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Photo Gallery of Vegetable Problems – Cucumber


Diseases

Angular leaf spot

Curly top

Downy Mildew

Scab

White mold

Insect/Mite Pests

Western flower thrips

Abiotic Problems

Edema

(Click on photo to enlarge)

Diseases

Disease: Angular leaf spot
Pathogen: Pseudomonas syringae pv. lachrymans

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Cucumber (Cucumis sativus) – Angular Leaf Spot

Cucumber, Pumpkin, Squash: Angular leaf spot, Washington State University Hortsense


Disease: Curly top
Pathogen: Various strains of Beet curly top virus (BCTV), which are vectored by the beet leafhopper (Circulifer tenellus)
Host crops: Numerous plant species including many vegetables such as bean, beet, carrot,eggplantcoriander, pepper, potatotomato, various cucurbits such as squash, cucumber,pumpkinwatermelon, etc.

Photo Source: Ken Eastwell,
Washington State
University virologist
Photo Source: Phil Ham, OSU plant pathologist

 

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Cucumber (Cucumis sativus) – Curly Top


Disease: Downy Mildew
Pathogen: Pseudoperonospora cubensis

Dark gray sporulation of the downy mildew pathogen in angular lesions viewed from the lower surface of a cucumber leaf.
Photo Source: Lindsey du Toit, Washington State University
Microscopic photo of sporangiophores and sporangia of the cucumber downy mildew pathogen, Pseudoperonospora cubensis.
Photo Source: Jenny Glass

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Cucumber (Cucumis sativus) – Downy Mildew

Cucurbit Downy Mildew News, Michigan State University.

Downy Mildew Control in Cucurbits, National Sustainable Agriculture Information Service

Downy mildew symptoms on cucurbit plants. Michigan State University.


Disease: Scab
Pathogen: Cladosporium cucumerinum

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Cucumber (Cucumis sativus) – Scab {Gummosis}


Insect/Mite Pests

Common name (of damaging stage): Western flower thrips
Latin binomial: Frankliniella occidentalis.
Host cropsBasilBroccoliCabbageCauliflower, Cucumber, OnionPotatoPumpkinSquash,Tomato and Watermelon.

Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Western Flower Thrips Thysanoptera: Thripidae Frankiniella occidentalis

Pacific Northwest Insect Management Handbook. Chapter: Vegetables, Section: Cucumber (garden symphylan to wireworm).

Pacific Northwest Insect Management Handbook. Chapter: Irish Potatoes, Section: Lygus bug to Thrips.

Pacific Northwest Insect Management Handbook. Chapter: Vegetables, Section: Broccoli, Cabbage Other Crucifers.

Vegetables: Bean: Thrips. Washington State University Hortsense.

Vegetables: Broccoli, Cole crops: Thrips. Washington State University Hortsense.

See Diseases, pests, and other problems common to many vegetables: Western flower thrips.


Abiotic Problems

ProblemEdema
A physiological problem: prominent when air is cooler than the soil, soil moisture is high, and relative humidity is high. The low plant transpiration rates combined with an increase in water absorption by roots from the soil leads to increased cell turgor pressure, resulting in eruption of epidermal cells as the inner cells enlarge. Protrusion of the inner cells causes epidermal cells to die and discolor, resulting in a ’warty’ appearance that can be misidentified as a disease. In addition to foliar symptoms on some hosts, many cucurbit crops develop wart-like protruberances on the fruit.

Close-up view of severe edema symptoms on a pumpkin.
Close-up view of severe edema symptoms on a pumpkin.
Photo Source: Lindsey du Toit,
Washington State University.
Photo Source: 
Phil Hamm, Oregon State University.
Photo Source: Lindsey du Toit, Washington State University.

 

On-Line Resources:

http://www.omafra.gov.on.ca/english/crops/facts/00-031/#oedema

http://www.ces.ncsu.edu/depts/pp/notes/oldnotes/gp3.htm