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Pumpkin and Winter Squash Harvest, Curing and Storage Tips

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10/16/2018 5:00 PM

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10/16/2018 7:00 PM

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From:   DeWitt, Shannon
Sent:   Monday, September 17, 2018 2:34 PM
Subject:        FW: Pumpkin and Winter Squash Harvest, Curing and Storage Tips
Attachments:    Twilight Tour Flier_October.pdf
 
 
From: Wszelaki, Annette Lynn
Sent: Friday, August 31, 2018 9:37 AM
Subject: Pumpkin and Winter Squash Harvest, Curing and Storage Tips
 
Good morning, 
 
With the season we’ve had, many are seeing their pumpkins maturing earlier than usual in the field. The article below, from the UMass Extension Vegetable Notes, gives excellent tips on when to harvest and how to make those pumpkins and winter squash last after harvest! 
 
Also, a reminder, we will have the TFVA Twilight Tour showcasing our pumpkin variety trial on October 16th at Green Acres Farm in Milan. Please see the attached flyer for more info.
 
Have a great Labor Day weekend!
Annette
 
 
PUMPKIN AND WINTER SQUASH HARVEST, CURING AND STORAGE
It might feel a little early to be thinking about winter squash, but we’re seeing fruit at various stages of ripeness out there
and, in a year marked by frequent rains, folks might be starting to make plans for getting crops out of the field. Winter
squash and pumpkin fruits that remain in the field face a daunting list of diseases, insects, and weather events that could
threaten fruit quality. Once the fruit reaches maturity, prompt harvest and careful postharvest handling is generally preferable
to leaving fruit in the field, particularly in a relatively wet season, such as this one. This is especially true if you know
that your pumpkins or squash are in fields that were previously infected with Phytophthora blight, which can explode after
a heavy rain. 
 


Pumpkin Harvest Timing: Since the pumpkin market lasts from Labor Day to Halloween, pumpkins may need to be held for several weeks before
they can be sold. Onefactor in deciding whento harvest is the condition of the vines. Intact foliage protects fruit from the sun, and when vines
and foliage go down from powdery or downy mildew, fruit can get sunscald. Foliar diseases, especially powdery mildew, can also reduce quality
of pumpkin handles, leading to reduced marketability for jack-o-lantern pumpkins. As we move into September, the other major factor in deciding
when to harvest is avoiding chilling injury. Chilling hours accumulate when squash or pumpkins are exposed to temperatures below 50°F in the
field or in storage. Injury increases as temperature decreases and/or length of chilling time increases. This is particularly important for squash headed
into long term storage.
 
There can be extra work involved in bringing fruit in early and finding good storage locations, especially for growers who normally have pick-your-
own harvest. However, we recommend that growers harvest as soon as crops are mature and store under proper conditions, if it is feasible. Proper curing and storage conditions are key for pumpkins in particular, because improperconditions can result in handles shrinking and shriveling, making the pumpkins unmarketable. If you need to hold fruit in
the field for pick-your-own or any other reason, using a protectant fungicide (e.g. sulfur, oil, or chlorothalonil) along with one of the targeted powdery mildew products can help protect from black rot, powdery mildew, and other fungal fruit rots . Scout for insects feeding on the fruit and handles, which may include squash bug nymphs or adults and striped cucumber beetle, and control them if damage is evident. See the Southeastern U.S. Vegetable Crop Handbook for treatment recommendations.
 
Harvest: Despite their tough appearance, squash and pumpkin fruit are easily damaged. It is important to avoid bruising
or cutting the skin during harvest. Once the rind is bruised or punctured, decay organisms will invade the fruit and quickly
break it down. Place fruit gently in containers and move bins on pallets. Use gloves to protect both the fruit and the workers.
For some squash, especially butternut, stems can be removed to prevent them from puncturing adjacent fruit during
harvest and storage. If stems are removed, allow the stem scars to heal before putting into storage (see Curing Conditions
below).
 
Harvest Timing for Eating Quality: For pie pumpkins and winter squashes, harvest timing determines the flavor and
texture of the fruit. Before understanding when the best time is to harvest squash, it’s important to understand the difference
between “mature” squash and squash that is ready to be eaten. As squash fruits grow, they accumulate starch, which
is then converted into sugar both during maturation in the field and after harvest during storage. The balance of starch
(texture) and sugar (sweetness) in a squash determines the eating quality. Squash is “mature” when seeds are completely
filled. If squash is harvested before it is mature, the fruit will use starch reserves from the flesh to fill the seeds, resulting
in poor flesh quality. Immature squash will also not have enough starch to convert into sugar later on. For some squash
types (e.g. acorn and delicata), the mature fruit can be eaten immediately after harvest. Other squash types (e.g. butternut,
hubbard, kabocha), need more time to convert starches to sugars and must be stored for specific amounts of time before
they are eaten.
 
Most squash varieties are mature and ready to be harvested 50-55 days after fruit set, or days after pollination (DAP). In
many varieties, this is many weeks after the fruit turns a marketable color, which can be misleading. According to Dr.
Brent Loy, researcher emeritus at the NH Agricultural Experiment Station, days to maturity listed in seed catalogs are often
in error, especially for acorn squash; catalogs often state 70-76 days to maturity (from time of seeding) when in reality
it’s more like 90-100 days to maturity (Keep in mind, this article was written for MA growers… our conditions in the South tend to speed up maturity!).  It’s not necessarily easy to keep track of fruit set, so there are some other indicators— see the end of this article for more information about specific varieties.
 
Curing Conditions: In some cases, squash needs to be stored for a short period of time (5-10 days) at a high temperature
(80-85°F) and 80-85% relative humidity immediately after harvest, either in the field if weather allows, or in a well-venti-
lated barn, greenhouse, or high tunnel. Night temperatures should not drop below 60°F. These conditions will speed up the
conversion of starches to sugars to achieve good eating quality earlier on and will allow fruit skin to harden and wounds
to heal. You may not want to cure squash if it’s destined for long-term storage and if it is free of wounds—squash in longterm
storage should have sufficient time to convert starches to sugars and can go directly into storage conditions without
the extra boost. Squash types like acorn and delicata are ready to eat at harvest (if they’re harvested when they’re mature!)
and only need to be cured if you want to store them and the skin is wounded.
 
Storage: Pumpkins and winter squash should be stored in a cool, dry, well-ventilated storage area. Store fruit at 50-60°F
with 50-70% relative humidity. Chilling injury is possible at temperatures below 50°F, and long-term storage at temperatures
above 60°F will result in weight loss due to increased respiration rates. Large fluctuations in temperature favor
condensation on fruit within the bin, which encourages disease. Therefore, fruit temperature should be kept as close to
the temperature of the air as possible to avoid condensation and fruit rot. Relative humidity above 70% provides a favorable
environment for fungal and bacterial decay organisms, and relative humidity below 50% can cause dehydration and
weight loss. In a greenhouse, temperature can be managed with ventilation on sunny days; heaters will be needed for storage
into November and beyond. An inner curtain can reduce heat loss and cost.
 
Storage life depends on the condition of the crop when it comes in and your ability to provide careful handling and a
proper storage environment. All fruit placed in storage should be free of disease, decay, insects, and unhealed wounds.
See the end of this article for maximum storage times for different types of squash. Fruit that has been exposed to chilling
temperatures (below 50°F) will not store well and should be marketed first.
 
Few farms have the infrastructure to provide ideal postharvest conditions for all of their fall crops. Fortunately, finding a
method that is ‘good enough’ often does the job. Even if it is difficult to provide the ideal conditions, storage in a shady,
dry location, with fruit off the ground or the floor, is preferable to leaving fruit out in the field.
 
Cucurbita pepo (acorn, delicata, sweet dumpling, some pie pumpkins): Acorn squash turns dark green 2-3 weeks
after fruit set, which is 40-50 days before it should be harvested. Because acorn squash can be marketed as soon as
it turns dark green, regardless of eating quality, many acorn varieties will never accumulate enough starch and will
therefore never be sweet. UNH has developed two varieties, ‘Honey Bear’ and ‘Sugar Dumpling’, that both have high
sugar content at harvest. Harvest C. pepo squashes when the ‘ground spot’ (the part of the squash that lays on the
ground) is dark orange. Pie pumpkins should be harvested when the skin is fully orange. These varieties can be eaten
at harvest and will store for 2-3 months.
 
Cucurbita maxima (kabocha, hubbard, buttercup): Stems becomes dry and corky when the fruit is ready to be
harvested. These are more susceptible than other squash to sunburn and so if vines go down from disease, they should
be harvested early (40 DAP), cured, then stored at 70-75F for 10-20 days to achieve acceptable eating quality. These
have high starch content at harvest and so need to be stored for 1-2 months before being eaten, with the exception of
all mini-kabochas and all red-skinned kabochas, which can be eaten at harvest. They will store for 4-6 months.
 
Cucurbita moschata (butternut, some edible pumpkins): Butternut will turn tan 45 DAP but should not be harvested
for another 2 weeks. Mini-butternut can be eaten at harvest and will store for 3 months. All others should be stored
1-2 months before eating to allow for starches to be converted into sugars and will store for 4-6 months. Carotenoid,
the pigment that gives squash its yellow/orange color, also increases in storage for these squash, giving them more
color and making the more nutritious.
 
--Written by G. Higgins and R. Hazzard, compiled 2018 from Eating Quality in Winter Squash and Edible Pumpkins and
The Nuts and Bolts of Fruit Quality in Cucurbits by Brent Loy researcher emeritus, New Hampshire Agricultural Experiment
Station and professor emeritus of genetics, UNH.
 
 
Annette Wszelaki
Professor, Commercial Vegetable Extension Specialist
Department of Plant Sciences
252 Ellington Plant Sciences Building, 2431 Joe Johnson Drive
Knoxville, Tennessee 37996
 
865.974.8332 Office / 865.974.1947 Fax
 


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Created at 9/18/2018 11:06 AM by Mike, Ashley Marie
Last modified at 9/18/2018 11:06 AM by Mike, Ashley Marie