By Bryon Walters, Conservation Contractor, near Mendota Illinois
In early Spring 2018, I wanted to reduce Reed Canary Grass (Phalaris arundinacea) in a very nice, perpetually wet seep area. This area in late May will be solid Skunk Cabbage, Marsh Marigolds, Blue Joint and Sedges. I wanted to hit the RCG as it was 6-10” high and before the natives sprawled about.
I made a broadcast spray mix consisting of Aqua Glyphosate @ 2% plus Imazapyr (Habitat) @ 1%. It’s vital to add an Aquatic Surfactant to the mix. About 0.25%. That’s 1/4 of 1%.
I adjusted my nozzle to spray a very narrow cone pattern so I could pinpoint my spraying of Reed Canary Grass growing in between existing Skunk Cabbage and Marsh Marigolds. Keep in mind that this is a non-selective, very unforgiving mix. If you accidentally spray something good, immediately snip off the sprayed leaf. These areas had standing water in between plants. Working in a deliberate pattern, I started in the far back corner of the seep, walking back out of the sprayed areas. Do not walk through areas that you just sprayed. I would return 7 days later and I could see yellowing of the Grass clumps I sprayed. Just as importantly, I could see the bright green of the clumps I missed. I then sprayed those green clumps. Returning again in another 7 days, I only had to go in where I saw green clumps that were missed, twice. It happens when you spray a several acre plot that has lots of fallen trees and obstacles to work around.
It’s a good feeling to leave the area for the season after seeing all dead or dying Reed Canary Grass.
These spots will remain bare for most of the year.
The following year, Spring 2019, as to be expected, there were a few new green clumps of RCG. They were treated in the same fashion.
The important part is to work slow and methodically. You can greatly reduce Reed Canary Grass in an area using this method. The natives will quickly fill in the void of the dead RCG.
HI Bryon, Would you have a recommendation for a grass-specific herbicide to use in this same situation? Thank you for sharing.
Have you considered spraying RCG with a grass only herbicide like Clethodim or Poast instead of a nonselective herbicide like glyphosate (Roundup)?
BK here: I emailed Bryon asking him if he can reply. I know he has used grass specific herbicides.
Hello, we have to follow labels and the products you mentioned are not allowed to be sprayed over or near water. Also, those products, in my experience, only top kill grasses. You need a systemic product to eradicate RCG. New clumps may emerge the following year, likely from seed.
Hi Byron, I have been attempting to kill RCG for about 5 years now primarily using 3% Rodeo, andin the dry areas Clethodim and Fusilade DX. I have not tried 2% Rodeo (aquatic Roundup) with 1% Habitat. I am pretty comfortable with the job the Rodeo has done killing RCG. What does adding the Habitat do for you as my experience is that it leaves a dead zone for a year. Do you think it kills the lateral dormant bud better? My experience with Clethodim and Fusilade DX is that you get a lot more re sprouts with grass selective and Rodeo kills it about 50% better. So you are never sure with grass selective whether it is only top killing it as you say or the dormant lateral bud is re sprouting. The biggest hole in my understanding is that dormant lateral bud that re sprouts when the original Rhizome is killed. When does there stop having a dormant lateral bud? Is that only for mature stands of RCG as does the re sprout create another lateral dormant Rhizome only in the second year? Eventually it stops re sprouting but when? Have not seen any literature on this. Thanks, John Ayres
The first picture shows how damage to non-target plants will occur even if they are not directly sprayed. The smaller skunk cabbages look the most impacted and may not survive. Anything within up to a foot of a glyphosate application during the growing season can be impacted. I’d suggest covering the skunk cabbages, or anything else you don’t want impacted near where spraying is occurring, with clear plastic until rain has washed the excess herbicide away. This may not completely eliminate impacts to adjacent desirable vegetation, but it will reduce it considerably.
There are a couple grass specific herbicides I’ve used. Intensity is one and Fusillade another. I also use a dose of AMS to give it a bit more jolt. It may take a couple years of applications with these herbicides and also employing prescribed burns to get the RCG under control. The biggest collateral damage issue is with blue joint grass that is a cool season grass that has many same properties as the RCG. Good thing is that sedges are not bothered by these herbicides and can actually thrive when competition is suppressed. Good luck.
Again, in Illinois you would be in violation if you used anything other than aquatic Glyphosate and aquatic Imazapyr in areas that have standing water. The Aquatic formulations of these products are the ONLY products that can be lawfully sprayed. There is a good reason for this law. All other products have documented proof of harming Amphibians. Also, technically, you need to use an aquatic surfactant also. Aqua Gene and Aqua King are two brands. Studies have proven that other surfactants, and the built in surfactants and carriers contained in Roundup, Poast, Intensity, etc. can be more detrimental to Amphibians than the herbicide Chemical itself! As my photos reveal, my mix will brown down the RCG. I don’t care if it’s brown for a whole year! You have to kill the RCG, not tease it! Careful application does not cause damage to close growing natives as my photos also reveal. The key is careful, deliberate spraying, not blasting, misting or fan spraying. It’s really not that complicated. I will talk about the “upland” grass specific herbicides in a future post. My post here is intended to illustrate techniques to kill and eradicate RCG in high quality areas with standing water.
In my experience, the residual on imazapyr (Habitat) herbicide can last a very long time, from 1-3 years, depending on the amount of herbicide sprayed. Its residual means that the chemical’s activity in the soil will kill anything in the seed bank that germinates during that time. This can greatly deplete any native seed bank that may be available to recolonize the area. At my sites, what recolonizes after the imazapyr dead zones dissipate is more reed canary grease seedlings. We have switched to using imazapyr in wick applications only, not spraying it due to the harsh residual. But, I commend you on your very careful application style. I would like to know how your site’s spray zones fill in during the next few years.
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Have you ever seen negative effects of residual imazapyr in the soil? I have read that imazapyr is residual in the soil for up to 10 years.
Have you treated RCG like this with only glyphosate? What makes the addition of imazapyr beneficial?
Hi, Imazapyr will leave an area browned down for a year. That doesn’t matter to me. The objective is to kill the RCG. I have seen Ironweed prosper almost immediately after a burn down application. Glyphosate and all the other grass specific herbicides do not eradicate RCG to the level that I desire. In very nice areas I have hand sprayed my solution onto a cotton glove that I wear over a nitrile glove, and hand swipe the grass blades together in a handful bunch. I do this before any seed ripens. You have to try aggressive methods. If you are continually treating the same areas over and over, year after year, you are only damaging or eliminating desirable vegetation. Go for the strong chemo once and be done with it, for the most part. Ecological Restoration is not for the faint of heart.
Have you tried using foaming herbicide produced by Green Shoots? One of their customers gave a positive review regarding using their products to control reed canary grass.
Their foam is a plant extract (sugar and fatty alcohol). I have had good success handwicking their foam with the recommended four perecent active ingredient amount of glyphosate onto crownvetch. I like how foam does not run off the plant as would occur if a liquid was applied. This is the best method I’ve found for minimizing off target damage when applying glyphosate.
Applying this herbicide to only a few inches of the stems up from the base has been successful for me. I have taken Mr. Kleiman’s advice for basal bark application and applied it to handwicking. Mr. Kleiman previously wrote, ” In nice ares tighten up your application method.”