South American weed hurts cattle industry.

• Position: Plant Pathology - Soda apple

It sounds like the name of an exotic new drink, but tropical soda apple has been more aptly described as the "plant from hell," say University of Florida. Gainesville researchers who have developed a natural way to control the rapidly spreading weed. "The highly invasive plant, which forms a dense and thorny thicket that is impenetrable to animals and people, has been classified by the Federal government as one of the nation's most noxious weeds," points out Raghavan Charudattan, professor of plant pathology with the institute of Food and Agricultural Sciences. "In Florida and seven southeastern states, it's literally taking over, displacing native plant species in infested areas."

He indicates that the weed native to South America, a serious environmental threat to natural areas and has become a major problem for the beef and dairy cattle industries. Sharp teems make the plant's foliage unpalatable, but livestock, wild animals and birds that eat the fruit help spread the seeds. Mature plants can produce 50,000 seeds that germinate under a wide range of conditions. Seeds also can be spread by compost, sod, and moving water.

Another concern, according to Charudattan, is that the cattle snipped out of Florida may harbor plant seeds in their...