Cogongrass is invading Mississippi

Published 12:34 pm Saturday, May 24, 2014

Cogongrass is rapidly spreading across Mississippi and is showing no signs of letting up. This very aggressive weed is capable of taking over low maintenance sites by out competing more desirable vegetation.  It can be seen all over Pearl River County blooming right now.

Cogongrass is commonly found in circular patches and can spread rapidly. The density of cogongrass patches (80 – 90 stems/ft2) and its aggressive nature allows it to out-compete other beneficial vegetation. Cogongrass is established in new sites by wind blown seed or movement of contaminates soils. Once a patch is established it spreads through rhizomes, a thick system of underground stems capable of producing new roots and shoots. This rhizome mass is extremely dense making this a difficult plant to destroy.

This grass is easily identified when growing in patches because of their circular nature. It also blooms and produces a white feathery seed head early in the spring (March to May). The offset midrib on the leaf blade is another characteristic that can be used as identification. Another key is the rhizome mat that forms in the upper four to six inches of the soil.

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Once this grass is positively identified every effort should be made to control it and prevent its spread. Glyphosate (Round-up or generic brand) and Arsenal are the two most effective herbicides for controlling cogongrass. To totally eliminate this grass the root mass has to be killed, so it may take multiple treatments over a couple years to control this pest. The most effective way to fight cogongrass is to prevent it from becoming established.


By Eddie Smith