VIDALIA — Asian soybean rust — a devastating crop fungus — has been confirmed in nearby Rapides and Avoylles parishes.

The instances of rust were found in soybean sentinel plots, according to the U.S. Department of Agriculture.

Soybean rust, introduced into the United States in the mid-1970s, is spread by wind-borne spores, and many believe it was originally blown to the United States from South America by Hurricane Ivan.

The disease causes plants to defoliate prematurely, and it also affects the number of seeds in each soybean pod, leading to lower yield and early plant death.

The fungus thrives in conditions of extended wetness with temperatures between 59 and 82 degrees Fahrenheit. If the temperature rises above 86 degrees Fahrenheit, the fungus’ growth will be slowed or even stopped.

Some varieties of soybean have been developed to be partially resistant to the disease, and it can be managed somewhat with fungicides.

The fungus can be detected early on when small lesions — which will in later stages turn red and brown — appear near the veins on leaves.

In its later stages, rust develops cream to tan spore-filled, egg-shaped pustules.

The U.S. Department of Agriculture recommends wearing disposable clothes for fungicide spraying if rust is detected in a field because rust spores can cling to clothing.

The U.S. Department of Agriculture also requests anyone who finds rust in their fields take a sample and send it to the nearest agriculture testing station to determine what strain of rust it is to help develop management programs.