How do farmers keep grass out of field?

[BobReeves]

last fall I plowed under an acre of grass, this spring I tilled, sprayed twice with roundup and tilled it before planting sunflowers. Sunflowers did well but now all dead. Just mowed everything down and the durn grass was at least a foot tall. It looks just like it did before I plowed it under last fall.

How the heck do farmers keep a field from returning to grass?

My plan is to till it which should grind up what stalks the mower didn't crunch but that will only slow down the grass growth. Do I need to spray it 3 or 4 times a year or what.

 

[Mark W.]

If you tilled it after spraying you exposed fresh soil that didn't contain the roundup. Fresh bed for new seeds to land on and grow.

 

[rrlund]

What kind of grass is it?

 

[2002sliverado]

I would suspect you have quite a "seed bank" in that acre which had been grass for a lengthy period of time. You are probably in need of some sort of post emergence herbicide to continue to control the grass. You may even need a soil applied residual herbicide. I am not familiar with the herbicides labeled for use in sunflowers. I have been around corn, soybeans, and alfalfa primarily. Those herbicides labeled for use in sunflowers is something you should be able to find out from a local retail agronomy center.

 

[Fordfarmer]

Roundup needs to be sprayed on growing plants...it does not work if sprayed on the soil.

 

[coshoo]

Generally best to spray Roundup (and wait a couple weeks for the kill to be complete) before plowing. Then let it grow up to weeds and grass, and spray again. Roundup only works on growing plants, not on
dirt- after 2 days or so, plants will grow right back as though you had never sprayed.

 

[David G]

The advise is spot on, apply the herbicide, wait a few weeks, then plow, otherwise might as well pi$$ on it.

 

[jeffcat]

I like the "seed bank" reply. Got a good chuckle. That is quite a
problem that is for real. Every time you are plowing up the history of
that land and it can go back more than a century. That is why there is
no till. Leave all of that stuff under ground. You can be fighting a
very long winded losing battle.

 

[tomNE]

with all the grass seed in the soil, every time u till it, it replants the seeds. you may not like the explaination but it's true. If u feel u must till,
i'd do it in the fall and let all the grass germinate and spray it in the spring. depending on what you plant, you can probably add a chemical to the roundup,
(we use 'dual') this will give you some residual. planting sunflowers is usually later in the growing season; you can keep spraying roundup after each flush
of new grass. I'm afraid tillage will never eliminate your grass problem!

 

[Bruce from Can.]

I don't know a thing about growing sunflowers, but with round up ready corn , we always add some kind of residual herbicide . Round up kills
the weeds that are there the day it is sprayed , and the residual kills the weeds that germinate later. Some use some Atrizine with the
Roumdup.

 

[BobReeves]

Pretty close to what I did this spring.. Sprayed the acre when the grass was growing back from the fall plowing. Waited till it died then tilled it. We had rain and by the time it was dry enough to plant I had another grass crop. Sprayed it waited till it died, tilled it to break up the clumps and then was able to get the sunflowers planted.

Grass is a mixture of Oklahoma prairie grasses with weeds for good measure. This place has probably been grass for as long as humans have inhabited the earth.

 

[BarnyardEngineering]

Sounds like you were plowing/tilling THEN spraying roundup?

Wrong order. You need to spray the plants, wait at least 3 days, THEN plow it under.

Roundup is drawn in through the leaves, and propagates to the roots.

Some grasses are also resistant to roundup. There is some sort of brome grass that's taking over our farm that Roundup burns back, but won't kill. Plow it under for 3 years, and as soon as you put the ground back into grass, the brome pops right back up. Thick and heavy, but it grows out to stems and goes to seed before anything else is big enough to mow.

 

[BobReeves]

If I don't till to break up the grass clumps it's almost impossible to plant. This grass has root clumps like soccer balls and if they are not pulverized or plowed under a planter doesn't stand a chance of working properly.

 

[David G]

I do not think 3 days is enough, I would wait 2-3 weeks.

 

[BobReeves]

So should spray first then plow it under again this fall?

 

[WGM]

Three days is more than enough time provided you use concentrated Roundup farm supply stores and coops sell. If you use the watered down stuff home improvement stores sell, then 2 to 3 weeks would be required.

 

[Janicholson]

After waiting for at least a week between application and tillage. Jim

 

[coonie minnie]

Kill it this fall, and then leave it. Plowing it is only establishing new seeds, and spreading ryzomes that might still be alive.

 

[Tim(nj)]

Depending on what you are using to plant with, you can try the stale seedbed method. Plow, then work the ground early in the spring and leave it for a while. Right before you plant, spray anything that came up with glyphosate and then next day plant your sunflowers without doing any additional tillage.