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Pests & Diseases
Cucumber beetles will attack seedlings, vines, and growing gourds, while the aptly named squash bugs damage vines and attack maturing fruit.

Squash vine borers are an annual nuisance due to overwintering in the soil, particularly for winter squash, but can damage zucchini when larvae bore into vines and prevent moisture absorption. Symptoms are often mistakenly attributed to bacterial or fusarium wilt but can be confirmed by holes at the base of wilted leaves. Other pests include aphids, cutworms, leafminers, mites, mole crickets, and whiteflies.

A lack of calcium will cause blossom end rot, the formation of watery, black bloating at the ends of fruit, most commonly found in tomatoes.

Angular leaf spot is a bacterial disease that can affect zucchini, cucumbers, and honeydew melons. Phytophthora blight is a fungal disease that can decimate zucchini and other cucurbits, destroying entire fields.

Mosaic viruses and mildew (powdery and downy) can appear on foliage. Given the faint, green-grey markings on mature zucchini leaves, these splotches and streaks can be mistaken for mildew, but are normal.

Storage & Packaging
Since harvested when immature, zucchini is not ideal for lengthy storage. This summer squash will lose moisture and deteriorate quickly, but can be stored for a few days from 41 to 50°F with high humidity. Zucchini does not ripen after harvest and can be mildly sensitive to ethylene-producing fruits and vegetables.

References: North Carolina Cooperative Extension, University of Arizona Cooperative Extension, UC Davis Postharvest Technology Center, University of Florida/IFAS Extension, University of Georgia, University of Illinois Extension, USDA.


Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.

U.S. Grade Standards Days Since Shipment % of Defects Allowed Optimum Transit Temp. (°F)
10-5-1 5

There are no good arrival guidelines for this commodity specific to Canada; U.S. guidelines apply to shipments unless otherwise agreed by contract.

References: DRC, PACA, USDA.


• There are no size requirements (diameter or length) in the U.S. grade standards for summer squash
• Bruising is scored as a defect when any indentation is more than 1/8 inch in depth or exceeds an area of 1/2 inch in diameter
• Scuffng is scored as a defect when affecting more than 10% of the surface or when discolored, affecting more than 5% of the surface area
• Any amount of decay, including decay affecting the stem, is scorable against the 1% decay tolerance
• A gummy substance can exude from squash, particularly from cut or broken stems; this shall not be scored as decay unless the underlying flesh is breaking down.

Source: Tom Yawman, International Produce Training,

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This information is for your personal, noncommercial use only.