August is Cogon Grass treatment time

If you have cogon grass on your property, now is the time to start treating it with herbicide. This perennial grass first introduced in the U.S. in 1912, from the tropical and subtropical regions of the world is an aggressive, invasive species. Early detection and multiple treatments are keys to eradicating cogon grass.

Cogon grass in flowerCogon grass is often fairly easy to identify. Right now it is bright green and often presents as several clumps of grass that cover an area in a circular pattern. Cogon grass spreads by rhizome with leaves that are bunched at the soil level, without any branching blades above the ground. An easy indicator is an off center mid-rib on each grass blade. The rhizomes form thick mats under the soil and produce biochemicals that inhibit the growth of other plants, which is why we typically see very little other vegetation within a cogon grass infestation.

Cogon grass if often seen growing along road shoulders and many properties have populations that spread from there. In Georgia, the Georgia Forestry Commission if contacted, will map, treat, and monitor the site. In Leon County, Florida, there is a county branch dedicated to the treatment of the right of ways. If you have cogon grass that spread onto your property from the shoulder, you can coordinate spraying by contacting the county and requesting treatment of road shoulder simultaneously. Some counties offer cost share programs to help with treatment, see web links below. Cogon grass also gets introduced by contracted work, hitchhiking on heavy equipment. It is important that any heavy equipment you have coming onto your property is properly cleaned before you allow access. Typically, if cogon grass is introduced it often appears first in disturbed soil and logging decks. Disturbing these areas will spread the rhizomes and create new populations of the plant.

We recommend treating the affected area and a 30-foot buffer around the cogon grass with 24 to 30 ounces Arsenal + 2 quarts Glyphosate + 1 quart of Methylated seed oil + 50 gallons water/acre. You have to be very careful with Arsenal as it is soil active, persists in the soil for a long time, and will kill any hardwoods in the area including mature trees. The effects from spraying Arsenal take many months to appear. Therefore, we find it helpful to add 2 quarts of Glyphosate to the mix, which will brown the cogon grass but not kill it, allowing you to see any areas you missed when applying your herbicide mix. Other herbicides have also been shown to be effective, but be sure to apply according to label instructions (Imazapyr is also proven effective, 24-48 oz Imazapyr +2 quarts Glyphosate + 1 quart of Methylated seed oil + 50 gallons water/acre). It is critical to monitor the site for many years post treatment, it may appear eliminated, only to resprout up to 3 years later.

Over the past 100 plus years cogon grass in the U.S. continues to be a problem. It claims the title of the “Top 10 Worst Weeds in the World.” Persistent spraying over multiple years is the best way to keep this longtime invasive species from taking over your property.

Cogon grass

Photo top right. Cogon grass is easy to identify when in flower, the white, fluffy seed heads are very visible. Photo above. Encroachment of cogon grass onto a property from a right of way is a common way it gets on private property.

In Florida:

In Georgia:

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