Tropical Soda Apple (Solanum viarum): A New Weed Threat in Subtropical Regions

In 1990, a broadleaf weed growing on a cattle ranch in Hendry County in southwest Florida was identified as tropical soda apple (Solanum viarum Dunal), a species native to Argentina and Brazil (5) (Figure 1). Tropical soda apple (TSA) was apparently collected in Florida from Glades County in 1988 (University of Florida Herbarium) but was observed on the Hendry County ranch as early as 1987. Having foliage unpalatable to livestock, this noxious weed can infest a pasture or rangeland within one to two years resulting in lower stocking rates (animals per hectare). However, livestock and wildlife (feral hogs, deer, raccoons) will eat the fruit and disseminate the seed via feces. Fruit production occurs throughout the year (primarily September through May) thus providing high numbers (40000 to 50 000 per plant) of viable seed (75% germination) for seed dispersal. Our objectives are to alert those concerned with weed control of the presence of TSA in subtropical regions of the U.S., to discuss the ecology and taxonomy of this weed, and to indicate areas for future research.