Photographers: Forest and Kim Starr Affiliation: Starr Environmental Source: Bugwood.org Copyright: (CC BY 3.0)
Photographers: Karen Brown Affiliation: University of Florida Source: Bugwood.org Copyright: (CC BY 3.0)
Torpedograss (Panicum repens) is a perennial that can reach up to 3 ft. (1 m) tall, with long creeping rhizomes (horizontal underground stems), and torpedo-like rhizome tips. The leaves are flat or rolled, 10 in. (26 cm) long, 0.3 in. (5.3 mm) wide, with a white waxy covering. Leaf sheaths can be glabrous or hairy with a ligule (part of leaf located at the junction of the blade and sheath) covered by short hairs. Flowering occurs nearly year-round. When mature and fertile the florets are yellow or straw-colored.
Other common names for torpedo grass: Bullet grass, couch panicum, creeping panic, dogtooth grass, panic rampant, quack grass, and wainaku grass.
Torpedograss is highly resilient and can survive during extreme drought conditions, but prefers moist soil. Once established this grass is very difficult to eradicate.
This species is prohibited by TPWD as a harmful or potentially harmful exotic plant.
Propagation occurs primarily vegetatively by rhizome growth but seeds may also be dispersed by human activity or water. Torpedograss flowers nearly year-round, but it is variable in its seed abundance and viability.
Torpedograss was first documented in the US in 1876 in Alabama but it is believed to have been introduced to the United States earlier in Louisiana. This type of grass was used for agriculture because cattle did not trample it as easily due to its structure.
Native Origin: Africa and Eurasia
Habitat: Torpedo grass can be found on marshy shores or disturbed areas such as canals and poorly drained soil. Torpedo grass has no tolerance for cold weather and will die off following a frost thus limiting the possible range to the southern United States.
U.S. Present: AL, CA, FL, HI, LA, MS, NC, SC, TX
Chemical: Herbicide can be effective for controlling torpedograss in some situations. Glyphosate has proven effective for treating torpedograss above the water line but ineffective on plants growing in the water.
Preventative: Control can be accomplished to some degree by preventing the spread and fragmentation of rhizomes. This can be very difficult because if even a tiny fragment of rhizome remains, it will reestablish itself. Control of infestations near waterways will prevent long-range spread via water and this should be a priority.
Cultural: Weeds such as torpedo grass generally invade open or disturbed areas following a burn, clearing mowing, etc., so these areas are particularly vulnerable to invasion. Therefore, a healthy ecosystem with high species diversity may help to deter infestation.
Mechanical & Biological: At this time, there are no available biological control agents for torpedograss. There are limited agents being researched, and Dr. Charudattan at the University of Florida has been evaluating a species of fungus. Torpedo grass is very palatable for cows and goats, and grazing may be integrated in an overall management scheme. If mowing or tillage is used, care must be taken to prevent transport of rhizome or stolon fragments.
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Center for Aquatic and Invasive Plants. 2009. Panicum repens: Torpedgrass. University of Florida, IFAS.
Joedodibroto, R., L. S. Widyanto, and M. Soerjani. 1983. Potential uses of some aquatic weeds as paper pulp. Journal of Aquatic Plant Managment 21: 29-32.
Wilcut, John H., Roland R. Dute, Bryan Truelove and Donald E. Davis. 1988. Factors Limiting the Distribution of Cogongrass, Imperata cylindrica, and Torpedograss, Panicum repens. Weed Science 36(5): 577-582.