tennhunter

How long after applying Roundup can you mow without diminishing its effectiveness?

A large part of the surface area of the weeds that were sprayed will be mowed down a couple of days after spraying.

I realize it will take several days before the weeds are completely dead, but in two days will the herbicide be fully absorbed in the plant area which did not come in contact with the spray?

Thanks in advances for your responses.

hossdaniels

Depends on lots of things, mostly the tenderness of the weeds and the rate you used. Soft fast growing stuff may be fine. I think two weeks is recommended before disking, not sure about mowing. I would wait at least 5-7 days if I had ideal conditions(good soil moisture and reasonably warm).

Why would mow something you have sprayed with roundup?

Seed will probably come up better with the weeds standing, better soil contact, and it will have some mulch in a couple weeks.

haystack

Hoss has pretty much covered it. If you wanted a more rapid kill then adding 2,4,D to the mix would hasten the process, but then you would have to thoroughly disk/till the soil because of the residual from the 2,4,D. If Rye is what you're planting, then sowing right after you spray would work, Glyphosate/Round-up will not affect seeds and no tilling/disking would be necessary. If the vegetation is very tall and thick, then waiting two weeks might be needed before mowing or tilling. No need to worry if rye is what you're planting, it grows very fast(will sprout in 4 days) and frost and soil temp has little effect on seedlings.

On a side note, I see an advertisement for Glyphosate in this thread..."as low as $9.25 a gallon" I paid $47.50 a gallon back in the spring.

M.Magis

I have to question what you mean here. I'm not aware of 2,4,D making any difference in how fast the plants die. I do mix the two, but only to get a more complete kill on some broadleaf plants that gly can't quite control.
Adding AMS to the gly mixture can help, as well as adding a non ionic surfactant (even in gly that already has surfactant added). Either way I personlly wouldn't mow before one week, preferably three.
I've also seen gly prices drop dramatically recently. Glad I bought 2.5 gallons at the bargain price of $90.

haystack

Well, you've got me there Magis. I should have said a more rapid burn down, which will occur if using 2,4,D. As far as the whole plant(root) dieing faster, then no, that's not correct.

I'm assuming Tennhunter is planting a Rye plot due to a earlier thread where tilling in nitrogen was also discussed. If this is the case and no perennial seeds is in the mix, then IMHO, I would skip the spraying and waiting process altogether.

Instead, I would mow, till, spread the N, till again and sow the Rye right before rain. Either way, the rye will need to be killed next spring (using various methods) and you'd have plenty of time to kill the perennial weeds/grass then.

There's simply not many weeds or grass going to be able to compete with the rye going into fall/winter. And I would rather have a plot ready in about 2 to 3 weeks from now, so the deer harvesting could get under way sooner.

M.Magis

I thought that was the case, but I wanted to ask. I have seen people make claim that adding 2,4,D will kill faster, but I've sure never seen any proof.

haystack

Magis, In all honesty, I believe the question of whether 2, 4, D will kill faster than Gly is somewhat of a loaded question. IMO, it comes down to weed specifics such as type, size and resistance to gly both natural and man made.

Here's an example: Do I believe 2,4, D will kill Pennsylvania Smartweed or Wild Buckwheat faster than Gly, in my experience it sure will.

There are many other weeds becoming resistant to Gly also, including certain types of Pigweed, Lambsquarter and others that 2,4 D will easily kill.

M.Magis

I agree completely, and that’s why I like to use both when I want a complete kill. I’ve seen it implied that adding the 2,4,D to gly will speed up the effect on all grasses and broadleaf plants. I can’t buy into that, and I’ve never seen it happen.

ZACHLASS

adding ammonium sulfate will also make the mixture a lot hotter, when we farm we add it to the mixture we spray under orange trees and get a complete kill in about 7-10 days

hossdaniels

True, or up the rate or add more surfactant.