Pumpkin and Squash Production
Table of Contents
- Introduction
- Climatic Requirements
- Soil and Fertility
- Planting and Spacing
- Weed Control
- Bees and Pollination
- Growth and Development
- Pumpkin and Squash Classification
- Insects and Diseases
- Harvesting
- Curing and Storing
- Yield Potential and Marketing
- Related Links
Introduction
Pumpkin and squash are important sources of income for many growers in
Ontario. Halloween now has a huge public following and is second only
to Christmas in decorative spending.
Consequently pumpkin production has increased significantly. There is
certainly a great deal of eye appeal for both pumpkin and squash products
(Figure 1)
Figure
1. Pumpkins offer high visual impact
in the market place.
Climatic Requirements
All cucurbits are warm-season crops. They grow best during hot weather
and cannot tolerate frost. Seeds will germinate at 15°C (60°F),
but germinate best at 29-32°C (85°F-90°F). Pumpkins and squashes
grow best at temperatures of 23-29°C (75°F-85°F) day and 15°C-21°C
(60°-70°F) night. Growth virtually stops at temperatures below
10°C (50°F) and the plants may be severely injured and maturity
delayed by temperatures below 5°C. (40°F) for several days.
Plants are usually killed by one hour or more of frost (temperature below
0°C, 32°F). Therefore, plant cucurbits in the field when soil
temperatures are high enough for good germination and all chance of frost
has passed. For early summer squash production, plastic mulch and/or row
covers will raise soil temperatures and provide some frost protection.
Low temperatures also have an adverse effect on flowering and fruit set.
Cucurbits are monoecious plants - that is, each plant produces both male
and female flowers. Normally, several male flowers form before female
flowers develop. During periods of cool temperatures (below 22°C,
70°F) most pumpkin and squash cultivars respond by producing primarily
male flowers. Male flowers do not form fruit. By contrast some cultivars
of summer squash appear to form mostly female flowers in response to cool
temperatures. Without male flowers to provide pollen, however, the female
flowers do not form fruit. (Figures 2, 3 and 4).
Figure 2. Male (left) and female (right) blossoms.
Figure 3. Developing fruit on female blossom, note swollen
ovary on 1 day-old flower.
Figure 4. Male blossoms (at each node) do not form fruit,
female blossom (far left) has been pollinated and is forming fruit.
Pumpkins and squashes are relatively deeply rooted (1.2-1.8 m; 4-6 ft)
and can tolerate dry conditions fairly well. However, extended dry periods
will result in poor fruit set and/or poor fruit development and size.
Plants tolerate wet conditions fairly well, but foliar diseases and fruit
rots increase. Plants also form adventitious roots at the notes (Figure
3) and help with water uptake.
Summer squashes are especially susceptible to drought because the fruit
develop and are harvested within a few days of pollination. Lack of sufficient
moisture often results in poor or irregular fruit development.
Pumpkins and squashes are usually grown without irrigation, but is a
great benefit if available. If irrigation is available, apply 2.5-3.75
cm (1-1½ in.) of water per week during flowering and fruit development.
Summer squashes usually benefit from regular irrigation throughout production.
Soil and Fertility
Pumpkins and squashes grow well on most well-drained soils. Sandy loams
are ideal. They also grow well on clay soils, but harvest is difficult
when soils are wet and the fruit often become dirty and difficult to clean.
Avoid production on low-lying or muck fields where plants are subject
to late spring or early fall frosts.
Cucurbits are good rotational crops with other vegetables. Because they
are usually grown for fall harvest, they can be planted in late May or
early June, and thus fit well into a planting schedule.
Presently, OMAFRA recommendations suggest up to 110 kg of nitrogen/ha
for pumpkin and squash whereby 65 kg of N is applied preplant broadcast,
with the remainder applied as a side-dress just prior to vine-run.
Planting and Spacing
Seed pumpkins and squashes with corn planters, using plates designed
specifically for these crops, or with vacuum seeders. Plant seed 2.5-3.75
cm (1-1½ in.) deep in moist soil.
Traditionally, medium-vined squashes and pumpkins are planted in rows
2-2.5 m (6-8 ft) apart, with plants spaced 0.5-0.6 m (1½-2 ft)
apart in rows. However, many growers use a 2 m X 2 m (6 ft X 6 ft) spacing
to allow for cross-cultivation. Where late season application of pesticides
is anticipated, leave spray and harvest aisles.
For larger varieties with fruit-size expectations of 9 kg (20 lbs) or
more, plants require a minimum of 3-3.6 m2 (35-40 ft2) each. Over-crowding
stresses plants, creating smaller fruit size. One hundred square feet
per plant may seem excessive, however, evidence suggests this is preferable.
In addition to fruit set problems, close spacing causes vine growth to
become 'airborne' - meaning that vines that would normally root in the
soil at the nodes will not be able to do so as the vine growth is not
situated along the soil surface were it belongs.
The amount of seed needed per acre varies with type, cultivar and spacing.
Large seeded cultivars (most pumpkins and winter squashes) require 0.5-1
kg (1-2 lb) of seed/acre. Note: For larger sized varieties, there are
approximately 6,600 seeds/kg (3000 seeds/lb).
Weed Control
Control weeds through frequent, shallow cultivation. Although pumpkins
and squash are deep-rooted, most roots are near the surface. Deep cultivation
is very harmful, destroying many of the fine roots near the soil surface.
Hand-weeding and hoeing is usually required. As the plants cover the ground,
they shade out many weeds.
Herbicides also help control weeds. However, there are currently limited
choices available for pumpkins and squash. For more details, see OMAFRA Publication 363,Vegetable Production Recommendations, or Publication 75,
Guide to Weed Control
Bees and Pollination
Bees are an essential part of the production of all vine crops. Wild
bees and other insects are normally sufficient to pollinate small fields.
However, where fields exceed 1 - 2 acres, bring in beehives for pollination.
One hive is needed for every 2 - 3 acres of pumpkins and squash.
Place hives in protected areas at edges of fields. Since bees normally
forage as close to the hive as possible, usually within ¼ mile,
place hives around the field to obtain more complete pollination of large
fields.
Blossom density for squashes and pumpkins is low. Therefore these crops
are not very attractive to bees. In addition, each cucurbit flower has
to be visited at least 15 times for complete pollination. Incomplete pollination
results in small and misshapen fruit. To improve the success of pollination,
place bees in fields 3 - 5 days after the first blossoms appear - at that
time about 10 - 15% of the plants should have open female flowers. Because
they are unaccustomed to the area, the bees will forage close to the hive
and will not stray into more attractive crops further away.
Growth and Development
Q - How many fruit (pumpkins) can be expected from a plant?
Although pumpkin plants produce a profusion of flowers throughout the
life of the plant, and starting very early in the plants development,
only 1 or 2 pumpkins per plant develop to any size. This varies depending
on the type and variety of pumpkin grown.
The bush or semi-bush pumpkin (e.g. Spirit) yields more than the traditional
type vines, such as Connecticut Field or Howden. However, as a rule of
thumb, and as a general guide to predicting yields, expect only about
1 to 1.5 pumpkins per vine.
Thus, if pumpkins were seeded and thinned to a population of 2,900 plants
to the acre (5 ft row centres, 3 ft within the row), then yields should
range up to about 4000 pumpkins per acre; an alternate spacing of 8 ft
by 2 ft will give about the same yield. The old traditional spacing on
a 6 ft square (1,210 plants/ac) would only yield about 1,800 fruit.
Miniature pumpkins, such as 'Baby Boo', 'Sweetie Pie', 'Jack-Be-Little'
and 'Munchkin', can easily yield 12-15 fruit per plant.
Never predict yields by the numbers of blossoms present, but
only by the fruit visible!
Q - If there are so many blossoms on any one vine throughout
the season, why are there not more fruit per plant?
All pumpkins and squash produce both male and female flowers separately
on the same plant (monoecious sex expression). These flowers originate
from the axils of the nodes. First, the male flowers form and bloom, allowing
pollen to be available as soon as the first female blossom appears.
The order and numbers in which these flowers appear vary somewhat as
to the time of year, the stage of plant development and the number of
fruit already pollinated and beginning to size. Developing fruit temporarily
reduces the occurrence of female blossoms further down the vine.
Pumpkins and squash are relatively insensitive to photoperiod (length
of day) during the summer season.
Female blossoms are short-lived. Female blossoms of pumpkins and squash
open first thing in the morning and close a few hours later (24 hours
at the most), never to re-open again. If these blossoms are not pollinated
they abort and fall off the plant. Generally, the female blossom is open
from about 10:00 a.m. to about 3:00 p.m.
Male flowers occur on the vine first. There are typically 10 male blossoms
for every female flower. Bees do not prefer one type (male or female)
over another, so make sure there are sufficient pollinators to do the
job. As well, the proportion of male blossoms usually increases when plants
are under stress.
The likelihood of a flower being pollinated depends upon the number of
bees present and the number of visits to that flower. If the weather is
poor (cold or wet) then there is almost no chance that flowers will be
satisfactorily pollinated.
Q - How do these vines grow and where do the flowers occur on
the plant?
Pumpkin plant growth is either: a) vining (trailing) or b) semi-erect
(bush-like). Bush varieties have shorter internodes (distance between
leaves), and lack tendrils. The trailing varieties may have between 3-8
lateral branches each arising from a separate node (point of leaf attachment).
Vine growth on the trailing types can be very vigourous with stem lengths
totally over 140 ft in some instances, and with up to about 450 leaves
in a 4 month growing season!
The yellow flowers occur singly in the axils of the leaves. In trailing
varieties, the staminate (male) flowers occur near the center of the vine
on long, slender stems; the pistillate (female) flowers occur on short,
ridged stems, further 'down' the vine than the male flowers. In bushy
types, the pistillate flowers occur near the base of the plant.
Q - How can the size of pumpkins be improved?
Water, temperature, insects and disease, pollination, fertility, soil
type, plant population, variety (genetics), weeds all influence the size
of crop.
Q - How important is it to keep the vine growing late into the
season?
For fruit to grow it must continue to receive nourishment from the mother
plant. If the vine dies prematurely, from powdery mildew or an early frost,
for example, then any further growth of that fruit will be halted.
However, if the fruit is already physiologically mature it will continue
to ripen by turning orange but without increasing in size. 'Mature' green
fruit (showing no colour change), that are not physiologically mature,
will not turn orange.
Q - Will earlier seeding or using transplants increase yield?
Generally, no. Usually there are only 1-2 pumpkins per plant. As fruit
begin to develop, there is a tendency for less female flowers to be produced
by the plant. If you seed during the last week of May and up to the 2nd
week in June, fruit usually grows to its full size, e.g. 15-20 lbs for
varieties such as 'Connecticut Field' and 'Howden'.
Pumpkins are a sub-tropical crop and respond to a longer growing season.
However, since the market for this crop is so late, there is little need
to hasten its planting.
In fact, in southwestern Ontario, pumpkins usually ripen so early that
it often causes concern as to the shelf life of these fruit. Therefore,
waiting until all risk of frost is past and soil temperatures have warmed
up allows for maximum plant stands. This should also allow the necessary
'window' for the seeding to take place in a moist soil.
In addition, later plantings tend to miss the first generation of seed
corn maggots and germinate before the 2nd generation arrives. However,
where heavy applications of manure have been applied previously, there
is a good chance that various maggots may cause seedling injury, as manure
attracts these egg-laying insects.
Q - What can be done to increase the length of the handle (stem
or peduncle), and to make the fruit a brighter orange?
Nothing, other than choosing a variety that exhibits those characteristics.
These factors are predetermined genetically and nothing in the line of
fertilizers or cultural practices will change this. This is also the case
when it comes to the degree of ribbing - some cultivars are mostly smooth
while others are deeply ribbed. Chose your varieties based on general
market demand and individual customer preferences.
Q - What happens to the appearance of a variety if it is cross-pollinated
with another variety grown nearby in the same field?
Nothing. Varieties grown in close proximity to one another of the same
species (Cucurbita pepo in this case) are not influenced in any
way by the pollen it receives during that growing season. However, if
seed is collected from fruit for the purposes of growing out the following
year, then there is a possibility that the plants will not be true to
type -particularly if it was a hybrid to begin with.
Varieties such as 'Big Moon', 'Atlantic Giant' and 'Big Max' belong to
a different species (Cucurbita maxima). Nonetheless, both C.pepo
and C. maxima can be planted in the same field - even for the purpose
of seed production! Different varieties within the species C. pepo
do not cross in mixed field plantings.
C. pepo and C. moschata cross readily without having any
immediate effect on the quality of fruit. The progeny produce viable seeds,
but likely result in an off-type. Therefore, isolate these 2 species for
seed production purposes.
Pumpkin and Squash Classification
The genus cucurbita (gourd family) falls into 4 major categories
(species) comprising the majority of pumpkins and squashes. It is important
to know where individual varieties belong for cross-pollination. For more
practical reasons, a pumpkin is carved, a squash is cooked, and a gourd
is to look at.
1)Cucurbita pepo can be subdivided into two groups:
- Cucurbita pepo var. pepo (true pumpkin)
This group comprises mainly the field pumpkins and acorn squash, e.g.
Acorn, Delicata, Sweet Potato, Howden, Connecticut Field, Spirit, Happy
Jack, Jack-O-Lantern
- Cucurbita pepo var. melopepo
Bush summer squash such as Zucchini, Yellow Crookneck, White Bush Scallop,
Patty Pan, Cocozelle,
2) Cucurbita maxima (true squash)
- Hubbards (all types), Giant pumpkins, Banana, Boston Marrow, Buttercup,
Delicious (all types), Turban, Marblehead
3) Cucurbita moschata
- Butternut, Winter Crookneck, Dickinson, Kentucky Field or Large Cheese
4) Cucurbita argyrosperma (formerly known as C. mixta)
- White Cushaw, Green Striped Cushaw, Tennessee Sweet Potato, Japanese
Pie
Insects and Diseases
Pumpkins and squash have few serious problems with insects and disease.
Powdery mildew is the only disease of significance while only one or two
insects, particularly the cucumber beetle, require vigilance and control.
Diseases
Powdery Mildew
Powdery mildew is present in pumpkin and squash fields almost every year
to some degree. The fungus overwinters in debris in the field or in hedgerows.
It has a fairly wide host range but wild and cultivated cucurbit hosts
seem to be the primary sources of spores.
Spores develop on debris, wild hosts, etc. and are wind blown for long
distances. The spores then land on vine crops and germinate if conditions
are right. Hot dry weather with heavy dew at night (usually in August
in Ontario) is needed to favour development of the spores. The characteristic
white powder is seen on the upper surface of leaves, leaves die down early
and collapse before the fruit have reached maximum size or maturity.
Control must be preventative. This means that fungicides will primarily
protect only uninfected leaves and stems. There are different races of
the mildew fungus. Depending on the race, fungicide treatment is more
or less effective. Once begun, repeat fungicide applications every 7-10
days until vines start to die down.
Anthracnose
This fungal disease of pumpkins can be devastating on watermelon, and
a serious problem on muskmelon and cucumber. But, on pumpkins and squash,
it occurs rarely. Symptoms are most noticeable on the fruit. The fruit
does not need to be wounded or scratched for infection to take place.
Whether or not infection occurs depends almost entirely on environmental
conditions - specifically, a combination of high temperatures and frequent
rainfall. Infected fruit will become pitted on the surface. Fruit infected
by the anthracnose fungus is obviously unmarketable. The same fungicides
that are used to control powdery mildew prevent the development of anthracnose.
Sclerotinia
Another disease occurring occasionally is sclerotinia rot, sometimes
called white rot. This disease can occur at any time of the season - in
the field on various parts of the plant, on the fruit in storage or in
transit. Proper curing of pumpkins before storage allows wounds and scratches
to scar (heal) and prevents invasion by storage disease organisms such
as the white rot fungus.
On the fruit, this disease causes a soft, watery rot, and a white cottony
growth covers the site of infection. Black pellet-like overwintering bodies
- known as sclerotia appear as the disease progress. (Figure 5).
Figure 5. Slerotinia on pumpkin fruit.
Note black pellet-like over-wintering bodies.
There are 2 critical conditions that determine whether white rot will
develop:
- wounding is necessary for the initial development of the disease.
Once disease has developed initially, it can spread to other plants
or other parts of the same plant by contact
- free moisture must be present for at least 3 days.
Sclerotinia is a weak pathogen and if these 2 conditions are not
met, disease will not develop. This fungus is always present in the soil.
Crop rotation has no affect on its abundance. However, it has been found
to be especially common in the soil around dandelion roots.
Fusarium
This disease results from infested soil. Soil can become infested by
planting infected seed. The fungus Fusarium affects plants in 2
ways: either root rot develops and the plant wilts or the fruit becomes
infected, resulting in dry rot or breakdown.
There appears to be actually 2 forms of the fungus that cause these 2
different symptoms. In the field, there may be a roughly circular area
where breakdown of the fruit occurs. There is no way to treat for this
disease. Prevention is the only means of control.
This fungus can be seed-borne. Pay special attention to using disease-free
seed. Hot water seed treatment, which kills the fungus, unfortunately
also destroys about 1/3 of the seeds as well. If outbreaks of Fusarium
have occurred, do not plant pumpkins in that field for 3-4 years.
Downy Mildew
This disease is less prevalent than powdery mildew but sometimes can
be a problem. Downy mildew grows on the underside of leaves but yellow
spots can be seen from the top. Fuzzy growth that is grey to purple is
seen on the underside of leaves. The disease affects only leaves and will
not transfer to fruit. The biggest problem is that the leaves die prematurely
from the fungus. Airborne spores travel both short and long distances,
infecting only cucurbits. The disease is controlled with fungicides as
with powdery mildew.
Fruit Rots
Anthracnose, black rot (Figure 6), phytopthora (Figure
7), soft rot or fusarium rot organisms are often related to wet
conditions as fruit ripen - particularly where fruit have contact with
the soil. Secondary fruit rots can occur due to wounding of the fruit
by cucumber beetles, rodents and otherwise rough handling. Control of
fruit rot diseases include: harvesting only fully ripened fruit, practice
good crop rotation as many of the rots are soil and debris related, good
drainage and water management, and control of cucumber beetles.
Figure 6.
Black rot (Didymella sp) cause serious problems on fruit.
Figure 7. Phytopthora
blight can cause the entire fruit to collapse.
Septoria Leafspot
This disease can show up on both the leaves and fruit of pumpkins and
winter squash. With the fruit, small raised whitish spots appear, giving
a rash-like appearance. Ordinarily, this disease does not cause fruit
to rot. This disease is very similar to oedema,
which also results in a raised whitish corky spot of similar size. However,
oedema is related to weather patterns.
Virus Diseases
A number of mosaic viruses infect squash and pumpkins, and it is often
hard to differentiate one virus from another visually. Cucumber mosaic,
squash mosaic, watermelon mosaic and zucchini mosaic viruses are the most
common. Symptoms include mottled, crinkled leaves, warty fruit with yellow
or green raised areas and malformed fruit. These viruses are transported
mainly by infected seed or insect vectors such as aphids or cucumber beetles,
and therefore control measures include controlling insect vectors. Virus-infected
plants should be rogued and removed from the field and destroyed. Otherwise,
there are no control measures for these crops once infected.
Oedema
Oedema is a physiological disorder of cucurbits and
is most frequently found with pumpkins and winter squash that are subjected
to undo moisture stress. This is most often associated with uneven availability
of moisture when immature fruit are enlarging. On pumpkin rinds the severity
may be enough to make the fruit unmarketable. (Figure 8)
The fruit surface is often raised with circular-shaped lesions that are
corky or 'crusty' in appearance and may appear irregularly over the entire
surface, or be limited to, for example, the shoulder side exposed to direct
sunlight. The crusty appearance is similar to the appearance of scab on
hard-shelled fruit, except that the oedema lesions never appear crater-like
or shrunken.
Figure 8. Oedema on pumpkin fruit appears as small
(corky) raised whitish spots.
Excessive loss of foliage due to severe powdery mildew can cause plant
stress, and oedema-like linear cracks can also develop on the surface.
On buttercup squash the corky lesions may be circular, spindle or apostrophe-shaped.
On butternut squash, oedema appears as linear growth cracks usually
on the neck portion of the fruit.
Insects
Striped Cucumber Beetle
The most serious insect pest of pumpkins is the striped cucumber beetle.
This insect is destructive in all of its life stages and to all parts
of the pumpkin and squash (Figure 9). As extensive and damaging as feeding
is by these insects, the aspect which makes them such a devastating pest
is their ability to spread bacterial wilt (Figure 10).
Figure
9. Striped cucumber beetles feeding
can devastate mature pumpkin fruit.
Figure
10. Bacterial wilt will begin with
day-time wilting which can eventually kill the plant.
Unmated adult beetles spend the winter in the shelter of fencerows, debris
and leaf litter in surrounding wooded areas. These adults emerge from
cover early in the spring and can be found on dandelions, wild cucumber
and wild plum before vine crops are planted. If they have fed on plants
in the fall that were infected with bacterial wilt, the bacteria will
pass the winter in the intestines of the beetle, ready to enter vine crops
when the beetle begins feeding on them in the spring. There is no control
for bacterial wilt. The only way to control this wilt is by controlling
the beetle.
These beetles are strongly attracted by the scent of vine crops and will
move to fields of cucumber, melons and pumpkins as soon as plantings begin
to emerge. Research projects are investigating the possibility of using
specially designed scents to attract the beetles in the spring and lure
them away from crops. Cucumber beetles must be controlled when they are
first noticed in the spring. They will continue to migrate into cucurbit
fields over a period of a few weeks. Daily vigilance is essential during
the emergence and early life of the crop while the plant is small and
susceptible.
After appearing in the spring, the beetles mate, lay eggs near emerging
seedlings and continue to feed on young plants while the eggs hatch and
larvae damage underground plant parts. As the season progresses, new adults
emerge from the soil midsummer and feed on developing vines. If they feed
on plants that are infected with bacterial wilt, the bacteria are taken
up into the insect's intestines and transferred to other plants during
feeding or when the insect leaves droppings.
Cucumber beetles can also cause feeding damage on blossoms, and late-season
feeding can occur on mature and maturing fruit.
Cucumber beetles prefer cucumber, muskmelon, winter squash and pumpkin
in descending order. However, this is not to say that pumpkins are safe
if they are next to a cucumber field.
Squash Bug
This greyish-black bug is commonly found on all vine crops but shows
a marked preference for pumpkins and squash. (Figure 11) It is slow to
emerge in the spring and usually appears about the time the vines begin
to run. The adults are shy insects and are usually found sheltered under
leaves, clods of dirt or debris. Shortly after the adults are found, there
may be small yellowish-brown to brick-red eggs laid on the underside of
the leaves.
Damage from this insect results from a toxin that is injected into the
plant when the insect feeds. This toxin can cause complete wilting of
young plants. In older plants, feeding produces dried, blackened areas
where the insect has been sucking. Severe infestations can be treated
with insecticides as described in OMAFRA Publication 363. For localized
infestations, which are more common, removing the egg masses can be effective.
Figure 11. The squash bug has a preference for pumpkins.
Damage is generally confined to the foliage, and can cause wilting of
plants in severe cases.
Sanitation is a good preventive strategy. Disk under plant refuse as
soon as possible after the crop is harvested and remove any objects, for
example - field containers, wagons, or machinery - that will provide the
shelter these insects need in order to survive the winter.
Western Corn Rootworm
This insect is really only a threat when fertilization of the flowers
is taking place. The Western corn rootworm eats the pollen in the male
flowers, interfering with fertilization. This insect really prefers corn,
and remains in the corn silks until they dry up. It prefers cucumbers
or squashes over pumpkins. If sweet corn, cucumbers or squash is grown
in addition to pumpkins, make sure that these plantings are downwind of
the pumpkins. Once the fruit has set, infestations of Western corn rootworm
in later flowers will not affect yield.
Squash Vine Borer
The squash vine borer is a pest on pumpkins, squash, marrow and gourds.
The adult is an attractive clear-winged moth with black and orange body
and orange legs fringed with long, black hairs. The larva is the destructive
stage of this pest as it feeds within the vine and causes the plant to
wilt and/or collapse often causing death. Although squash is the preferred
host, butternut squash is apparently immune to this pest.
Harvesting
Summer squashes, such as zucchini and patty-pan, are harvested when immature,
and used as a fresh vegetable either stewed, boiled or fried. They develop
very rapidly after their flowers have opened, and must be harvested before
the rind begins to harden. If the thumbnail will not easily puncture the
rind, the fruit is too old to be used for fresh-market purposes. Careful
handling is important since the young, tender fruits bruise very easily.
Pumpkins and winter squashes are not harvested until they are fully ripe
and the skins are hard. They are either pulled or cut from the vine with
a portion of the stem attached to the fruit; removal of the stem leaves
a wound through which decay organisms may enter. When gathering squashes
or pumpkins for storage, handle them carefully to avoid bruising, as damaged
fruits soon rot.
Winter squash are only harvested once the fruit are fully mature. At
this stage, the skin of the squash is hard and impervious to scratching.
Three or four months are required to mature a crop, and the fruit are
all generally ready to be picked at one time. Do not leave squash in the
field when a hard frost is predicted as this predisposes the fruit to
disease-rotting organisms - either in the field or storage.
Curing and Storing
Only the hard-shelled squashes are adapted for long-term storage, although
pumpkins, properly handled, can be kept until after Christmas. After the
fruits are harvested, they should be ripened or cured so they will keep
longer and in better condition in storage. Curing hardens the shell, heals
superficial wounds, reduces the high water-content of the fruit, and improves
the eating quality. The fruits can be cured either by leaving them in
small piles in the field for 10 days to 2 weeks when the weather is warm
and dry, or by keeping them inside at room temperature for a month. A
more reliable method is to use artificial heat at a temperature of 26°C-29°C.
(80°-85°F) with a relative humidity of about 80%.
Unlike most other vegetables, squashes and pumpkins require warm, fairly
dry storage conditions. After the curing period, carefully place the fruits
in a single layer on shelves, leaving a small space between each fruit.
Maintain a temperature of 10°C (50°F) and a relative humidity
of 70%-75%. Temperatures above 15°C (60°F) promote high respiration
and shrinkage. Do not allow the temperature to fall below 5°C (40°F).
Cold-storage rooms are not suited to the storage of pumpkins and squashes
because the high humidity encourages rot.
Ordinarily, pumpkins do not require curing as the marketing season is
relatively short for Halloween or the pie trade.
Yield Potential and Marketing
Industry Expectation
For the Jack-O'lantern trade, yields can be expected to be about 2,500
to 3,000 pumpkins per acre. This will vary somewhat with plant spacing.
Keep in mind that only 1.5-2.0 fruit adequately set per plant on average.
The smaller pie pumpkins will yield closer to 5,000 fruit/ac while the
mini's should yield 200 bushels. Each bushel holds about 125 fruit.
Most winter squash varieties yield in the range of about 20,000 kg/ha
(20,000 lbs/ac).
Yields can vary considerably depending upon what is considered to be
marketable - which in turn, is somewhat dependent upon supply and demand.
Harvest Season/Period
The pie pumpkins and some of the mini pumpkins come on early and harvest
can begin during the first part of August. However, the main Jack-O-lantern
types tend not to ripen until late August, September and into October.
Those varieties with the precocious gene will ripen considerably earlier
than those varieties without.
Winter squash varieties are usually harvested during the months of September
and October. Some of the earlier maturing varieties such as the acorn
type are mature in August. Although late harvests of winter squash may
run into November, cool wet weather, and heavy frosts may discolour fruit,
or in more severe cases cause fruit breakdown.
Main Methods of Merchandising
About half of the market for pumpkins is probably sold roadside while
the other is sold by the trailer load made up of cardboard bins. About
30-40 bins would represent 1 acre with each bin holding on average 40-45
pumpkins with a greater range of 30-60 pumpkins each depending upon size.
Bins can weigh up to 800-900 lbs.
Winter squash is sold wholesale by bushel basket or cardboard bins.
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