Torpedograss Study at Wellington Environmental Preserve

Scientific Name: Panicum repens
Common Name: Torpedograss

What is torpedograss?
Torpedograss (Panicum repens) is a highly invasive aquatic grass that has invaded many lakes, wetlands, retention ponds, and storm water treatment areas in Florida, including Wellington Environmental Preserve. It was historically planted in Florida as a forage grass in the 1950s but rapidly spread into aquatic and wetland sites and has been problematic for several decades.

Why is it a problem?
Torpedograss forms very dense stands that exclude many native emergent plants. This can result in a reduction in native species cover and reduced habitat quality for many other species that live in wetlands.

Why is this management study being done?
There are very few control strategies that are effective for torpedograss. Hand-pulling is feasible only for very small stands. Mechanical removal with aquatic harvesters is nearly impossible for this species and is very costly. There are no biological control agents that are approved for use to control torpedograss. Cattle will graze it, but they will not effectively control it. Currently, only two herbicides provide useful control of torpedograss and they are glyphosate and imazapyr. Both are very effective but are also non-selective, meaning they will injure or kill other plants they contact. Retreatment of infested areas is often necessary and more selective herbicides are needed to protect native plants in treated areas.

To address this issue, we are testing a (new) herbicide for use on aquatic invasive grasses. The herbicide active ingredient is fluazifop-p-butyl, which has actually been registered for use in agriculture and non-crop settings for over thirty years. However, in 2016, it received an experimental use permit for testing in aquatic systems in Florida. Fluazifop provides selective control of many grasses without harming other non-grass plants. If effective on torpedograss, it could be very useful in improving aquatic and wetland habitats in the Preserve and many other water bodies and natural areas in Florida.

Why are the restrictions needed?
The restrictions in the experimental use permit regarding swimming, fishing, irrigation, and drinking water in the treated area are an extra measure of safety since the product has not yet been labeled for use in aquatic systems by the EPA. The total area treated in this study is 0.1 acres and is located on the northeast side of the preserve, where none of these activities are likely to occur.

Who can I contact if I have additional questions?
The Principal Investigator’s contact info can be found below.

Dr. Stephen F. Enloe
Associate Professor
Agronomy Department/Center for Aquatic and Invasive Plants
7922 NW 71st St.
Gainesville, FL 32653