Home Garden Disease Controls
The Pennsylvania State University
Cooperative Extension
Sweet Corn
How important are diseases on sweet corn?
A few diseases can affect sweet corn. Occasionally, a particular disease may become significant. But usually, diseases are of minor significance when control suggestions listed at the end of this publication are followed.
What diseases can affect sweet corn?
Listed below are four diseases that most frequently occur on sweet corn. Symptoms are described briefly. Colored pictures of disease symptoms can be seen in the publication Identifying Diseases of Vegetables.
Stewart's Bacterial Wilt
Yellow to brown streaks, occasionally up to 1-inch wide, develop on leaves and may extend the length of the leaf. Brown discoloration and sometimes rotted cavities form in the center of the stem near the soil line. Plants affected early may die; plants affected late may be stunted or merely have streaked leaves. The disease is most prevalent following mild winters, especially in the southern and south-eastern parts of Pennsylvania.
Smut
Smut is characterized by presence of large fleshy, irregular galls on leaves, stems, ears, and tassels. Immature galls are white and spongy; mature galls turn brown and contain powdery dark spores. Smut is promoted by plant injury caused by cultivation, insects, and hail.
Rust and Leaf Spots
Rust is characterized by reddish to brown rusty powdery areas on the top surfaces of leaves. Leaf spots can be small or large; the spots usually are elongated and appear first on oldest leaves. These diseases can be significant, but usually only late in the season.
Disease Control Program
(1) Grow varieties with resistance to Stewart's wilt when needed.
(2) Remove and dispose of smut balls before they turn black and break open. Dispose of stalks and leaves as soon as harvest is over.
Note: Where trade names are used, no discrimination is intended
and no endorsement by the Cooperative Extension Service is implied.
Information provided is intended for consideration by the user, but is not
intended to be a recommendation. Production decisions should be based on
consideration of many types of information (scientific, experiential, economic,
legal, etc.) available to the user.
