Tropical soda apple (TSA) is established in the West Indies, Mexico and Central America, as well as tropical regions of Africa, Asia and Australia. The “apples” or fruit of the tropical soda apple are small spheres about 6 cm in diameter that look just like miniature watermelons. Tropical soda apple is an aggressively invasive spiny shrub that produces many thousands of seeds that disperse rapidly over a wide area.
I. Appearance and Characteristics
Solanum viarum, the tropical soda apple, is a perennial shrub native to Brazil and Argentina with a prickly stem and prickly leaves. The fruit is golf-ball-sized with the coloration of a watermelon. It is considered an invasive species in the lower eastern coastal states of the United States and recently on the Mid North Coast of Australia.
The mature fruits are smooth, round, yellow and ¾ to 1 1⁄4 inches in diameter with a leathery-skin surrounding a thin-layered, pale green, scented pulp and 180 to 420 flattened, reddish brown seeds. Each plant is capable of producing 200 or more fruit per year. Tropical Soda Apple (Solanum viarum) usually grows to 3–6 ft tall.
Solanum viarum is native to Brazil and Argentina, and was first discovered in the United States in 1988, having probably been introduced through contaminated seed or other agricultural products. It crowds out native species and forage for livestock Its habitat is terrestrial, in fields, rights-of-way, and open forest. It is spread by livestock and wildlife, such as raccoons, deer, feral hogs, and birds feeding on fruits.
It is classified as a noxious weed or plant in Alabama, Florida, Mississippi, North Carolina, Texas, and Vermont, and in California and Oregon it’s a quarantine pest. It is a prohibited noxious weed in Arizona and Minnesota; Prohibited in Massachusetts; and a plant pest in South Carolina and Tennessee. It is also listed as a tier 1 noxious weed in Virginia, along with giant hogweed.
Since its introduction into the U.S., tropical soda apple has spread rapidly, and currently infests an estimated one million acres of improved pastures, citrus groves, sugarcane fields, ditches, vegetable crops, sod farms, forestlands (oak hammocks and cypress heads), natural areas, etc. in Alabama, Florida, Georgia, and Mississippi. Although it can be a threat to a variety of habitat, it tends to be most problematic in pastures in the Mid South.
It is controlled by triclopyr herbicide. Gratiana boliviana, the tropical soda apple leaf beetle, has been used successfully as an agent of biological pest control to reduce the abundance of this plant in the United States, particularly in Florida.
II. How to Grow and Care
Tropical soda apple requires vigilant management due to its status as an invasive species. Key to its care is the need for regular monitoring to prevent uncontrolled spread, as well as the implementation of effective containment strategies. It is a resilient plant that can thrive in a variety of environments, which necessitates an active approach to management and removal.
Sunlight
Tropical soda apple thrives best in conditions of full sun exposure, which ensures robust growth and optimal health. The intensity of direct sunlight suits the plant’s needs for photosynthesis and energy production. While tropical soda apple demonstrate tolerance for partial sun, prolonged periods in such light can lead to reduced vigor and potential stress responses. The plant has evolved adaptive mechanisms, such as adjusting leaf orientation, to maximize light absorption when necessary. Outdoors, tropical soda apple should be positioned where it can receive uninterrupted sunlight for the majority of the day to foster its developmental processes and maintain its vitality.
Watering
Tropical soda apple is a plant that thrives in humid environments, exhibiting strong adaptability to various water conditions. It demonstrates relative balance in its water habits, neither requiring excessive moisture nor displaying notable drought tolerance. The watering frequency for this plant should be once every 2-3 weeks. Typically grown outdoors, tropical soda apple has a robust growth cycle that’s influenced by rainfall patterns, making it an intriguing study of nature’s water economy.
Fertilizing
For tropical soda apple, use balanced nutrition fertilizers to support its overall growth and high-nitrogen options for lush vegetation. Fertilize monthly during growing seasons for optimal health and vigor. Apply per product instructions; excess can harm tropical soda apple. Seasonal variations influence needs: decrease frequency in winter. Practical tip: dilute fertilizer to prevent root burn and ensure even distribution for effectiveness.
Propagation
Tropical soda apple is a perennial shrub that can be propagated effectively through cuttings. Gardeners should select healthy, disease-free stems and cut them into segments ensuring each piece has several nodes. The cuttings root best in a warm, moist medium that allows for adequate drainage. It’s important to maintain high humidity around the cuttings during the initial rooting period. Once rooted, transplant the young plants to their final location, providing support as needed until they establish.
Transplanting
The best time to transplant tropical soda apple is when the warmth of spring gently unfolds into the landscape, offering optimal growth conditions. Choose a sunny location with well-drained soil. Gentle handling during the move ensures the tropical soda apple thrives in its new setting.