clearcast concentration for giant reed
We have a creekbed on our property in Travis county and the giant reed, arrundo donax is getting out of the banks.
We want to use clearcast to hold it back. Can you recommend a concentration for best use?
Travis County Texas
The label is the law and so you must use the labelled rates. Clearcast is labelled for use on Giant Reed at 64 to 128 fluid ounces per acre. Because giant reed is very susceptible to imazamox (the active ingredient in clearcast) treatment is often successful at the mid to low labelled rate for this species. In my experience, effective kill can generally be realized at 80 to 100 fluid ounces per acre, but this should not be taken as a guarantee or standard because your situation/application method/surfactant/etc. may differ significantly from my past experiences. I suggest you treat a small area first to determine the rate you need in your situation. Also keep in mind that imazamox will not be most effective until the spring when temperatures rise because many of the plants are dormant and not actively growing this time of year.
Thanks very much!!!!
Also, one more question. I looked at the Parks and Wildlife creek recovery project and they use 1% Clearcast mixed with .5% glyphosate. They also wait til summer / fall timeframe.
The lower concentration of Clearcast with the addition of glyphosate may be a cost cutting measure, as glyphosate is cheaper per acre than imazamox. Both herbicides are effective on giant reed, but I could not find anything in the scientific literature where the use of this combination of herbicides was tested for controlling the species in question. The effective herbicides for giant reed control are glyphosate (Good), triclopyr (Good), imazamox (Good), and imazapyr (Excellent). You can treat giant reed anytime during the growing season. Fall is often the best time to treat emergent vegetation such a giant reed because it hurts the plant during a time period when it is storing the most supplies to survive the winter. I only cautioned you not to treat until the temperatures warmed in the spring so the plants would not be dormant when you treat. I did not mean to indicate that spring was the best time.