Coast Gardener
Torpedo Grass Control in Landscape Beds
Coast Gardener Newspaper and Web Column - November 3, 2008
Torpedo grass (Panicum repens) is an aquatic plant originally imported for it forage capacity. Unfortunately, like many plants imported for one purpose, torpedo grass is causing major headaches for the homeowner in the lawn and landscape beds.
On
top of the ground this weed produces sharply pointed stolons which give
the plant its name. These stolons can grow up to three foot high and,
if it finds support, even higher. This is evident in the landscape when
it is common to see torpedo grass coming out the top of evergreen hedges.
Torpedo grass spreads through the formation of underground stems called rhizomes. When we pull the weed by hand we actually are encouraging the spread of the torpedo grass because the rhizome is not totally removed, becomes fractured, and forms more roots from the remaining pieces in the ground.
Torpedo grass is very susceptible to glyphosate (Roundup), but spraying this compound in the landscape is problematic since over spray will kill our desirable plants.
One solution is to target and apply the glyphosate only to the torpedo grass. Purchase a pair of long kitchen-type rubber gloves and inexpensive cotton gloves. Put on the rubber gloves followed by the cotton gloves. Dip the cotton glove in a glyphosate solution (1 to 2% ready to use) and touch the torpedo grass stolons. This gives you control where the herbicide is applied.
Another method I have found is illustrative on how plants absorb materials through the leaves. Wearing rubber gloves for protection, pour a couple of ounces of ready to use glyphosate into a small plastic zip bag. Place the terminal end of a torpedo grass stolon into the zip bag making sure it is in the solution, carefully squeeze excess air out and zip close. Gently place the zip bag on the ground so as not to spill. The torpedo grass will take up the solution.
This works so well because during the fall the torpedo grass is storing carbohydrates and other nutrient reserves in the roots for growth next year and the glyphosate is transported to the roots for a more effective control measure.
Published November 3, 2008
Written by Dr. Gary R. Bachman, Assistant Extension Professor of Horticulture, Coastal Research & Extension Center.