Photo Gallery of Vegetable Problems – Sweet Corn | Mount Vernon NWREC

		Common smut on an ear of corn caused by Ustilago maydis.
Photos of common smut of corn.
Photo Source: Karen Ward, Washington State University Plant Diagnostician	Photo Source: Lindsey du Toit, Washington State University	Photo Source:Silvia Rondon, Oregon State University

Online Resources:

Corn Smuts. Oregon State University, University of Idaho, Washington State University.

Common smut of corn (Syn. boil smut, blister smut). APSnet.

Pacific Northwest Plant Disease Management Handbook: Corn (Zea mays) – Common Smut

Common Smut (Boil Smut), UC IPM Online, University of California

Common Name: Head smut
Latin binomial: Sphacelotheca reiliana (Sorosporium reilianum = Ustilago reiliana)

Head smut gall on the ear of a corn plant. Head smut gall on the tassel of a corn plant.
Photo Source: Jerald Pataky, Professor Emeritus, University of Illinois at Urbana-Champaign

Online Resources:

Corn Smuts. Oregon State University, University of Idaho, Washington State University.

Pacific Northwest Plant Disease Management Handbook: Corn (Zea mays) – Head Smut

Common Name: High plains disease
Latin binomial: High plains virus (HPV)

Close-up view of a sweet corn leaf showing mottling from HPV.	Severe symptoms of high plains disease on sweet corn. Sweet corn plants without (top plant) and with (lower plant) symptoms of high plains disease.		Gradation in incidence and severity of damage from HPV in a sweet corn field adjacent to a wheat field. The virus is vectored by the wheat curl mite, a pest on wheat that readily moves from wheat onto sweet corn when the wheat is drying down or is harvested.
Photo Source: Carrie H. Wohleb	Photo Source: Gary Q. Pelter		Photo Source: Lindsey du Toit

Online Resources:

High Plains Disease Caused by the High Plains Virus. Pacific Northwest Vegetable Extension Group August 2003 Newsletter.

Pacific Northwest Plant Disease Management Handbook: High Plains Disease

Common Name: Southern rust
Pathogen: Puccinia polysora

Southern Rust of Corn, (Video Presentation), Plant Management Network International

Differentiating Common Rust and Southern Rust of Corn, (Video Presentation), Plant Management Network International

Insect/Mite Pests

Common Name: Bird cherry-oat aphid
Latin binomial: Rhopalosiphum padi (L.)


Live aphids, mummified/parasitized aphids, and shed aphid skins.
Photo Source: Photographer – Johnny Stark Submitted by Jenny Glass

Online Resources:

Pacific Northwest Insect Management Handbook. Chapter: Vegetables, Section: Corn, Sweet (aphids to armyworm).

Common name: Corn earworm
Latin binomial: Helicoverpa zea


Corn earworm larvae feeding in an ear of sweet corn.
Photo Source: Oregon State University HAREC-IAEP (Silvia Rondon’s lab)

Online Resources:

Corn earworm. Pacific Northwest Insect Management Handbook

Corn earworm. Integrated Peat Management, University of Illinois Extension.

Corn earworm. UC Pest Management Guidelines, Statewide Integrated Pest Management Program, University of California.

Common Name: Western corn rootworm
Latin binomial: Diabrotica virgifera virgifera

Western corn rootworm adult female. Western corn rootworm adult male.
Photo Source: Oregon State University HAREC-IAEP (Silvia Rondon’s lab)

Online Resources:

Corn rootworm (larvae). Pacific Northwest Insect Management Handbook.

Plant Management Network “Focus on Corn” Webinars:

Adult Corn Rootworm Suppression – Lance J. Meinke, University of Nebraska-Lincoln

Decision Tree for Grower Management Options: Re-Learning Corn Rootworm Management in the Transgenic Era – Ken Ostlie, University of Minnesota

Larval Corn Rootworm Management – Robert Wright, University of Nebraska-Lincoln

Resistance Evolution and IRM for Rootworm – Aaron Gassmann, Iowa State University

Rootworm Biology and Behavior – Joseph L. Spencer, University of Illinois at Urbana-Champaign

Western corn rootworm in eastern Oregon, Idaho, and eastern Washington. In the Pacific Northwest, western corn rootworm has been found in corn crops in eastern Oregon, Idaho, and eastern Washington. Though it is not as abundant in the PNW as it is in the Midwest, WCR still has the potential to damage corn in the region.
Common name (of damaging stage): Wireworm (adults are called click beetles or snapping beetles)
Latin binomial: Ctenicera spp. and Limonius spp. Several kinds of wireworms are in the Pacific Northwest. Wireworms causing the most damage in irrigated areas are the Pacific Coast wireworm (Limonius canus), the sugar beet wireworm (L. californicus), the western field wireworm (L. infuscatus), and the Columbia Basin wireworm (L. subauratus). The Pacific Coast and sugar beet wireworms are the most common. Where annual rainfall is <15 inches, the Great Basin wireworm (Ctenicera pruinina) may be a problem, especially when irrigated crops are grown on sagebrush or dry wheat land. This species usually disappears after a few years of irrigation, but may be replaced by Limonius spp. which are favored by moist conditions. West of the Cascades, other wireworm species are pests, including Agriotes spp.


Photo Source: Tim Waters, WSU Extension Educator		Photo Source: Gary Pelter, WSU Extension Educator Emeritus	Photo Source: Tim Waters, WSU Extension Educator	Photo Source:Lindsey du Toit, Washington State University

Wireworms feeding on an onion plant in a bunching onion (CFC = cepa fistulosum cross) seed crop.	Damage to a carrot root from wireworms.	A wireworm (click beetle larva). A wireworm feeding on plant roots.
Photo Source: Lindsey du Toit, Washington State University	Photo Source: Doug Young, Professor Emeritus of Washington State University	Photo Source: Oregon State University-Irrigated Agricultural Entomology Program (Silvia Rondon’s lab).

A click beetle of the species Limonius californicus, the larvae of which are wireworms. A click beetle of the species Limonius canus, the larvae of which are wireworms. A click beetle of the species Agriotes obscurus, the larvae of which are wireworms.
Photo Source: Oregon State University – Oregon State Arthropod Collection.

Online Resources:

Pacific NorthwestInsect Management Handbook: Vegetable crop pests – Wireworm.

Managing Wireworms in Vegetable Crops. Ontario Ministry of Agriculture and Food

Wireworms. VegEdge, University of Minnesota.

Wireworms & Click Beetles. Washington State University.

Wireworm Field Guide – A guide to the identification and control of wireworms, Syngenta Crop Protection Canada, Inc.

Wireworm Biology and Nonchemical Management in Potatoes in the Pacific Northwest, N. Andrews, M. Ambrosino, G. Fisher, and S.I. Rondon, Pacific Northwest Extension Publication no. PNW607