Pacific Northwest Vegetable Extension Group

of Washington State University, Oregon State University, and University of Idaho

Photo Gallery of Vegetable Problems

Squash

(Click on photo to enlarge)

Diseases

Disease: Angular leaf spot
Pathogen: Pseudomonas lachrymans

Photo of Angular leaf spot on squash Photo of Angular leaf spot on squash

Photo Source: D.A. Inglis

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Squash (Cucurbita spp.) – Angular Leaf Spot

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

Disease: Curly top
Pathogen: Curly top virus
Host crops: Numerous plant species including many vegetables such as bean, beet, carrot, eggplant, coriander, pepper, potato, tomato, and various cucurbits such as squash, cucumber, pumpkin, watermelon, etc.

Photo of curly top on butternut squash Photo of curly top on winter squash Phot of curly top symptoms on acorn squash leaves Photo of symptoms of curly top on squash leaves
Squash, butternut Squash, winter Symptoms of curly top in an acorn squash crop. Symptoms of curly top in a squash crop.
Photo Source: E. J. Sorensen Photo Source: Phil Ham, OSU plant pathologist

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Squash (Cucurbita spp.) – Curly Top

Cucumber, Pumpkin, Squash: Curly top (Beet curly top virus), Washington State University Hortsense
 

Disease: Powdery mildew
Pathogen: Golovinomyces cichoracearum (formerly Erysiphe cichoracearum) and Podosphaera fuliginea (formerly Sphaerotheca fuliginea)
Host crops: All cucurbit vegetables (e.g. cucumber, cantaloupe, melon, pumpkin, and squash). There are different races of the pathogens.

Photo of Powdery mildew on squash Photo of powdery mildew on squash leaves Photo of powdery mildew on squash leaf Photo of powdery mildew on squash leaf
       
Photo Source: D.A. Inglis Photo Source: Lyndon Porter, USDA-ARS
Photo of powdery mildew on squash leaves
 
Photo Source: Lyndon Porter, USDA-ARS

On-Line Resources:

How to Manage Pests: Pests in Gardens and Landscapes: Powdery Mildew on Vegetables. UC IPM Online, University of California

Pacific Northwest Plant Disease Management Handbook: Squash (Cucurbita spp.) – Powdery Mildew

Cucumber, Pumpkin, Squash: Powdery mildew, Washington State University Hortsense

Disease: Mosaic
Pathogen: Suspected watermelon mosaic virus

Photo of suspected watermelon mosaic virus on summer squash
Photo Source: E. J. Sorensen

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Squash (Cucurbita spp.) – Virus Diseases

Common name: White mold
Latin binomial: Sclerotinia sclerotiorum
Host crops: Cucurbit vegetables (e.g. cucumber, pumpkin, and squash), pepper, snap bean, carrot, cabbage, cauliflower, lentil, field pea, potato, radish, and many weed species.

Photo of white mold on squash Photo of white mold on squash Photo of white mold on squash Photo of white mold on squash vines
White mold infecting of a gourd of a squash plant. White mold on squash vines.
Photo Source: Lyndon Porter, USDA-ARS
Photo of white mold on squash vines Photo of white mold on squash vines
Pathogen bleaches the vines white. Black sclerotia (dormant survival structures) of the pathogen are often produced inside infected vines.
Photo Source: Lyndon Porter, USDA-ARS

On-Line Resources:

Pacific Northwest Plant Disease Management Handbook: Pepper (Capsicum sp.) – White Mold

Fruit Rots of Squash and Pumpkins: Sclerotinia White Mold, Vegetable MD Online, Cornell University

White Mold of Vegetables, Pest Management Fact Sheet #5084, The University of Maine
 

Insect/Mite Pests

Common name: Bean aphid, green peach aphid, melon aphid, and potato aphid
Latin binomial: Aphis fabae , Myzus persicae, Aphis gossypii, and Macrosiphum euphorbiae respectively
Host crops: In addition to tomato, eggplant and pepper, bean, melon, sweet corn, corn seed, carrot, cucumber, and eggplant the bean aphid can feed on spinach, Swiss chard, squash, pumpkin, and beet. The green peach aphid can feed on potato, tomato, eggplant, pepper, broccoli, cabbage, spinach, Swiss chard, squash, pumpkin, beet and many weed species including Brassicaceae (cruciferous) weeds. The melon aphid can feed on cucumber, melon, pumpkin, squash, spinach and spinach seed. The potato aphid can feed on cucumber, potato, melon, tomato, pumpkins, squash, and corn seed.

Photo of green peach aphid nymph on leaf Photo of green peach aphid Photo of aphid damage on leaf
Green peach aphid may be found along the midrib on the underside of leaves of a host plant. Mature aphids are about 2 mm long (ca. 1/16 inch), egg-shaped, and the color of the wingless nymphs and adults ranges from pinkish yellow to yellowish green. There are usually multiple individuals in a single colony. The green peach aphid tends to overwinter in stone fruit trees. By late May to early June, individual aphids in a colony develop wings and fly to vegetable crops and a wide range of weeds. As the aphids disperse (June to August), they can transmit important viruses including potato leaf roll virus and potato virus Y. The easiest way to scout for aphid colonies is to search perimeter vegetable plants for copious amounts of sticky, glistening honeydew coating the upper surfaces of lower leaves of plants. Honeydew may contain numerous cast (shed) skins (white to gray) and a black sooty mold (fungus) that colonizes aphid honeydew.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Pacific Northwest Insect Management Handbook: Vegetable crop pests-Aphid

Pacific Northwest Insect Management Handbook: Pumpkin and squash – Aphid

Common Insect & Mite: Aphids, Washington State University Hortsense

See Diseases, pests, and other problems common to many vegetables: Green peach aphid

For aphids on other crops see: potato, and pumpkin
 

Common name: Squash bug
Latin binomial: Anasa tristis
Host crops: Cucurbit vegetables (e.g. Pumpkin and squash).

Photo of Squash bug nymphs Photo of adult adult squash bug Photo of squash bug showing long beak
Squash bug nymphs are wingless and range from 1/8 to 1/2 inch long with a grayish white body color. They often congregate in groups on the undersides of leaves. The adult squash bug has a flattened, elongate body, dark to grayish brown with a speckled pattern on the dorsum, and measure about 1/2 to 5/8 inch long. They may appear to have yellow to orange-striped borders on the abdomen. They release a foul odor when crushed. Squash bugs have a long “beak” that they insert into the vine or foliage, and feed by sucking sap from the plant. Yellow specking that later turns brown may appear on leaves where they feed. Severe feeding on young vines, or older vines during the heat of summer, can lead to plant wilingt distal to the point of feeding.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Pacific Northwest Insect Management Handbook. Chapter: Vegetables, Section: Pumpkin and Squash, pt.2.

Vegetables: Cucumber, Pumpkin, Squash: Squash bug.. Washington State University Hortsense.

See See Diseases, pests, and other problems common to many vegetables: Squash bug.
 

Common name: Western flower thrips
Latin binomial: Frankliniella occidentalis.
Host crops: Basil, Broccoli, Cabbage, Cauliflower, Cucumber, Onion, Potato, Pumpkin, Squash, Tomato and Watermelon.

Photo of adult Western flower thrips Photo of immature Western flower thips
Adult Western flower thrips are minute (less than 1/8 inch long) narrow-bodied insects that range from straw to dark yellowish-brown in color. Their four wings are very narrow and characterized by long fringed hairs. Immature Western flower thrips resemble the adults but are smaller, wingless and translucent yellow in color. There are multiple generations per year and thrips may invade vegetable fields when alternate flowering plants dry up in the summer or when an adjacent host crop is harvested.
Photo Source: Michael Bush, WSU Extension, Yakima, WA

On-Line Resources:

Western Flower Thrips Thysanoptera: Thripidae Frankiniella occidentalis,

Cucurbits: Thrips, UC IPM Online, University of California

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

Abiotic Problems

Problem: Edema
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.
 

Severe wart-like growths on a pumpkin caused by edema Close-up view of severe edema symptoms on a pumpkin Small but extensive symptoms of edema on a winter squash Close-up view of edema symptoms on the surface of a winter squash
Severe wart-like growths on a pumpkin caused by edema. Close-up view of severe edema symptoms on a pumpkin. Small but extensive symptoms of edema on a winter squash.Close-up view of edema symptoms on the surface of a winter squash.
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.htm#oedema

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

Our pages provide links to external sites for the convenience of users. WSU Extension does not manage these external sites, nor does Extension review, control, or take responsibility for the content of these sites. These external sites do not implicitly or explicitly represent official positions and policies of WSU Extension.

WSU Mount Vernon NWREC, 16650 State Route 536, Mount Vernon, WA 98273-4768, 360-848-6120
Contact Us: Lindsey du Toit and Carol Miles