The effect of postharvest treatments on produce losses during long-term storage of acorn squash

Acorn squash (Cucurbita pepo) is an important vegetable in the United States and Canada and is known for its nutritional content and long storage life. A breeding program in Israel for acorn squash produced several cultivars that are now commercially available. The fruits of the Israeli cultivars have high sugar content (12-18% total soluble solids) and a black-green rind with a yellow-orange flesh. Current agricultural practices in Israel call for growing acorn squash plants prostrate, in an open field. However, experimental trellised growth of acorn squash in greenhouses covered with 50 mesh nets enables a long growing season during the winter, by providing protection against viruses transmitted by insects. Trellising vs. prostrate growth efficiently uses the limited protected space and promotes high plant productivity. In addition, fruit quality is improved in trellised squash. Trellised squash fruits are uniformly colored rather than having an orange section where they touch the ground and are less prone to insect damage. Nevertheless, the long growth period during the wet season promotes a high incidence of fungal rots that develop on decaying plant parts. An initial inoculum of molds from the field represents a major complication for long-term storage of the harvested squash, resulting in a significant produce loss. In this study, the application of precise steam treatments was evaluated for improving the storability of trellised acorn squash fruits produced in netted greenhouses during two consecutive seasons. Our results indicate that the steam postharvest treatment can reduce fruit decay incidence with a minimal effect on fruit quality.