Digging, Burning Thwart Soda Apple Weed

Other than herbicides, the best way to prevent the spread of the noxious weed tropical soda apple (Solanum viarum) is to remove the plant and burn it, Agricultural Research Service scientists report. Clipping or mowing the weed before it produces fruit is also effective.

The tropical soda apple now covers about 1.5 million acres in the Southeastern United States, having been spread primarily by cattle, but also by deer and other wildlife. These animals love to eat the fruit. It passes through their digestive tract, and the seeds are then spread in the manure.

The weed can be found growing in pastures, urban areas, vegetable crops and natural areas in Florida, Georgia, South Carolina, North Carolina, Tennessee, Alabama, Mississippi and Louisiana. It has also been found in Puerto Rico.

For 32 sites in 13 counties in Mississippi, botanist Charles T. Bryson, with ARS’ Southern Weed Science Research Unit in Stoneville, Miss., provided information to landowners on how to dig up the tropical soda apple plants, bag them and burn them to ensure all plant parts are truly dead. The weed persisted at only six sites.

But don’t try to bake them in an oven or a microwave, because the plant and its fruit produce glycoalkaloids, a substance toxic to humans.

The best cultural practice for homeowners is removing single plants by hand or clipping or mowing multiple plants. Mowing the weeds a couple of times early in the season helps prevent fruit and seed production. Homeowners can obtain 80-90 percent control by mowing every 45-60 days.

Once the plant is full of fruit, however, Bryson cautions homeowners that seeds could spread by mowing. Homeowners should contact a county extension agent first to identify the weed and then eradicate it as soon as possible.

Bryson is undertaking new research looking at biological control agents as a means to control this weed. ARS is the chief scientific agency in the U.S. Department of Agriculture.

Scientific contact: Charles T. Bryson, ARS Weed Science Research Unit, Stoneville, Miss., phone (601) 686-5259, fax (601) 686-5422, [email protected].