Tropical Soda Apple (Solanum viarum)
Miller, J.H., E.B, Chambliss, N.J. Loewenstein. 2010. A Field Guide for the Identification of Invasive Plants in Southern Forests. General Technical Report SRS-119. Asheville, NC. United States Department of Agriculture, Forest Service. 126 p.
Upright, thorny perennial subshrub or shrub, 3 to 6 feet (1 to 2 m) in height, with leaves shaped like northern red oak leaves, clusters of tiny white flowers, and green-to-yellow golf-ball size fruit. Fruit sweet smelling and attractive to livestock and wildlife. Remains green over winter in most southern locations. Caution: Fruit is poisonous.
Upright to leaning, much branched, hairy, covered with broad-based white to yellow thorns.
Alternate, 4 to 8 inches (10 to 20 cm) long and 2 to 6 inches (5 to 15 cm) wide. Margins deeply lobed (shaped like oak leaves). Velvety hairy with thorns projecting from veins and petioles. Dark green with whitish midveins above and lighter green with netted veins beneath.
May to August (year-round in Florida). Terminal small clusters of 5-petaled white flowers. Petals first extended, then becoming recurved. Yellow to white fused stamens projecting from the center.
Fruit and seeds
June to November (year-round in Florida). Spherical, hairless, pulpy berry 1 to 1.5 inches (2.5 to 4 cm). Whitish then mottled green ripening to yellow. Each berry producing 200 to 400 reddish-brown seeds.
Occurs on open to semishady sites. Viable seed in green or yellow fruit but not in white fruit. Reaches maturity from seed within 105 days. Persists by root crowns or green stems in warmer areas. Rapidly spreading by cattle and other livestock transportation and by wildlife-dispersed seeds as well as seed-contaminated hay, sod, and machinery.
Resembles horsenettle (S. carolinense L.), an 8- to 30-inch (20- to 80-cm) forb, which has similar but smaller fruit, long elliptic-to-ovate lobed leaves 3 to 5 inches (8 to 12 cm) long and 1 to 3 inches (2.5 to 8 cm) wide, and prickly yellow spines on stems and lower leaf veins but not on upper leaf. Also resembles, in stature and habitat, the closely related nonnative sticky nightshade (S. sisymbriifolium) which has deeply lobed lanceolate leaves and bright-red ripe fruit initially enclosed in a prickly husk.
History and use
Native to Argentina and Brazil and introduced into FL in the 1980s. No known use. A Federal listed noxious weed with an eradication program underway.
Found in dense infestations in FL and the southern portions of MS, AL, GA, and SC, with outlying infestations in west NC and central TN. Mainly occurs in pastures and moving into the forest margins and openings.
- Do not allow cattle to eat fruit.
- Treat when new plants are young to prevent seed formation.
- Cut and mow when fruit are not present (cutting and mowing is used for stopping fruit production but will not control plants).
- Collect and destroy all fruit.
- Manual pulling is hindered by thorny branches and limited to new seedlings.
Recommended control procedures for isolated sightings
- Thoroughly wet leaves and stems with one of the following herbicides in water with a surfactant at times of flowering before fruit appear: Garlon 4 (or Remedy® in pastures), Tordon K* ‡, or Arsenal AC* as a 2-percent solution (8 ounces per 3-gallon mix); Milestone VM* as a 0.5-percent solution (2 ounces per 3-gallon mix); Tordon 101* ‡ as a 4-percent solution (1 pint per 3-gallon mix); or a glyphosate herbicide as a 3-percent solution in water (12 ounces per 3-gallon mix).
- If mowing is used to stop fruit production, delay herbicide applications until 50 to 60 days to ensure adequate regrowth.
* Nontarget plants may be killed or injured by root uptake.
‡ When using Tordon herbicides, rainfall must occur within 6 days after application for needed soil activation. Tordon herbicides are restricted use pesticides.