Today’s column finishes a two-part story regarding Roundup Ready technology and the unintended consequences of long-term vs. short-term thinking. Remember Roundup Ready soybeans crushed the DuPont STS competition. 

With the success of soybeans, Roundup Ready corn soon followed and grew in acreage as did cotton, canola, alfalfa, and sugar beets. This initially worked well, saved farmers money on herbicides and allowed for decreased tillage. During this time other herbicide chemistries and seed technologies were being developed but except in wheat and later sorghum, crops without Roundup Ready technology, had a hard time finding a market. Than what was a concern with weed scientists as discussed last week, weed resistance to glyphosate, started to rear its head.

At first there were just some reports that higher rates were needed or weeds were taking longer to die, and so on. The weed scientists started taking a look and through lab tests tried to determine what was going on, especially with pigweed. K-State weed scientists applied rates many times the labelled rate under controlled settings and found the pigweed wouldn’t die. 

Similar findings arose across the country. There were other factors in declining weed control such as improper application and low rates but the number of glyphosate resistant weeds was increasing rapidly. An international survey of glyphosate herbicide resist weeds indicates over 270 species as of 2016. The short term benefit, just as many weed scientists had warned was gone. What were the results?

• Minimizing or eliminating tillage for weed control became more difficult and many who had eliminated tillage started using tillage for weed control again.

• More expensive herbicides were available and their use increased. But in many cases, there weren’t good alternatives available or the control was incomplete.

• Producers are having to make more trips over the field to control problem weeds with different herbicides, tillage or a combination of both.

• Remember those STS soybeans DuPont developed that were outcompeted by Monsanto’s technology. They made a comeback and were even combined with the Roundup Ready technology. 

• Weed control of problem weeds has become more problematic and where these resistant weeds are present, decreased crop yield and quality. In certain cases, crop sequences have to be changed to deal with resistant weeds or extended fallow periods are used for weed control. 

• Manufacturers of many older herbicides, including pre-emergent herbicides are seeing an increase in sales. Many of these while effective, are much more expensive. 

 •New technologies such as dicamba and 2, 4-D tolerant soybeans were developed for broadleaf control in soybeans.

This doesn’t mean glyphosate (Roundup) is still a valuable tool or the issue can’t be addressed but it will require added expenses, time, and increased management. The frustrating part for all concerned was that issue could have been avoided and we knew how. Next week’s column will discuss dicamba tolerant soybeans and the challenge they present.

Dr. Victor L. Martin is the agriculture instructor/coordinator for Barton Community College. He can be reached at 620-792-9207, ext. 207.