Photographers: Forest and Kim Starr Affiliation: Starr Environmental Source: Bugwood.org Copyright: (CC BY 3.0)
Torpedo grass (Panicum repens) is a perennial that can reach up to 3 ft. (1 m) tall, with long creeping rhizomes, and torpedo-like 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 membranous ligule covered by short hairs. Flowering occurs nearly year round. When mature and fertile the lemma palea are yellow or stramineous.
Torpedo grass is highly resilient and can survive during extreme drought conditions, but prefers moist soil. Once established this grass is very difficult to eradicate.
Propagation occurs via seed dispersal or plant division with division rhizome extension used as the most effective method. Torpedo grass flowers nearly year-round, but variable in its seed abundance and viability.
Torpedo grass was first collected in 1876 in Alabama, but is believed to have been introduced to the United States first 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
Other common names for torpedo grass: Bullet grass, coastal bermuda grass, couch panicum, creeping panic, dogtooth grass, panic rampant, quack grass, and wainaku grass.
Preventative: Control can be accomplished by preventing the spread and fragmentation of rhizomes. This can be very difficult because if even a tiny fragment of rhizome is left in an area, it will reestablish itself. Control of infestations near waterways will prevent long-range spread via water and this should be a priority. If mowing or tillage is used, care must be taken to prevent transport of rhizome or stolon fragments.
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 will help to deter infestation.
Mechanical & Biological: There are limited agents being studied for biological control of torpedo grass, although 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.
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Center for Aquatic and Invasive Plants. 2009. Panicum repens: Torpedo Grass. 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.