Native to: tropical and subtropical regions of Europe, Asia, and Africa
The common name torpedograss refers to this grass’ sharply pointed or torpedo-like growing tips. It was introduced to the United States before 1876, primarily through seed used for forage crops. In the early 1900’s the United States Department of Agriculture imported and distributed torpedograss seed for planting in pasturelands, providing forage for cattle. It can now be found in cultivated and abandoned fields, open ground, gardens, lawns, and landscape planting beds and also thrives in aquatic habitats from lakes to marshes. Considered one of Florida’s most troublesome invasive grasses, it can be found in over 70% of the state’s public waters.
Habit: perennial grass that can grow up to 40 inches tall from creeping rhizomes (underground stems that form lateral shoots and roots) and stolons (aboveground stems that creep across the ground or float in aquatic environments).
Leaves: hairy leaf sheaths and hair on the upper margins of the leaves. Leaf blades are stiff, linear, flat or folded; the surface often with a waxy or whitish coating.
Flowers: panicle-type inflorescence, 3-9 inches long.
Distribution in Florida: throughout entire state.
Seed viability in Florida has been determined to be low to none and it primarily spreads vegetatively by rhizomes and stem fragments, which can form new plants. It can easily be moved to new areas on mowers and other heavy equipment as well as boats and aquatic equipment. Large infestations found in Lake Okeechobee displace close to 7,000 acres of native marsh. Torpedograss management costs approximately $2 million a year in flood control systems and it is also a major problem for the citrus and golf course industries. The denseness of the mats may impede water flow in ditches and canals and restrict recreational use of shoreline areas of lakes and ponds.
Torpedograss can be extremely difficult and expensive to control. Prevention should be part of every management plan. For torpedograss, the spread of rhizomes can be limited by controlling populations near waterways, properly cleaning machinery such as lawnmowers and boats, and only accepting materials like soil, mulch, and hay from certified sources.
Maintaining a healthy ecosystem with native species diversity may limit the amount of open and disturbed habitat available for torpedograss establishment.
Only moderately effective. Mechanical methods include tillage, digging, mowing and burning; however, these methods can result in numerous rhizome fragments that can sprout and produce aerial shoots. Hoeing and hand weeding are also known to be ineffective due to its rapid growth from underground rhizomes. Continuous tillage can be effective under the right conditions, such as soil conditions, climate, and the depth of tillage. In many natural areas, particularly wetlands, tillage is impractical and difficult to use. Digging the rhizomes out has been attempted in few studies, but in large areas it is impractical, expensive, and time-consuming, and it usually results in further spread of rhizome fragments. However, this method may work in very small areas, such as landscape beds where the infestation is confined. Mowing is only marginally effective, and torpedograss can tolerate grazing and trampling. Fire can be used to destroy the aboveground vegetation, but the rhizomes are protected underground and can resprout.
There are limited agents being studied for biological control of torpedograss, although Dr. Charudattan at the University of Florida has been evaluating a species of fungus. Torpedograss is very palatable for cows and goats, and grazing may be integrated in an overall management scheme.
Postemergence herbicides are the most common and widely used method of torpedograss control. Two of the most effective herbicides for torpedograss control are glyphosate and imazapyr (McCarty et al. 1993). While glyphosate can be used as in landscape planting beds if applied as a directed application, imazapyr is not labeled for use in landscapes and application can result in severe injury or death to landscape ornamentals. In areas where glyphosate can be applied without contacting nearby ornamental plants, it can be applied as a 2% to 3% v/v solution; however, repeated applications are often needed for complete control (Nir 1988). In cases where torpedograss is growing through the canopy of shrubs (Figure 6), graminicides such as fluazifop-P-butyl (Fusilade II), which is labeled for torpedograss suppression, or sethoxydim (Segment II), can be applied as an over-the-top application to most broadleaf ornamental plants. However, these herbicides are typically less effective than glyphosate and multiple applications are usually needed for long-term control (Enloe et al. 2018). Because torpedograss primarily spreads via rhizomes, preemergence herbicides are not an effective option.
Consult your local UF IFAS Extension for further assistance with management recommendations. Additional information can be found in the EDIS Publication Integrated Management of Non-Native Plants in Natural Areas of Florida and Biology and Management of Torpedograss in Ornamental Landscape Planting Beds