by Bryon Walters
Phragmites australis, Common or Giant Reed, can be a very problematic invasive in wetlands and wet prairies. If left unchecked, it can form large monoculture, impenetrable jungles 6-10’ high. Usually nothing else will grow under the dense canopy. Large infestations can be controlled with high pressure, high volume, non selective herbicides, leaving the area brown and dead.
Small infestations should be dealt with as soon as possible. Here is a seep area that has about 24 stems.
September is a great time to deal with the stalks. You want to treat it before the large seed heads turn brown, ripening to the point of seed falling off. Early in the Fall, the seed heads may be young, green and unripe.
The only effective herbicides for treating Phrag are Glyphosate and Imazapyr. Both are non selective and will kill everything it drips on.
The high or good quality areas, the best approach to rid the Phrag and save the surrounding vegetation is a surgical approach.
First, starting in the back of a patch of Phrag, use hand pruners to cut the stalk off about knee or waist high. The lower the better, but personal comfort may dictate the height. Cast the long stalk you just cut with the seed head, off to the side laying it somewhat flat. If you just drop it where you cut it, it will remain upright and you will be confused and grab that stalk again thinking it needs to be cut. Use sharp pruners, I use Felco #2’s, to make a clean cut. You need to see the hollow hole in the remaining, standing stalk you just cut. If it is smashed closed, cut again just below your first cut. It should look like this.
Next, have a hand held bottle sprayer that is filled with 100% Glyphosate and a little blue dye. Slowly spray a straight stream into the hollow stem. It will hold various amounts of herbicide. You may want to practice spraying water into a straw before hand. The Phrag hole will be half the size of a straw hole. It takes a little practice and patience. When I cut the stalk I leave a small portion of a leaf sheath to use as a backboard when spraying into the hollow stem. It can stop the occasional overspray from running a stream of Glyphosate onto the ground or other vegetation. Sometimes Reed Canary Grass is all around and you don’t mind herbicide dripping on that. After getting in a rhythm, I may cut 3-5 stems in a group and then spray them. Don’t do more than that at one time because you may not find the stems. Get good with one’s and two’s before moving to larger groups.
Work moving backwards away from the stalk(s) you just treated. You do not want to step on, bending or breaking the stem you just treated. I can treat about 100 stems in an hour. I rarely cut more than that but on occasion I’ve had to.
An advisable follow up option would be to gather up the cut stems that are laying everywhere and put them on a pile. Working from the pile, I cut off all the seed heads and put them in a sack to carry off site. Even young green unripe seed heads could potentially ripen and reseed the area. It doesn’t take too long to do this. You’re reassurances are worth the little extra efforts.
I have successfully eradicated and eliminated Phragmites entirely from areas using this surgical approach. I’ve treated it with wonderful plants like Bog Goldenrod, Grass-of-Parnassus and Gentians growing right underneath the Phragmites. My follow up visits have shown zero damage to the native plants. Give it a try and you’ll be a doctor in no time.