# Roundup Ready Alfalfa spraying



## barnrope (Mar 22, 2010)

I have a field of RR alfalfa. Planted the first time in Aug of 13' and the second time about May 5th. The portion that retained good snow cover last winter is now between knee and waist high and just starting to bloom. When I replanted, I went through most of the entire field. The rest is about 6 inches tall. I know you are supposed to spray it about 3 weeks after planting, but I haven't yet. My seed dealer/ chemical guy wants me to spray right now. I am wondering if I should wait until after I cut the field, or if I should take his advice. I just hate to run down any of the good stuff.

With a 100' boom on a RoGator it won't be a lot but there will be some tracks out there. Any ideas out there??? Thanks!

This was the good part prior to replanting...



And this was the poor part....


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## vhaby (Dec 30, 2009)

barnrope said:


> "I have a field of RR alfalfa. Planted the first time in Aug of 13' and the second time about May 5th. The portion that retained good snow cover last winter is now between knee and waist high and just starting to bloom. When I replanted, I went through most of the entire field. The rest is about 6 inches tall. I know you are supposed to spray it about 3 weeks after planting, but I haven't yet. My seed dealer/ chemical guy wants me to spray right now. I am wondering if I should wait until after I cut the field, or if I should take his advice. I just hate to run down any of the good stuff.
> 
> With a 100' boom on a RoGator it won't be a lot but there will be some tracks out there. Any ideas out there??? Thanks!"


That's a tough question. I wouldn't be concerned about RoGator tracks if you don't plan on cutting the alfalfa in the next week or so. The tire-track alfalfa may not stand back up, but modern cutters will effectively cut the down hay. The need to spray now is to eliminate the non-Roundup Ready plants.

From The 2014 Technology Use Guide Addendum:

"Due to the genetic diversity of alfalfa, up to 10% of the seedlings are susceptible and will not survive the first application of Roundup herbicides. The initial application is necessary to eliminate the effects of stand gaps created by loss of plants that are not Roundup Ready and to ensure adequate spray coverage of emerging weeds before crop canopy interference."

So, spraying the fall-planted seedlings now will kill up to 10% (the non-Roundup Ready alfalfa plants) and leave the field with hay containing dead stems (yes, all stems in alfalfa hay are dead anyway.) The problem with spraying the early seeded alfalfa now is that any germinated weeds will be shielded by the alfalfa canopy. Delaying spraying now will allow any germinated weeds in the late seeded alfalfa to grow and be more difficult to control after the first cutting. So, read your technology agreement to determine the spraying requirements/ timing. If there are no instructions for what to do in your current situation, spray now using the first 22 oz/ac Glyphosate rate and evaluate the weed situation after the first cutting to determine if the field will need spraying a second time with 22 oz Glyphosate per acre to control germinated weeds not controlled by the first application of Glyphosate.

Hope you obtain a good stand of alfalfa!


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## Vol (Jul 5, 2009)

Yes, I also would probably not worry about the tracking to be sure and get a good coverage/kill on the weeds. You probably will not have very many of the non-RR seedlings/plants as when I sprayed my RR for the first time it appeared as if the dead alfalfa plants were very few and very far between....actually quite difficult to find. I love my RR alfalfa and if it were not for RR alfalfa, I would not attempt to grow it here with our large annual rainfall.

Regards, Mike


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## SVFHAY (Dec 5, 2008)

I wouldn't worry about what's run down IF you have weed pressure. I haven't seen enough kill of alfalfa when I spray rr to think that is a consideration"here:. Maybe it is just this lot of seed.

Mike, what do you mean when you say you wouldn't attempt non resistant alfalfa because of plentiful rainfall?


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## Vol (Jul 5, 2009)

SVFHAY said:


> .Mike, what do you mean when you say you wouldn't attempt non resistant alfalfa because of plentiful rainfall?


Weed/grass pressure.....it is so fierce here due to the high temps, high humidity, abundant rainfall and lengthy growing season. Gly is cheap compared to alot of the chemicals out there.

Regards, Mike


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