The Coalition was established to investigate treatments for kudzu that did not use chemicals. However, in 2007 we began participating in studies that involve herbicides to better understand how chemical and non-chemical methods are best used — possibly together. Coalition volunteers do not apply chemicals in these studies. One study takes place at two sites in Spartanburg, and another study takes place in Sumter National Forest.
There is a phenomenon observed by the Coalition when using herbicides: delayed emergence. Here is an explanation of this effect, provided to us by Bill Kline, a researcher in the Vegetation Management and Range & Pasture businesses of Dow AgroSciences in a December 2009 e-mail (used with permission).
… this is what I tell folks about perennial plant control in general with herbicides: "Sub lethal doses of herbicides applied to perennial plants generally delay emergence the following spring". And this is true with kudzu. Basically, observations taken early the following spring can appear to be providing control — i.e., no emergence. Later observations generally show simply delayed emergence and by the end of the growing season, treated plants can appear almost the same as untreated plants. Now remember that this is when sub lethal doses are applied — for whatever reason — too low of a rate, the wrong herbicide for the target plant, poor application, shielding from other foliage, etc. Of course when the correct herbicide is properly applied to a susceptible perennial plant then these responses do not occur because a lethal dose kills the plant.
The following additional links might interest individuals who want to know more about using herbicides to control kudzu.
The Forestry Division of the Tennessee Department of Agriculture provided us a detailed summary of herbicide use for kudzu control. The link is below. One caveat: It advises digging up kudzu roots for "spot treatment". This is completely unnecessary, as is desribed elsewhere on our website.
Herbicides: The Bottom Line