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Corn Rust

Corn is one of the most heavily cultivated crops in the world, and is especially important to the economy of the United States, which ranks first in its production. Accordingly, any pests or diseases that may affect the growth or quality or corn plants are a serious concern.

Corn Rust

Losses can often be minimized by planting certain genetically engineered hybrids, and this practice has helped greatly reduce the severity of many threats to the crops. Disease-resistant hybrids are not always available for all types of corn, however. For instance, though there is rarely any need for additional control measures for rust among field corn crops when disease resistant varieties are grown, sweet corn and popcorn are much more susceptible to the fungal infection.

Corn rust is caused by two different fungi, Puccinia sorghi and Puccinia polysora, the former causing common rust and the latter being responsible for outbreaks of southern corn rust. Common corn rust, as is suggested by its name, is more widespread than southern rust, which is generally restricted to the southeastern United States. Both forms of rust are exemplified by the presence of brownish-red pustules on the stems and leaves of the corn plant, particularly in areas of new growth. The pustules contain numerous tiny spores that can infect new tissue or other plants when they burst open. The spread of rust is most pronounced under prolonged humid, relatively cool conditions.

Contributing Authors

Nathan S. Claxton, Shannon H. Neaves, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.