F and 60% relative humidity.
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Marketing
Pumpkins and winter squash speak to us of Halloween and Thanksgiving.
Major consumers include children and adults seeking the perfect
pumpkin for a jack-o-lantern. You can be creative in meeting that
market. A harvest festival can bring customers to the farm to pick-their-own
pumpkin, participate in a face-cutting contest, or go through a
hay-bale maze. See the ATTRA publication Entertainment
Farming and Agri-Tourism for additional ideas. Both pumpkins
and squash are in demand as seasonal decorations in homes and businesses.
Thanksgiving pies, roasted seeds, and breads are mouthwatering culinary
uses.
The enclosures provide additional details on growing, harvesting,
storing, and marketing winter squash and pumpkins.
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References
- Bunker, Roberta. 1991. Winter squash
and pumpkins. Maine Organic Farmer & Gardener. November–December.
p. 19–20.
- Peet, Mary. No date. Squash,
Gourd, and Pumpkin: Production Practices. 1 p. Accessed online
2/19/2002.
- Anon. 1964. Growing Pumpkins and
Squashes. USDA Farmers’ Bulletin No. 2086. 27 p.
- Groff, Steve. No-Till Vegetables
(video). Available for $21.95 plus $3 shipping and handling from:
Cedar Meadow Farms
679 Hilldale Rd.
Holtwood, PA 17532
717-284-5154
sgroff@epix.net
- Vegetable Farmers and their Weed-Control
Machines (video). Filmed in New England on the farms of nine vegetable
growers. The cost of the 75- minute video is $12 plus $3.75 shipping
and handling. It can be ordered from:
NRAES
Cooperative Extension Service
152 Riley-Robb Hall
Ithaca, NY 14853-5701
607-255-7654
nraes@cornell.edu
- Hoffmann, Michael. 1998. Developing
sustainable management tactics for cucumber beetle in cucurbits.
Reports from the Field . Northeast Region SARE. December. 4 p.
Accessed online and updated 7/11/05
www.sare.org/reporting/report_viewer.asp?pn=ANE95-022&ry=1999&rf=1
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Enclosures
Bartsch, J.A. 1992. Storage of winter squash. Vegetable Notes.
University of Massachusetts. September. p. 5–6.
Blanchard, Chris. 2000. Harvest timing critical for winter squash.
Growing for Market. September. p. 1, 4–5.
Loy, Brent. 2001. Plastic mulch and drip can be used for pumpkins.
The Vegetable Grower News. April. p. 23, 27.
Morse, Ronald et al. 2001. No-Till Pumpkin Production: Principles
and Practices. Pennsylvania Marketing and Research Program. 16 p.
Morse, Ronald. 1998. Keys to Successful Production of Transplanted
Crops in High-Residue, No-Till Farming Systems. Arkansas Agricultural
Experiment Station Special Report 186. July. p. 79–82.
Richards, Keith. 1994. Growing pumpkins for a harvest festival.
Farming More Sustainably in the South. Southern Sustainable Agriculture
Working Group. p. 24–27.
Salt, Steve. 1997. The great pumpkin. Small Farm Today. October–November.
p. 24–28.
Smida, Jordanna. 2001. Pumpkins to Christmas trees. No-Till Farmer.
October. p. 14.
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Resources
Averre, C.W. et al. 1996. Compendium of Cucurbit Diseases. The
American Phytopathologcal Society. St. Paul, MN. 91 p.
Hoffmann, Michael P. and Anne C. Frodsham. 1993. Natural Enemies
of Vegetable Insect Pests. Cornell Cooperative Extension. 66 p.
Kuepper, George and Mardi Dodson. 2001. Companion Planting: Basic
Concepts and Resources. Horticulture Technical Note. NCAT/ATTRA,
Fayetteville, AR. 16 p.
Includes a detailed description of the Native American corn,
beans and squash planting system known as the three sisters.
Organic Pumpkin and Winter Squash Production
By Janet Bachmann
NCAT Agriculture Specialist
Cole Loeffler, HTML Production
CT 172
Slot 6
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