Glyphosate (roundup and many others) has been an excellent herbicide for many years, controlling many weed species. The roundup trait was introduced into soybean almost 10 years ago, and has made dramatic inroads as probably 90% of the soybean crop planted in our area is roundup ready.

Corn acres are showing impressive acreages devoted to the roundup ready gene as well. Nation wide, approximately 50% of corn acreage is devoted to roundup ready corn. What concern, if any, does this represent to the future of this excellent weed control product?

The past few years we have seen an increase in the amount of glyphosate required to provide acceptable control of some weeds. Does this mean some weeds are becoming tolerant or even resistant to glyphosate? This may or may not be occurring locally, but across the Midwest there are more and more weeds that are becoming resistant or tolerant to this product.

Marestail was the first weed that many of you could easily identify, that became resistant to glyphosate. Resistant marestail was first found in states east of Illinois, but now has been confirmed in Illinois as well.

Populations of palmer amaranth, a close relative to waterhemp, was found in Georgia and Tennesee to be "tolerant" of glyphosate. Several populations of common waterhemp in Missouri are also being treated as "potentially resistant" to glyphosate. All these populations are being tested for confirmation of possible resistance.

A population of common ragweed in Missouri has been confirmed to be resistant to glyphosate. A common ragweed population in Arkansas has been labeled resistant. A population of common lambsquarter is being investigated as "tolerant"

How many more examples do we need before we begin to treat this herbicide with the respect due it to allow its use to continue into the long term future? Many of you may remember when roundup ready soybean first came out and the question was being asked about the potential for resistance to develop. We were told not to worry, that this herbicide requires plants to undergo several mechanisms to acquire resistance. And since most herbicides require plants to undergo only one mechanism, resistance was very unlikely. Unfortunately, if you give plants enough opportunity, they will adapt. And this is what is happening now.

We can't continually apply a product (it doesn't matter which one) and not expect mother nature to adapt. To be brutally honest, if we want to be able to utilize this product in the future, we better start taking steps now to prevent resistance from developing.

We can do this by using glyphosate in a responsible manner. This would include using the correct rates to kill the weed the first time; utilizing herbicides with differing modes of action (use different chemistries); not relying upon a single mode of action for your herbicide program; use sequential applications; rotate crops; tank mix products, etc.

As yourself this question, if you are growing roundup ready crops each year in the same field, how are you going to limit the possibilities of resistance? You must remember, every time you use a product, you're selecting for resistance. And the more times you use it the more likely you are to see resistance occur. What are your plans for control of waterhemp (and other weeds) if glyphosate is no longer effective?