Tropical soda apple

Solanum viarum

Tropical soda apple

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Introduction

Solanum viarum or Tropical soda apple (TSA) is a native to Brazil and Argentina. Since its discovery in the United States, it has been found in many southern states including Florida, North Carolina, and Mississippi. It was first collected in Glades County, Florida in 1988. It is estimated that approximately one million acres of pasture, sod farms, forests, ditches, natural areas, etc. are covered with TSA in Florida.

Tropical soda apple is extremely prolific, producing roughly 40,000 to 50,000 seeds per plant. Seed is spread primarily via livestock and wildlife, such as raccoons, deer, and birds that consume the fruit. If TSA is not controlled in pastures it can lead to reduced yields in terms of lower stocking rates, lower forage quality, and lower profitability. Dispersal is also accomplished through contaminated equipment, hay, seed, sod, and composted manure. Cattle, sod, as well as other transported goods carry the potential of spreading this invasive weed to other parts of the state and country. This concern and its rapid spread throughout Florida caused TSA to be placed on the Florida Noxious Weed List in 1994 and the Federal Noxious list in 1995.

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Description

Tropical soda apple is in the family Solanaceae, or Nightshade family. This family also contains potato, eggplant, and tomato. TSA is an herbaceous perennial, growing 3-6 feet tall. Leaves are pubescent, deeply divided into pointed lobes. White to yellowish thorns up to 0.4 inch-long are found on the stems, flower stalks, leaves (both upper and lower surfaces), and calyxes. Flowers are white with yellow stamens and are found on the stem below the leaves. Fruits are globular in shape and are green in color when young, yellow at maturity.

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Impacts

The most effective means of controlling TSA is the prevention of fruit production. In addition, tropical soda apple has been regulated by the prevention of cattle movement and transport of contaminated seed, sod, hay, manure, and soil from infested areas to areas that are not infested.

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Management

 

Preventative:

The most effective means of controlling TSA is the prevention of fruit production. In addition, tropical soda apple has been regulated by the prevention of cattle movement and transport of contaminated seed, sod, hay, manure, and soil from infested areas to areas that are not infested.

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Cultural:

Maintaining a quality turf through proper fertilization, watering, insect and disease control is the first step in tropical soda apple suppression. Proper cutting and/or stocking rate will also maintain good growing conditions for the forage and keep TSA from gaining a foothold.

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Mechanical:

Mowing will greatly suppress the growth of tropical soda apple and may kill seedling plants. Properly timed mowing can also delay fruit production. However, mowing alone will not effectively control mature plants.

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Biological:

Tropical soda apple is a member of the Solanaceous family, which also includes potato, eggplant and tomato. Gratiana boliviana is an adventive tortoise beetle that feeds specifically on the foliage of TSA. The Technical Advisory Group (TAG) for Biological Control Agents of Weeds approved the release of this biological control agent from quarantine in Apri12002. This beetle has the potential to reduce the competitive advantage of TSA, which will enable native species to flourish.

Another biological control agent that is under investigation is the flower bud weevil, Anthonomus tenebrosus. This weevil develops inside flower buds causing premature abortion of flowers, leading to the inhibition of fruit production. Requests for the release of the flower bud weevil will be submitted to the TAG if further testing indicates this species is specific to TSA. In addition, Dr. Charudattan at the University of Florida is developing a plant pathogenic virus specific to TSA. Preliminary results indicate good control, but further testing is necessary to ensure specificity.

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Chemical:  

For sparse infestations including pastures, vegetable fields, sod fields, hammocks, ditch banks, and roadsides TSA plants should be individually sprayed for control and to prevent additional seed and fruit production. Herbicide treatments should be applied to ensure adequate coverage, resulting in maximum uptake and control. Treated areas should be monitored on a monthly basis. New seedlings should be sprayed and TSA should not be allowed to set fruit. This is an important preventative control that will help limit the spread of this weed. Triclopyr-ester and aminopyralid (Milestone VM) at 0.5% and 0.1% solution, respectively, are recommended. Regardless of which herbicide is used, it is important to spray the entire plant. Spraying only half the plant will result in poor control.

Aminopyralid containing herbicides products are the most effective for controlling dense infestations. Milestone VM at 7 fl. oz/A will control emerged plants and provide residual control of germinating seedlings for approximately 6 months after application. In areas where the residual activity of aminopyralid can not be tolerated, triclopyr-ester can be used. If triclopyr-ester is to be used, mowing should be performed first and an herbicide application should follow 50 to 60 days after the first mowing. Broadcast applications of triclopyr-ester (Remedy) should occur at 1.0 quart per acre in enough water to thoroughly cover the plants.

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References and Useful Links:

Environmental Protection Agency

Florida's Division of Plant Industry

Florida's Cooperative Extension Electronic Data Information Source

University of Florida

United States Department of Agriculture (USDA)/ Animal and Plant Health Inspection Service (APHIS)

Bryson, Charles T., John D. Byrd, Jr., and Randy G. Westbrooks. 2002. Tropical soda apple (Solanum viarum Dunal) in the United States. Mississippi Department of Agriculture and Commerce -Bureau of Plant Industry.

Medal, J. C., J. P. Cuda and D. Gandolfo. 2002. Classical Biological Control of Tropical Soda Apple in the USA. ENY -824. Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

Mullahey, J. Jeffrey. 1993. Tropical Soda Apple: A New Noxious Weed in Florida. Fact Sheet WEC 7. Department of Wildlife Ecology and Conservation, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

Mullahey, J. J. and J. T. Ducar. 2002. Weeds in the Sunshine: Tropical Soda Apple (Solanum viarum Dunal) in Florida. SS-AGR-50. Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.

 

Excerpted from the University of Florida, IFAS Extension, Circular 1529, Invasive Species Management Plans for Florida, 2008 by:

Greg MacDonald, Associate Professor Jay Ferrell, Assistant Professor and Extension Weed Specialist
Brent Sellers, Assistant Professor and Extension Weed Specialist
Ken Langeland, Professor and Extension Weed Specialist Agronomy Department, Gainesville and Range Cattle REC, Ona
Tina Duperron-Bond, DPM – Osceola County
Eileen Ketterer-Guest, former Graduate Research Assistant

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