# Who has to usually spray for alfalfa weevils?



## FarmerCline (Oct 12, 2011)

Just was wondering who usually has to spray for alfalfa weevils every year and when? There is pretty much no alfalfa grown around here but my extension agent told me that I would most likely have to spray for the weevils before 1st cutting in the spring but after that they wouldn't be an issue. In mid April I saw some damage from the weevil larvae but not enough that I felt it was worth driving over knee deep alfalfa to spray. I'm wondering if I just got lucky that I didn't have to spray. My alfalfa is just now getting ready to start to bloom and am looking to cut when I get the weather.


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## PackMan2170 (Oct 6, 2014)

I have to spray like 75%+ of my acreage every year . They can be pretty voracious and seem to be getting worse all the time, especially because all the people with <10ac won't spray. If they get bad, don't opt to not spray and cut instead because they can kill your regrowth and will effect your stand. They only require spraying before 1st cut, but they are truly a pain in the @ss.


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## Teslan (Aug 20, 2011)

Just did 2 weeks ago. Have to every spring. Once in awhile before 2nd cutting. I don't know how anyone can grow alfalfa without spraying for weevils and aphids.


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## Vol (Jul 5, 2009)

Those weevils will build up in your field over time(egg laying cycles).....one of the best preventive maintenance things you can do is spraying in the fall(kills adults) and then early spring....weevils are early insects. If you don't spray they will eventually build up in your field and then you WILL spray. Haybaler 101 passed the fall tip onto me a couple of years ago....and suggested that I use Lambda Cy insecticide.....it works well.

Regards, Mike


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## aawhite (Jan 16, 2012)

Anyone leave sacrificial strips? We tried this a few years ago. Leave 2 or 3 uncut strips in the field, as the mowers work the weevils mov into those check strips. Then spray just the strips. I thought it worked okay, definitely saved on chemical cost, but we eventually quit doing it. I think Dad didn't like the sight of uncut hay being devoured.


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## vhaby (Dec 30, 2009)

Weevils are like "death and taxes." Had to spray the seedling year, but, even though they were universally on the alfalfa this year, the concentration was sufficiently light that I held off spraying and took them out by cutting. Regrowth is not affected by weevil. Next year...??? Here, aphids are fairly well biologically controlled by Lady Beetle.


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## haybaler101 (Nov 30, 2008)

Yeah, I am spraying after 1st, 2nd, and 3rd cutting for leafhoppers. I think this gets the adults the year before. Almost never spray established alfalfa for weevils but almost always have to spray a new seeding planted in August the next spring.


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## mlappin (Jun 25, 2009)

Not a problem in our areas in most years, once in a great while we do have to spray for weevil. If you miss a spot or decide not to spray one field, you can definitely tell later in the year.


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## Teslan (Aug 20, 2011)

The problem with leaving sacrificial strips is that the weevils come before first cutting so if you don't spray you will have very little to cut to leave a strip. At least here that's how it is.


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## PackMan2170 (Oct 6, 2014)

Maybe your weevils aren't as tough as ours, vhaby, but I have seen them devastate regrowth. Especially if a person doesn't cut very short and leaves them any shade to hide in.

Best part is we never used to have them. They have only showed up in the past 15-20 years, and have made themselves quite at home.


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## Teslan (Aug 20, 2011)

PackMan2170 said:


> Maybe your weevils aren't as tough as ours, vhaby, but I have seen them devastate regrowth. Especially if a person doesn't cut very short and leaves them any shade to hide in.
> 
> Best part is we never used to have them. They have only showed up in the past 15-20 years, and have made themselves quite at home.


I agree. We've tried and tried to avoid spraying by cutting if they infest close to 1st cutting time. But it never fails we have to spray. Last year we had to spray twice because the 1st time the coop decided to use a different chemical for some reason. It failed. So we had the crop duster come. He never fails.


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## ozarkian (Dec 11, 2010)

I usually spray once before the first cutting. This year they were terrible. Sprayed twice. I think the cold winter just made them mad.


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## Hugh (Sep 23, 2013)

My question about the weevils: Do they prevent green-up after the first cut? I had a super green stand about 20" tall. I cut about 10 days ago, and now have a few weevils and the stand looks yellow in areas.


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## Vol (Jul 5, 2009)

Hugh said:


> and now have a few weevils and the stand looks yellow in areas.


Sounds like(yellow) Potato Leafhoppers....probably need to spray....Lambda Cy

Regards, Mike


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## vhaby (Dec 30, 2009)

Could also be three-cornered alfalfa hopper, but damage from this guy shows up as the plants get closer to maturity. The alfalfa hopper girdles the individual stems about 1/2 inch above soil level and lays its eggs in this girdled stem. Girdling prevents plant sap from moving up into the plant and these girdled stems turn yellow. To know for certain, do a series of sweeps with a net and send the caught insects to a university or other entomologist for identification.


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## rjmoses (Apr 4, 2010)

Hugh said:


> My question about the weevils: Do they prevent green-up after the first cut? I had a super green stand about 20" tall. I cut about 10 days ago, and now have a few weevils and the stand looks yellow in areas.


I agree with Mike. By this time of the year, it's probably leafhoppers. Had to spray here last week.

The biggest problem I see with insects is that there are no longer effective pesticides. Almost impossible to get anything around here except permetherin based sprays. And these are only contact sprays. No residual effects.

Ralph


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