Lets talk about pre-emergent herbicides.

[Foggy47]

I'm going to drill some Northwoods Whitetails Sorghum in the next few weeks. Reading their info on planting says to use a pre-emergent (Simazine or Atrazine).......and I have never used one in the past. This will be less than 1/2 acre total in some strips in my plots in order to provide some vertical cover and to break up the plots. I'd like to be successful with this, so I am trying to follow their instructions.

Nuked my areas with glyphosate a week ago. Now waiting on my new sprayer to replace my POS sprayer. Ordered a jug of Simazine from Keystone as my pre-emergent. First read on this says 1 to 1.5 qts / acre......but I have read some do a higher rate. Much of my planting will be into a clover plot(s), where I have had problems with the clover out-competing the following crops.....even after killing it with glyphosate (clover comes back fast!). Thus my interest with pre-emergents.

My plan is to again nuke my clover area's when applying the Simazine.....hoping for a weed free start on the Sorghum.

My question becomes.....will the clover and rye I broadcast again in fall (Sept) be affected by the Simazine I put down now?

 

[FarmerDan]

My question becomes.....will the clover and rye I broadcast again in fall (Sept) be affected by the Simazine I put down now?

Probably.

If you want to plant back after simazine keep the rate on the low side. I would say you might be ok but it's getting late. Atrazine is a long residual herbicide. Simazine is a cousin formulated to be less so. In the days before glyphosate resistant crops we used atrazine and metolachlor (Bicep) pre-emergent to control weeds in corn where no fall crop would be planted. Simazine and metolachlor on corn fields being planted with winter wheat after October 1. So, where I am there was a 5-month breakdown window. You also need to be aware of your soil structure. High amounts of organic matter inhibit breakdown. Or, to put it another way, we used less herbicide where such soils were present. A dry/drought condition will also retard herbicide breakdown.

 

[T-Max]

Dan, I used Acuron which contains the following chemicals for the first time this year. They actually suggest a higher rate for higher OM soils. 2.5qt/acre for ac 3% or higher. The plant back interval for many of the small grains is 4 months. It says that cover crops may be planted provided they are not grazed within specified time frames.

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[Bill]

Plain old 2-4d should whack the clover and not hurt the sorghum post emerge.

 

[swat1018]

If you're wanting screening more than grain, plant a higher population of sorghum. Once it canopies you won't have a weed problem. I never use a pre with sorghum and get pretty good stands with plenty of grain, and not much weed due to the canopy height.

 

[Foggy47]

^^^. Good info guys. Some good insight here.

 

[Wind Gypsy]

Northwoods actually mentioned last year that some of the recommended simazine rates were high enough to injure their sorghum. I’d just keep it on the low side. I’m a little behind you on this years screen planting. Haven’t sprayed yet but I’m at least a week out from planting. Needs to stop raining!

 

[FarmerDan]

Dan, I used Acuron which contains the following chemicals for the first time this year. They actually suggest a higher rate for higher OM soils. 2.5qt/acre for ac 3% or higher. The plant back interval for many of the small grains is 4 months. It says that cover crops may be planted provided they are not grazed within specified time frames.





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Damned facts! Good catch. Herbicides are a complicated subject. As I have written in other posts labels are based on good research. Rely on the research and not too much on what we post here. Memory is a funny thing. Mine is old and often confused. I would still caution about the impacts of carry-over of the 'triazines on any following crop.

 

[T-Max]

Damned facts! Good catch. Herbicides are a complicated subject. As I have written in other posts labels are based on good research. Rely on the research and not too much on what we post here. Memory is a funny thing. Mine is old and often confused. I would still caution about the impacts of carry-over of the 'triazines on any following crop.

Do you know if the plantback intervals are labeled because of the potential for chemical compounds to end up in the forage? Or because the residual will likely hinder germination? Or both? Hard to find a solid answer on that.

 

[FarmerDan]

Do you know if the plantback intervals are labeled because of the potential for chemical compounds to end up in the forage? Or because the residual will likely hinder germination? Or both? Hard to find a solid answer on that.

There's no doubt some of the herbicide compounds end up in the plant. The basic idea in herbicide formulation is to find plants that can metabolize a herbicide and survive while others cannot.
The concern then is unintended human or animal consumption of these chemicals. The question is about how long it takes a desired plant to "digest" those added chemicals.

A pre-plant herbicide needs to be in the soil so that when target-plant seeds germinate the process is stopped. So, I would say the answer is BOTH. But I think most of the concern for planters is the effect of future crop germination and yield.

 

[Wind Gypsy]

@Foggy47 , took some pics of the ground inside last years NWW hd sorghum screen today. It got disced and sprayed with simazine when I planted the screen last year, hasnt been touched since. Still pretty dead looking except in one spot where a horsetail infestation is booming.. on either side of this you can’t see dirt through the vegetation.

 

[SD51555]

@Foggy47 , took some pics of the ground inside last years NWW hd sorghum screen today. It got disced and sprayed with simazine when I planted the screen last year, hasnt been touched since. Still pretty dead looking except in one spot where a horsetail infestation is booming.. on either side of this you can’t see dirt through the vegetation.

View attachment 64974View attachment 64975

I’ve got a banner stand of HT too this year. I even whacked this spot really hard with lime a year or two back. Like it never happened.

But it just started raining for the first time in three years. Lots of things are showing bumper crops in the wilderness this year.

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[Brokenbear]

I have done pretty good with nuke the whole thing with Gly then a medium dose of 2/4D a day later then wait one rain and plant ..the switch grasses n tall sorghum (AKA "screen") and has generally out distance any of the knocked back grass n broad leafs ..and usually will quickly shade out struggling grass providing your germination is good and well populated with new plants
Also if I am remembering correctly "some" of the really tall "sorghum" based screens are one and done and require replanting each year and additionally ..should not be grown in the same ground more than 2/3 years before moving the screen to new ground ...
So I am banding NW "HD" with NW RC BigRock to be able to "rotate"

Bear

 

[Wind Gypsy]

I have done pretty good with nuke the whole thing with Gly then a medium dose of 2/4D a day later then wait one rain and plant ..the switch grasses n tall sorghum (AKA "screen") and has generally out distance any of the knocked back grass n broad leafs ..and usually will quickly shade out struggling grass providing your germination is good and well populated with new plants
Also if I am remembering correctly "some" of the really tall "sorghum" based screens are one and done and require replanting each year and additionally ..should not be grown in the same ground more than 2/3 years before moving the screen to new ground ...
So I am banding NW "HD" with NW RC BigRock to be able to "rotate"

Bear

I might try to get some kanlow switch to add to mine this year as well. I doubt switch would ever get tall/thick enough to be a rock solid screen for my application though. Just need about 15 more years of spruce growth..