Everything you need is contained here:
See this also:
Of course, you know that it would be very difficult to say with 100% certainty that a herbicide resistant weed population came only as a result of LCO applications on a particular property. Herbicide resistant Conyza canadensis
and Amaranthus palmeri
have been found (and DNA fingerprinted) in fields in which herbicides have never been applied. Some of this can be random variation and some of it can be the result of seed or plant material travel.
But, when we see evidence of resistance in inner-city areas, where exposure to agriculture is limited, and only one mode of action has been used for many years, the problem becomes a little more clear.
So, what is your position? There is no doubt that we're seeing more herbicide resistant weeds. In some areas of the southeast, herbicide resistant spotted spurge has taken over 50%+ of the area of many lawns. This weed is resistant to both the older cheaper chemistries and the newer more expensive ones. Do you suggest that we keep using thesame old cheap materials until you have nothign to do but hand pull 50% of your treated acreage?
If resistance can be seen in a 20A farm field, why can't it be seen in thousands of LCO acres?