Your Sweet Corn Could be Rusting
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January 13, 2017
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Extended wet, cool weather over most areas of Mississippi has created difficulties for home gardeners. Vegetable crops are behind schedule in development, and tomatoes, peppers, Irish potatoes, and other vegetables are having more than their share of disease and other pest problems.
The most recent disease which has made its appearance in gardens is common rust, which affects most varieties of sweet corn. Rust can be identified by the small (about one-eighth to one-fourth inch in diameter), raised reddish-brown blisters which appear on either leaf surface of corn leaves. Most of the blisters, however, appear on the upper leaf surface of young to middle-aged leaves.
Corn rust can be identified with certainty by rubbing a white cloth or paper towel across the surface of the leaf. If the leaf is infected by common rust, a reddish or orange residue will remain and is easily visible when the cloth or towel is examined.
The blisters contain thousand of rust spores which are picked up by wind and blown to other corn plants, where they land and cause new spots of infection. The corn rust fungus spreads rapidly across a planting of sweet corn, especially under wet, cool (60 to 75 degrees) conditions which favor disease development.
Although common corn rust generally doesn't cause problems in sweet corn plantings, this season's unusual weather has led to an early appearance of this disease. If wet, cool weather conditions continue, rust could damage corn leaves and lead to reduced sweet corn yields.
Home gardeners who want to initiate a control program for common rust in their sweet corn plantings should consider application of fungicides to slow the progress of the disease.
If you have questions about your garden disease or insect control program, please feel free to check with us at your county Extension office.
Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.