Harvesting and Storing of Pumpkins, Winter Squash and Gourds
Fall is the season for pumpkins, winter squash and gourds and Maurice Ogutu, a University of Illinois Extension horticulture educator based in Chicago, recommends consumers follow these guidelines.
Halloween pumpkins are harvested in September through October. Sometimes harvesting may start in mid August to early September which requires good handling and storage of the pumpkin fruit before selling to the customers in late October.
The first frost occurs in early to mid October in northern parts of the state when the pumpkin fruits are still curing outside in the fields. The growers in pick-your-own pumpkin operations use this method to ensure that pumpkins are well cured in the field before picked up by their customers. Some growers practicing conventional pumpkin marketing systems where the fruit is picked, washed, dried and sold to customers on weight or per fruit basis also use this method.
It is important to note that pumpkin fruits can tolerate light frost that kill the vines only but more fruit loss can occur if the frost caused injury on the fruit surface as the damaged areas act as avenues for fungal and bacterial fruit rot pathogens. Remove pumpkins from the fields before the hard freeze (when the night temperatures are less than 27 degrees (F) or else you may risk losing 80-90 percent of the fruits.
The pumpkin fruit is harvested when it is uniformly orange and the rind is
The pumpkin fruit is harvested when it is uniformly orange and the rind is hard. Green immature fruits may ripen during the curing process but not after the vines are killed by frost. The vines need to be dry when fruits are mature. Handle the fruit with care to avoid cuts and bruises. Harvest the fruit by cutting it off the vine with a sharp knife or a pair of looping shears leaving 3-6 inches of the stem attached to the fruit. This makes the fruit look more attractive and less likely to be attacked by fruit rot pathogens at the point of stem attachment. Do not carry the pumpkin fruit using the fruit stems because the fruit is very heavy and may lead to detachment of the fruit stem. Wash the fruit with soapy water containing one part of chlorine bleach to ten parts of water to remove the soil and kill the pathogens on the surface of the fruit. Make sure the fruits are well dried before setting in a shed to cure.
Pumpkin fruits are cured at 80-85°F and 80-85 percent relative humidity for 10 days. This is done to prolong the post harvest life of the pumpkin fruit because during this process the fruit skin hardens, wounds heal and immature fruit ripens. After curing, the fruits can be sold to the customers and the remaining fruits stored.
Store the fruits in a cool dry place. Put the fruits on a single layer on wooden pallets with enough space in between the fruits (the fruits should not touch each other) and do not place them on a concrete floor. Improve the air circulation within the storage area by letting in cool air at night and use a fan to circulate air during daytime. Do not let in warm air from outside into the storage during the daytime. The optimal storage condition is 50-55°F temperature and relative humidity of 50-70 percent. The relative humidity is very important within the 50-70 percent range because high humidity leads to settling of moisture on fruit surfaces, which increases decay of the fruit and low relative humidity may cause dehydration of the fruit. Under these conditions you can keep the fruits for about 2-3 months.
Store the fruits away from apples since apples produce ethylene gas as they ripen which speeds up the ripening process in pumpkins, hence decreased shelf life. Check the fruits regularly and remove the ones that are rotten because if not removed, they will spread the pathogens in the storage area.
Winter squash such as Butternut, Acorn, Hubbard, and other types are mature when the skin (rind) are hard and cannot be punctured by thumbnails. The mature fruit has a dull and dry skin compared to shiny, smooth skin of immature fruits. Remove stem completely from Hubbard types and if desired leave only 1-inch long stump on the fruit. Stems longer than 1-inch tend to puncture adjacent fruits when in transit or storage. Butternut, Hubbard and other squash types do not need be cured as the benefits are less compared to pumpkins, while curing is very detrimental in Acorn types as it leads to decline in quality. Acorn types have the shortest storage time of 5-8 weeks at 50°F and relative humidity of 50-75 percent.
Butternut, Turban, and Buttercup types can be stored at the same temperature and relative humidity as Acorn types but have a longer storage time of 2-3 months. The Hubbard types can be stored much longer than the rest (5-6 months) at 50-55°F and relative humidity of 70-75 percent. Winter squash should be marketed or used immediately when taken out of storage to avoid development of fruit rot diseases.
Gourds are of different flower colors (yellow, white), shapes and sizes. They should be harvested before frost when fruit is mature. As gourds mature, stems turn brown and become dry. Don’t use “thumbnail” test on gourds as it can cause a dent on the shell of the unripe gourd and lower its quality.
Harvest the fruit by using a sharp knife or shears to cut the stem from the vine and leaving a few inches of the stem attached to the fruit. Do not handle the gourd by its stem since the stem can easily detach from the fruit and lower its decorative value.
If the fruit is dirty, wash in soapy water to remove soil and rinse in clean water with household bleach. One part to 10 parts water kills soil-borne pathogens. Then dry each fruit with a soft cloth. Spread the fruits so that they do not touch each other in shelves lined with newspapers in a well-aerated shed. Turn the gourds daily and change damp newspapers for 1 week. The outer skin will harden this time and surface color develops. The gourds need to be wiped with a damp cloth soaked in household disinfectant and placed in a warm, dry dark area for 3-4 weeks for further curing. The decorative gourd can stay in its natural state for 3-4 months and as long as six months with a protective coat of paint or wax on the surface.