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gil.gullickson
Veteran Contributor

Preemergence herbicides

All, 

Preemergence herbicides are always recommended at every weed control meeting I go to. That's from the perspective of getting the crop off to a good start and getting in some additional herbicide modes of action to forestall herbicide weed resistance.

 

I always wonder, though, how this plays in the real world, where you get cold and rainy weather in front of planting. Have you folks been able to make them work? Any activation concerns? Any benefits or drawbacks you're seeing?

 

Thanks,

GIl Gullickson

Crops Technology Editor

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8 Replies
Shaggy98
Senior Advisor

Re: Preemergence herbicides

I've always used a preemerge herbicide with residual control in front of all spring seeded crops. Depends on the in season moisture we receive, but we're in a dry enough climate that most years the residual control provides enough control until the crops are all canopied out and we don't need to come over the top with anything. Notice I said most years, not all years.  Every once and a while we get abnormal summertime moisture and we require some in season control.

 

This is the second year I've used residual control in front of winter wheat seeding and it looks like I won't be needing any in season application.  I don't know if it's the herbicides keeping the weeds back or if it's the lack of wintertime moisture.  We are still in the grasp of an on going drought.

 

FWIW, the wheat fields that were drilled later last fall and didn't receive any preplant herbicide are all covered with mustard weed this spring, so I'd be betting the herbicides are offering good benefits.

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Pat in CMO
Senior Contributor

Re: Preemergence herbicides

I have been using pre-emerge herbicides for years with very few problems. In my opinion the best way to control hard to kill weeds is never let them get out of the ground.  Patrick

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WCMO
Senior Advisor

Re: Preemergence herbicides

Chemical company reps, salesman, dealers, etc., are paid to teach the benefits of pre-emergence herbicides.  That's not to say there aren't benefits -- that's just to say it's possible that the teachings could be biased -- how much is real science, and how much is marketing -- how much is the real economic benefit, and how much is marketing.  My own dealer is recommending burn-down with pre-emergence treatment, plus later in-crop treatment.  Followed that practice annually until things got easy with RR technology.  Probably going back to it.

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ECIN
Senior Advisor

Re: Preemergence herbicides

I have always used a pre emerge here and for the most part , I think its a good program , But if you look at some of the problems today - If you are going to control weeds you need a pre - example - marestail , For this season I did a fall app. of weedmaster and powermax - this will get alot of them , but with the price and the period of time in the spring - I dropped any 2-4-D produces and use Sharpen at 1 oz rate - no  7days of month wait  then I will apply before the beans come up a 4 oz rate of Authority XL  , IF you don't control marestail right off the bat ,you can post anything that will kill them let alone keep them in check .

 

IF there is a problem , it will be that very small window to apply before the beans come up , I have seen beans break out in 3 days , then throw in a windy or 2 days then you can get behind . Last year a lot around here used Verdit , and got into that wind problem and they REALLY pushed the envolpe , REALLY pushed it , They did themselfs no favors as they smoked trees , gardens - you name it - Know of 2 around here that did that , That = some very unhappy neighbors , or as in one case , several neighbors .

 

I have fealt the same way about some dealers really pushing there agenda , but for the most part today , they are giving good advise to control early with the pre emerge .

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Mike M2692830
Senior Contributor

Re: Preemergence herbicides

Gil, I started split applying nitrogen where I put on NH3 in the fall and then have the coop apply the remainder in the spring with a pre. Will follow up with Halex at V4 to V8 along with a fungicide. I'm after no resistance with this program. Going with Flexstar GT on soybeans early post....MikeM
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Husker-J
Senior Contributor

Re: Preemergence herbicides

I used pre-emerge herbicide the last 5 years.

Guy across the fence, uses burn down (sometimes twice) followed by gly during the growing season (again, sometimes twice).

I only need the follow up gly about half the time, and my field is much cleaner than his, and yields are a 'little' better, not spectacularly better, but enough better to cover the extra expense of the pre-emerge.  
On top of that, the last year or two, he had a couple circles of weeds that 'wouldn't die'.   I don't seem to have that problem.

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buckfarmer
Senior Contributor

Re: Preemergence herbicides

Clean fields at harvest are worth a lot, even if the extra yield dosn't pay for the pre-emerge. Last year was the first year I used pre-emerge and couldn't believe how much easier Harvest was. I never had bad weeds but just enough to keep me from running on some days.
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Longcreekfarms
Senior Contributor

Re: Preemergence herbicides

I'm with Pat. Never let em get started. On a corn, wheat, bean rotation. Things stay pretty clean. Depending on weed pressure and variety, I apply different pre's.
Cleaner ground that's due to go into corn gets simazine/atrazine. Problem fields get Callisto products like lumax.
I use envive in beans. Canopy if I think there will be a volunteer corn problem. Side by side comparisons really show a difference here.
Wheat gets Peak put on in the fall and rarely need anything else on it but N in the spring.
I'm going more and more no-till all the time and parking the plow requires a pretty good understanding of weeds and chemicals. Timing is everything!
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