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Cucumber 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)

three cucumber fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Brown circular lesions 1-4 mm in diameter that appear water soaked and often produce a raised white center.

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

Symptoms: Brown lesions with variable sizes that can be as large as a half dollar. These can develop into a water soaked rot that leads to fruit collapse.

Fungi & Oomycetes

Anthracnose | See factsheet for more information (LIHREC)

two cucumber fruit
Photo courtesy of W. R. Sitterly, Brevard, NC.

Symptoms: Dark brown circular lesions 2-5 mm in diameter that are typically sunken with either black specks or salmon-colored fungal growth under moist conditions. These spots often develop in storage.

Choanephora fruit rot

Symptoms: Begins as a wet rot on the blossoms and blossom end of fruit. Develops into a soft and watery rot covered with distinctive fungal growth characterized by whitish-gray fungal strands and pincushion-like black spores.

Fusarium dry rot

Symptoms: Tan, circular lesions with a firm, dry rot. White fungal growth also present. Typically found on the surface of the fruit that is touching moist soil.

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

cucumber fruit with lesions
Photo courtesy of W. R. Sitterly, Brevard, NC.

Symptoms: Black lesions that are circular or irregular and can become large. These are initially water-soaked and turn pinkish before developing into the black lesions in the picture above. Fruit will often collapse due to other rotting, opportunistic organisms. Symptoms and pycnidia often develop in storage.

Phytophthora fruit rot | See factsheet for more information

three rotting cucumber fruit
Photo courtesy of Meg McGrath, Cornell University, LIHREC, NY.

Symptoms: Water-soaked or sunken lesions that can enlarge to encompass the entire fruit. These are covered in white yeast-like fungal growth.

Plectosporium blight | See factsheet for more information (LIHREC)

Symptoms: Light tan lesions that are small, spindly-shaped, sunken, dry, and scabby. The lesions primarily develop on fruit stems.

Pythium rot

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

Symptoms: White circular lesions 1-2 mm in diameter that are raised and can enlarge to encompass the whole fruit.

Scab

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

Symptoms: Beige or brown circular lesions that are dry, corky, and small. These are initially sunken and can occasionally be raised.

Sclerotinia white mold

Symptoms: Watery and odorless rot characterized by a white, cottony mold and black, hard, and pea-like bodies. This can develop in the field or in storage. Occurrence is often localized, especially where beans or cabbage were grown.

Septoria

Symptoms: White lesions that are circular, 1-2 mm in diameter, and raised like a rash.

Phytoplasma

Aster yellows

Symptoms: Fruit are smaller and lighter in color than normal.

Viruses

Papaya Ringspot Potyvirus | See factsheet for more information (LIHREC)

four diseased cucumber fruit
Photo courtesy of T.A. Zitter, Cornell University, Ithaca, NY.

Symptoms: Fruit are mottled, discolored, distorted, and bumpy. The whole plant may also be stunted.

 

More information: