E-word in NYT -- a bigger surprise than Roundup-ready weeds?
There have been isolated reports, for years, of various weeds evolving resistance to glyphosate (sold commercially as Roundup etc.), but now glyphosate-resistance is showing up in pigweed, a major problem for farmers in the US and elsewhere. Among alternative ways to kill weeds, other herbicides are mostly more toxic and break down more slowly, whereas mechanical cultivation tends to increase erosion.
On the positive side, maybe more people will buy my book on Darwinian Agriculture, although I'll have to revise it before publication to turn what was a prediction into a fact. Maybe I can get some
Neanderthal crackpot with a radio show to accuse me of deliberately spreading Roundup-resistant weeds to increase sales. You can't buy publicity like that! But I'd rather have clean rivers than a best-selling book.
I was impressed that many of the experts discussing the problem in the New York Times referred to "evolution" or "natural selection", although one referred to weeds as "opponents that can adjust" (as if individual plants were trying different ways to survive herbicides) and said that some weeds can "mutate to survive", as if mutation were somehow directed. Plants have evolved so that individuals can adjust to certain changes in their environment (drying soil, for example). But it's populations, not individuals, that evolve. And, in this case, they evolved mainly because herbicide-susceptible individuals did not survive. I assume the author knows this, but some readers could be misled.
Maybe now people will start paying more attention to management practices that slow the evolution of herbicide resistance. Resistance-management programs for insect pests, to slow the evolution of resistance to the Bt toxin, seem to be working reasonably well, but there's nothing similar in place for weeds yet.
One important difference is that the insects plaguing an individual farmer may well come from a distant neighbor, so there's little individual incentive to implement expensive resistance-management programs. An individual farmer's weed problems, on the other hand, are much more dependent on how they were managed on that same farm in the past. So farmers may be more motivated to invent and implement resistance-management strategies for weeds.
One of my favorite weed management strategies is alternating, every few years, between using a field for grazed pasture, where weeds of row crops tend to die out, in rotation with row crops, where pasture weeds tend to die out. That requires farmers with the expertise and willingness to work with both crops and livestock, however. And milk or meat from animals eating mostly grass and clover may be more expensive than the same products produced in a feedlot.