Keeping an Eye on Tropical Soda Apple Infestation on Your Pasture

April 2003
Dr. Martin B. Adjei - Range Cattle Research & Education Center

Tropical soda apple (TSA) has invaded pastures in south Florida since 1990. Serious efforts were made to control TSA in Florida in the mid 1990s but the enthusiasm eventually waned. Currently, there are more than 500,000 acres of TSA infestation in Florida.

Tropical soda apple is spread to new locations by cattle movement, wildlife, contaminated hay, grass seed and sod. It is on the list of Florida State's Noxious Weed according to Florida Law (Fla Admin. Code 5B-57-007) and as such it is unlawful to introduce, possess, or move TSA plants deliberately except under permit issued by Florida DACS or the USDA. Recently, some southern states including Georgia, Mississippi, and Alabama have considered passing legislation to regulate the movement of cattle from Florida to their states in order to stop the spread of TSA in southeastern USA. Such legislation, if adopted, would require the quarantine of Florida cattle at specified locations for up to one week during/prior to shipment. The expense of such confinement will be charged to the cattle owner and will increase cattle production costs in Florida.

Therefore, South Florida cattlemen need to pay greater attention to TSA infestation on their pasture and engage in renewed efforts at preventing, monitoring and controlling TSA as follows:

Sparse Stand

For sparse stands in south Florida, spot spray individual TSA plants in November with a 0.5% solution of Remedy (tryclopyr) + 0.1% non ionic surfactant. Wet foliage completely to the point of dripping with solution and use a color maker in the spray mix to ensure all plants are treated. Monitor the weed problem through winter and spot-spray new/regrowth TSA plants on that pasture again in February of the following year. Monitor plants through spring and if there are still some live TSA plants on the pasture, spot-spray a third time in May followed by continued monitoring through summer. Monitoring and repeated spot-spraying at about 60 d intervals over 2 years will prevent TSA fruits form maturing seed and help clean up a sparse stand of TSA on a pasture unless pasture is re-infested with seed introduced from outside.

Dense Stand

Dense stands of TSA on pasture in south Florida must be mowed repeatedly to a 3-inch stubble in November, February and April to prevent fruit setting/seed maturation. Repeated mowing every 50-60 days can in itself cause 50-60% mortality in mature TSA plants. After the April mowing, allow the TSA plants to regrow for about 60 days and broadcast spray 1 qt /A of Remedy + 0.1% non-ionic surfactant in June. Next, monitor TSA plants through September and spot-spray remaining plants in October with a 0.5% Remedy solution + the non-ionic surfactant and the color marker. Continue monitoring TSA for at least another year and spot spray emerging plants every 60 days as described for sparse stands until pasture is completely cleaned up.

There are hopeful signs that a variety of biological agents (insects, virus) for TSA control will soon become available to increase our arsenals on this noxious pasture weed. But for the meantime, prevention, monitoring and repeated spraying with Remedy provide the key to successful tropical soda apple control in south Florida.

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