HomePest managementKeys for Identifying Vegetable DiseasesCucurbit Diagnostic KeyWinter Squash Disease KeyWinter Squash Fruit Symptoms

Winter Squash Fruit Symptoms

Originally prepared for Vegetable MD Online by Thomas A. Zitter.

This page includes symptoms caused by:

Bacteria

Angular leaf spot | See factsheet for more information (LIHREC)

diseased winter squash fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Brown spots, 1-4 mm in diameter, circular, water-soaked often with raised white center. Leaf symptoms also present.

Bacterial leaf spot | See factsheet for more information (LIHREC)

diseased butternut squash fruit
Photo courtesy of Meg McGrath, Cornell University, LIHREC, NY.

Symptoms: Brown spots varying greatly in size (up to a half dollar). Can develop into a water soaked rot that leads to fruit collapse. Leaf symptoms also present.

Fungi & Oomycetes

Anthracnose | See factsheet for more information (LIHREC)

diseased delicata squash fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Dark brown spots, circular, 2-5 mm, or larger in diameter, sunken with salmon-colored fungal growth under moist conditions or tiny black specks. Spots often develop in storage. Leaf and stem symptoms also present.

Choanephora

Symptoms: Symptoms usually start to develop at the blossom end of fruit touching the ground. Affected tissue develops a wet, soft rot. The pathogen’s growth is distinctive. It looks furry (hairy) and like a lot of pins in a pin cushion. Blossoms and leaves can also be affected.

Fusarium dry rot | See factsheet for more information (LIHREC)

diseased butternut squash fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Tan, circular spots. Firm dry rot. White fungal growth found on the surface side touching moist soil. Uncommon.

Gummy stem blight | See factsheet for more information (LIHREC)

diseased butternut squash fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Black spots, circular or irregular, can be large. Initially water-soaked, pinkish then turning black. Fruit often collapse due to other rotting organisms. Symptoms and signs (pycnidia) often develop in storage. The foliar phase is called gummy stem blight black rot.

Phytophthora fruit rot | See factsheet for more information

rotting winter squash fruits
Photo courtesy of Chris Smart, Cornell University, NY.

Symptoms: Water-soaked or sunken spots. Enlarge to encompass entire fruit with white yeast-like fungal growth. Leaf and stem symptoms also present. Localized occurrence.

Plectosporium blight | See factsheet for more information (LIHREC)

Symptoms: Light tan spots, small spindle-shaped, sunken, dry, scabby. Spots primarily on fruit handles, stems, and sometimes on leaves.

Pythium

Symptoms: White spots, circular, 1-2 mm in diameter, raised like a rash. Leaf symptoms also present.

Scab

diseased winter squash fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Beige or brown spots, dry and corky, small, circular. Initially sunken but can become raised. Leaf and stem symptoms also present.

Sclerotinia white mold

diseased winter squash fruit
Photo courtesy of Meg McGrath, Cornell University, LIHREC, NY.

Symptoms: Watery, odorless rot. The pathogen produces a white cottony mold with black, hard, pea-like bodies. Develops in field or in storage. Localized occurrence, especially where beans or cabbage were grown.

Septoria

diseased acorn squash
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: White spots, circular, 1-2 mm in diameter, raised like a rash. Leaf symptoms also present.

Phytoplasmas

Aster yellows

diseased butternut squash plant and fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Fruit smaller and lighter in color than normal. Leaf symptoms also present.

Viruses

Cucumber mosaic virus | See factsheet for more information (LIHREC)

Symptoms: Fruit mottled, discolored (e.g. green blotches), distorted, bumpy, malformed. Plant stunted. Leaf symptoms also present.

Watermelon mosaic virus | See factsheet for more information (LIHREC)

Symptoms: Fruit mottled, discolored (e.g. green blotches), distorted, bumpy, malformed. Plant stunted. Leaf symptoms also present.

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