Tropical soda apple

Solanum viarum
Shrub
Alternate
Simple
White
Green

Tropical soda apple is a major pest in Florida, where it has invaded at least 500,000ha of land and costs landholders millions of dollars each year in control costs and lost production. Queensland has only a small number of isolated tropical soda apple infestations, but the species has the potential to become a pest in coastal and subcoastal Queensland.

Tropical soda apple is a prohibited invasive plant under the Biosecurity Act 2014.

Common names 
Also known as: sodom apple,
Family 
Solanaceae
Deciduous 
No
Flowering time 
Through out the year
Native/Exotic 
Exotic
Origin 
Native to South America
Notifiable 
Yes
State declaration 
Category 1
Council declaration 
As per State Declaration
Known distribution 

First detected in Queensland in November 2010 near Coominya in South East Queensland.Currently small number of isolated infestations in Queensland. Further infestations have been found in NSW at Wingham, Grafton, Bellingen, Coffs Harbour, Bonalbo, Casino, Murwillumbah and Wauchope. 

Habitat 

Prefers open, disturbed sites, especially pastures and areas around cattle yards.
Prefers coastal, high-rainfall habitats in tropical and subtropical areas.

Habit 

Tropical soda apple is an upright, branching, perennial shrub growing to 2 m in height. It has broad-based, straight, cream-coloured prickles to 12 mm long scattered on most plant parts.

It reduces biodiversity by displacing native plants and disrupting ecological processes. Its foliage is unpalatable to livestock, thus reducing carrying capacities, however cattle eat the fruit and spread viable seeds in manure. Thorny thickets of this plant create a physical barrier for animals preventing access to shade and water. The plant is a host for many diseases and pests of cultivated crops, and it contains solasodine which is poisonous to humans.

Stem and leaves 

Leaves are mostly 10–20 cm long and 6–15 cm wide and deeply disected. The upper and lower leaf surfaces are densely covered in short hairs; mid-veins and primary lateral-veins are cream-coloured on both sides of the leaves. Stems have thorn-like prickles up to 12mm long

Flowers and fruits 

Flowers are white, 1.5-2 cm wide, with 5 recurved petals and white to cream-coloured stamens.. They occur in clusters of 3–6 off a short stem. Immature fruits are smooth, round, mottled light and dark green like a watermelon. Mature fruits are yellow, 1-3cm in diameter, with leathery skin surrounding pale green, scented pulp, each containing 180 to 240 seeds. Seeds are pale brown, tear-shaped, 3mm across. 

Reproduction and dispersal 

Seeds spread primarily by cattle but also by birds, feral pigs, deer and contaminated hay. Fruit float and move in water along creeks and drainage lines. Tropical soda apple can also regenerate from its root system. If not controlled a few plants will form a hectare sized thicket in 6 months, with each plant producing around150 fruit.

Similar species 

Devils Apple (Solanum capsicoides), Devils fig (S. torvum), Giant Devils fig (S. chrysotrichum), Apple of Soddom (S. linnaeanum)