Reed Canarygrass is a coarse, cool season perennial grass that grows 2 – 6′ high. It has become a major threat to in ecological integrity of our native wetlands as it forms large, monotypic stands and outcompetes most native plants. Invasion often occurs in concert with disturbances, such as ditch excavation and stream modification.
This paper describes a reed canarygrass removal study at five sites in eastern South Dakota using imazapyr, imazapic, and glyphosate individually and in combination to determine which methods were most effective. Eight treatments (five in fall, two in spring, and a control) were applied at each location in fall 2005–spring 2006. Herbicides were applied over clipped vegetation that had residual vegetation removed. Reed canarygrass cover was 93% in untreated plots, and ranged from 21%–66% in herbicide treated plots at the conclusion of the study. Herbicide treatments containing imazapyr provided control for two growing seasons.
Further information can be found in this paper using the link below…
2014 (Bahm etal al) Evaluation of Herbicides for Control of Reed Canarygrass
6 Comments Add yours
I’ve never dealt with Reed Canarygrass, but we are seeing the same take home message in GA as far as our non-native invasive treatment strategy, as a whole – herbicide treatments can require substantial follow-up (just like when using fire for restoration.)
We initially assumed herbicides would be a one-time treatment, but we were quickly proven wrong. Some non-natives resprout, and some quickly reinvade via nearby seed sources, or both.
We have been treating one 10 acre bog using herbicides for the past 5 years for the invasive Miscanthus sinensis. We have made a lot of progress using an aquatically approved version of glyphosate at 2% solution. However, each year we find new sprouts – presumably from seed. I suspect we will be treating that bog for probably 10 more years.
We have to be realistic with the time it takes to reach our restoration goals. Many times, it ends up taking a lot longer than we anticipate (“one more burn and this site will be perfect.”)
Imazapyr is a heavy-hitter. I do believe it is soil active to some extent. It is great for the stubborn weeds, but can be hard on the nearby non-target vegetation. We only use that for the real tough ones, or if there is truly no non-target concerns. I prefer glyphosate imazapic and/or triclopyr when possible. They are lighter on the land. Most all herbicides now offer an aquatically approved version for wetland applications.
That’s my experience,
District Wildlife Biologist
Chatt-Oconee NF, Chattooga River RD
706-754-6221 ext 101
I would submit that the crucial lesson to take away from this article is a couple sentences in the discussion that indicates that, though the reed canarygrass was gone for two years, it returned to dominate in year 3, and that the native plants they planted to compete with it did not grow because they were upland species inappropriate for the site. The abstract reads like this project was a success because the exotic plant was killed for two years, but in fact it was a failure. Reed canarygrass again occupies the site, and most of the native plants that had managed to hold on against it are now dead from the herbicide. The result is the opposite of restoration. There is an obvious explanation, and it is a lesson in itself. It appears they undertook this project without an understanding of what they should be restoring in the site. In retrospect, they realized that they planted a seed mix that couldn’t grow in the site because it was for dry sites. But plants are adapted to more than “upland” or “wet”, and you really need to think about what should be growing in your site. “Native species” is not enough.
There is a second, less obvious explanation that also makes restoration difficult, and might have caused their project to fail even if they’d planted the right species. Most natural systems are dominated by conservative species – climax species or K-selected species that are adapted to hanging on and not so much adapted to moving into places. They tend to have fewer seeds, and they often need more exacting conditions to get established. It is worth trying to plant them, and if you have nothing left, it’s the only way to restore anything. But it is hard. The exotic species that are invasive are ruderal – weedy, prolific, adapted to getting their seeds around, and establishing easily in open space under many conditions. And if you succeed in keeping them out, there are native ruderal species that also may show up and take over. And that too is not a success, though it may be somewhat of an improvement. But it really emphasizes the importance of hanging onto whatever desired species you still have in your site. Any time you kill non-targets, you’re making your ultimate ecological goal disproportionately harder to achieve.
I would echo what Mike Brod said. Restoration calls for patience.
I’d like to chime in here about patience. Patience is absolutely required, but it’s not enough. Patience refers to being conservative “across time”, but we also need to be conservative “across space” (i.e. not biting off more than we can chew). Any kind of restoration has the potential to create more harm than good. When we lay bare a habitat, reduce its cover, and disrupt it (even if we are disrupting what we consider to be undesirable elements) we are taking a chance. As Mike pointed out, many of our desirable native species are K-selected or climax species and take a long time to establish and spread. We need to select a small enough restoration area so that we can protect the native elements during and throughout the restoration process, especially the rare or special elements.
To this end, we should never underestimate the value of hand labor applied surgically, as compared to a relatively indiscriminate systemic approach. If I had to suddenly restore 1000’s of acres I don’t know what I’d do. Fortunately with mountain bogs, they are usually quite small (Shady Valley notwithstanding) and a dedicated volunteer team can do wonders. I can’t stress enough the importance and value of developing a pool of dedicated and trained volunteer restorationists.
Wish I could have seen the shady valley stuff . Perhaps I am one of the embarrassed few on this list who have attempted control of this species here in NC in “mountain bog”. I (and others) introduced our effort in an obscure, and outdated published note (see attached, but only read if extremely bored since it says very little about the control efforts, and then, only the initial stages). We continued aggressive herbicide campaign for at least two years (maybe longer). We avoided edges with native veg and the rare, occasional native that poked through the Phalaris mat, etc, etc.
I actually believed we had eventually achieved control. We did no native plantings, expecting natives to magically re-appear (some did). You could actually see water in the wetland again! I personally abandoned the site for a year (and now even longer) or so thinking we were done., …the site had been completely overrun (again). Not sure if you all understand what overrun means…..it is essentially mono-specific. Not clear if the return was from seedbank or seed wash from overbank flooding (which we do get even though the site shouldn’t by subject to certain definitions)…
Anyway, at some point I’d be willing to embarrass myself further and illustrate what we did and why and what happened, complete with some interesting images. Better yet have you walk through it.
Take home messages –
direct experience is best.
The fight is never over
We need more help
this plant, at least on our site, is not like any other invasive in NC (maybe cogon will eventually be like this).
not sure what “general” lessons apply.
There is voluminous literature about this plant…is it helpful?
It’s easier to do nothing, and perhaps, less frustrating
I’ll stop there, but could go on…
Happy to hear what we “should’ve done”!
This is probably redundant, but having developed a good bit of experience in invasive control in (S. Appal.) forested areas and in a number of bogs, I emphatically agree with the earlier commenters. We learned, years ago (and even assumed when first starting) that you have to go back year after year to the same targeted area and retreat, as Mike Brod pointed out. We have found with most of the invasives we deal with, that it is possible to achieve 90% – 95% removal after 3-5 years treatment, depending upon the species and original infestation. This is a general statement about control; there are qualifiers that require more discussion than time/space allows here. But here are some important points:
1) If there is funding, it is ALWAYS important to conduct a good inventory throughout the property in which your potential target area will be. It almost always happens that there are more species, and they may have spread farther than you originally thought. A good inventory then lets you…
2) Develop a Management Plan which enables you to determine the target area size and how much time/effort/$ that need to be allocated for success . In this way, you address Mincy’s points. Breaking larger tracts into smaller project areas and prioritizing them, for example, can facilitate successful control.
3) It is important to consider ahead of time what happens after successful control treatment, i.e. ALL of Mike’s points about restoration. That information he adds about the subtleties of native ruderal and native conservative species regeneration is really insightful and important. (Thanks for adding that, Mike!) We have focused strongly on avoiding damage to existing natural vegetation (“First, do no harm.”), and have found that an amazing regeneration and repopulation of these plants usually follows treatment, so protecting them is extremely important. (Sometimes, another invasive that had been lying low will begin to colonize, but you deal with that one then.)
4) From the very beginning it is important to be fully aware that invasives management is ongoing. You can rid an area of 90% invasives, (or whatever your targeted level of success is), and your goal (or at least my goal) should be to leave the area controlled in a manageable condition for those oversee the area. Ideally, managers, volunteers, etc., can then perform maintenance every year, (two years, three years—whatever is needed) by walking through and pulling or otherwise treating sprouts, as they appear. This would be necessary even if 100% of invasives and their roots and banked seeds were ultimately eliminated (which is unlikely), because more seeds will be introduced through time from wind, water, and wildlife/humans. But this maintenance level can be accomplished on most sites. (Sites defined here as small acreages — low hundreds, not thousands.)
By the way, we have not even considered using Imazapyr because it can transfer in the soil to roots of other species which might extend into the target area and damage them. It might be okay in a highly altered area to be restored that is devoid of desired, existing native species, but I would be very careful.
Good discussion Adam; thanks for the report!
North Carolina is considered to be at the southern-most extent of RCG’s current range according to the USDA Plant Database, yet we discovered an initial infestation in Hale Ridge Bog during the BLN spring field tour. So, although RCG hadn’t been documented within the SABs where WNCA has managed NNIP over the years in Henderson Co. (Kanuga; Hyder Pasture; Ochlawaha) during the time of our work at those sites, its extensive presence in Bat Fork Bog is particularly concerning in terms of the potential for this invasive to establish within other WNC bog sites with similar natural communities and hydrology.
Further, it sounds from the article like the Bat Fork Bog community type may be more akin to McClure’s than to the Henderson Co. bogs mentioned above.
In any case, we’ll need to remain vigilant so that we can nip any initial RCG infestation in the bud before it has the opportunity to consume McClure’s as it has Shady Valley’s bogs and Bat Fork.