Multiple sprayings for resistant weeds?

[catscratch]

I have some horseweed or marestail started in my plots and pastures. Burndown with gly got most of it but about 20% of them woke back up and are doing fine now.

They are past the rosette stage and bolting. I want them dead before setting seed. I know spraying once won't kill them, but what if I sprayed once a week for a while? Will it eventually be to much for them? What about alternating between gly and 24d each week?

I found lots of info online about control but nothing mentioned multiple regular sprayings, I'm assuming because it would be cost prohibitive for a farmer to do. I think I may only plant wheat this winters so that I can spray rosettes with 24d and not have to worry about plotted broadleafs. Even with this plan I don't want an extra crop of seeds this yr.

 

[Native Hunter]

I can't answer the question about multiple sprayings, but if you can watch them and mow about a week or two before the seed become viable, that will be the end of them. They can't recover and produce new seed in time before the end of the year, and they have put nearly all of their energy into seed production at this point in time. They are annuals, so their continued presence depends on seed production.

If you mow too early, they can still manage to flower again and do so on a low stalk.

This method does work with MT, but the timing has to be right, and it doesn't take care of the seed that are already in the seedbank. It also doesn't stop seed from blowing in from somewhere else, so you still may have some future issues. With one plant being able to produce a quarter of a million seed, MT can be a booger in a lot of places.

Best wishes.

 

[catscratch]

Thanks Naive. I can mow at any given time so I'll certainly try that with this yrs crop (that survives my sprayings).
Give me a hint as how to tell when it's almost viable. What do I look for? Timeframe after bloom?

 

[bigbluetruck]

Here, horseweed and marestail are the same plant. 2-4D will smoke marestail, if you can add some banvil or callisto that will help

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[THE LLC]

The only issue with multiple sprayings, from my understanding, is it may help develop resistant weeds.

 

[bigbluetruck]

If you mix a strong rate of 2-4D (4oz/gal) and spot spray they will die. If you do it now, there shouldn't be any residual to worry about

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[Native Hunter]

Thanks Naive. I can mow at any given time so I'll certainly try that with this yrs crop (that survives my sprayings).
Give me a hint as how to tell when it's almost viable. What do I look for? Timeframe after bloom?

Well.... it's kind of hard to describe. Like Justice Marshall said about pornography - I know it when I see it.

You know what the seed heads look like when the fuzz starts flying - so watch it and don't let it get anywhere near that point. As best I recall you will see the head close to formed but still green looking.

That's about as close as I can describe it.

 

[catscratch]

If you mix a strong rate of 2-4D (4oz/gal) and spot spray they will die. If you do it now, there shouldn't be any residual to worry about

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Dang, that is strong. I've already sprayed today, whatever is still alive in a week will get the 4oz/gal treatment.

 

[catscratch]

Well.... it's kind of hard to describe. Like Justice Marshall said about pornography - I know it when I see it.

You know what the seed heads look like when the fuzz starts flying - so watch it and don't let it get anywhere near that point. As best I recall you will see the head close to formed but still green looking.

That's about as close as I can describe it.

Will shortly after blooming work, or should I be more patient? I've been pulling them by hand and while that is effective, I think I really want something else to work better...

 

[bigbluetruck]

You might can use a 3oz rate but for as cheap as 2-4d is Id go with the 4oz rate, unless youre covering the whole field and are worried about residual for fall planting. I don't mess around lol, Id rather use a bit more and make sure everything is dead.
Situations like you described is one reason how we got resistant weeds, by not killing those you started them on the path to resistance.

I wouldnt mow them, just spray them, and do it asap, even if you just sprayed them again with Rup, the 2-4d will also help make the gly work better. That's why if I'm spraying Rup and there are any broadleaves in it, it gets 2-4d, it's cheap and it works.
Make sure you use 2-4d amine or wait until it cools off in the evening and wouldn't hurt to throw some surfactant in, Dawn dish soap works pretty well.

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[Native Hunter]

Will shortly after blooming work, or should I be more patient? I've been pulling them by hand and while that is effective, I think I really want something else to work better...

I think you would be okay once the seed head just starts to form. Especially if you mowed fairly close when it is hot. I hope it works for you, and I can also see why you might just want to continue the spraying. I hate those things too. Good luck.

 

[dogghr]

Def mowing will control it if you can do that. My guess is you have some resistant horsetail so should mix Gly with your 2,4 D in resistant plot. You can also use First Rate in that mixture for a good kick. Should wait 7 days or so before new planting. May want to ck specifics on that delay, going by memory.

 

[X-farmerdan]

Since you will be spot spraying (I assume?), it's not an issue, but there are limits on how much herbicide you want to apply to an area in any given year. You'll find that information on the herbicide label.

 

[bigbluetruck]

Here's some marestail that I sprayed with the 4oz/gal rate about a week ago.

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[buckdeer1]

That stuff is along ways from being dead,the problem is that the only stuff that kills it kills everything unless you use liberty link crops

 

[bigbluetruck]

It's on it's way out, just takes a little while, marestsil is tough stuff.

Ya but for the OPs situation a spot spray of 2-4D is his best bet

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[catscratch]

I'll read the label to find some of the specifics I need to know.

I have a bunch that is wilted like that. The problem has been that after a couple of weeks 20% of it pops back up fresh as a daisy.

I'm curious about the Liberty herbicide. I want to try spot spraying with a gallon or two of it. Lots of Pigweed nearby too. I certainly don't want to get that started...

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[buckdeer1]

I have had some like that I sprayed 2 weeks ago and it was still green and only alittle bit was still curled over.I hope yours is dead but in my area it would be just resting

 

[dogghr]

You could also add AMS to your gly or 2.4D to help with kill . Pretty cheap stuff. I still think combo will work better for you especially if you are spot spraying.

 

[catscratch]

Two days after 24d.

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