I remember in my younger days looking forward to Saturday morning so I could watch “This Week in Baseball” with Mel Allen.  One of the features of the program was a film clip called “You Make the Call.”  This was a close or unusual play and the viewer had to guess if the batter was safe or out.  What follows is the equivalent of a film clip on what’s been done with Roundup Ready alfalfa to date (there’s still more to do).  As to whether or not it’s worth the added investment, well............. you make the call. 

First, here’s what we definitely know about RR alfalfa:

·       Exceptional weed control without crop injury

·       Convenient weed control for the life of the stand.

·       Currently a limited number of varieties

·       ~5-10% of seeds will be glyphosate susceptible

·       Tech fee is $125 per 50 lb. bag ($2.50 / lb. seed) 

Here’s what we need to know:

·     Will we get more yield, and if so, why?  genetics?, herbicide tolerance?, improved weed control?

·     Will forage quality be improved?

·     Will stand life be extended? 

Seeding year yield

        Even before RR alfalfa hit the market, Jerry Doll, UW-Extension Weed Management Specialist, established a field trial to look at the RR alfalfa system versus conventional establishment methods.  He found no significant difference in total season yield between the two systems, but virtually the entire yield from the RR system was alfalfa and at least some of the yield from the conventional system was weeds.  

        Beginning in 2006, UW alfalfa variety performance trials will include a comparison of RR varieties managed both with glyphosate and conventional (Pursuit) weed control systems.  The data for 2006 is presented below: 

         From the Wisconsin data, it’s clear to see that yield loss from herbicide crop injury/stress occurred, especially at Lancaster.  Will this carryover into year 2?  We’ll know by this time next year.  In Iowa State University trials, a similar scenario occurred with an average 0.3 ton per acre advantage across six RR varieties managed with glyphosate versus the same varieties where Raptor was applied.  At Southern Illinois University, researchers compared several weed management strategies with a single RR variety and found no significant yield difference in the seeding year, but noted better overall weed control with the RR system. 

        Of course comparing yields in weed control systems is only part of the story.  There is also the need to compare how these RR varieties performed in the larger conventional variety performance trials.  In most cases, they averaged about middle of the pack performance.  HOWEVER, we only have one seeding year’s worth of data, which is far short of what is needed to really measure their overall yield potential compared to other top conventional varieties. 

Recapturing the tech fee

        Can the $125 tech fee be recaptured in the seeding year?  Many factors come into play.  The seed cost is similar to slightly higher with RR varieties compared to the top conventional varieties.  Herbicide costs will be about $10 per acre less for the RR system.  It really comes down to how much, if any, yield is lost to crop injury (assuming good weed control in both systems with no forage quality differences) and if the selected RR variety is at least as good as a top standard variety (not all will be).  Below are results from a spreadsheet program comparing one scenario with a 0.2 ton per acre reduction from crop injury: 

            From this analysis, it’s clear to see that seed industry economists have done a good job of positioning the product.  Cost/return wise, it’s about a wash (with these parameters).  The benefit, if any, from years after seeding is yet to be determined but will be important.  Is the convenience of the RR system worth it?  You make the call.