# Depth of Pre Emergent barrier



## LittleBearBermuda (Sep 25, 2020)

I hope everyone had a great Christmas.

I'm curious how deep a pre emergent barrier is. I assume core aeration will break the barrier? How about verticutting?

I'm having irrigation installed in February and wanted to apply another round of Prodiamine at .46 oz/m after the install. Then at the end of March or beginning of April I want to core aerate and level again. Should I apply a different pre emergent after the aeration or wait until I level the lawn then apply? I have on hand pennant magnum and spectical.

Thanks!


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## gpbrown60 (Apr 7, 2018)

LittleBearBermuda said:


> I hope everyone had a great Christmas.
> 
> I'm curious how deep a pre emergent barrier is. I assume core aeration will break the barrier? How about verticutting?
> 
> ...


I would wait until after dethatching, core aeration and leveling for your second round of pre-emergent. They say rotating preemergent modes of action is preferred but I would use what I have and worse case scenario follow-up with some post emergent spray if needed. :thumbup:


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## HarryZoysia (Aug 27, 2019)

Neither core aeration nor dethatching will "break the barrier" of preemerge. Rock on


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## rjw0283 (May 11, 2020)

I did a pretty thick sanding last summer at the end of May. I had a bunch of crabgrass pop up. I did do a spring prodiamine APP. (The seeds were in the sand) I applied a light rate of prodiamine after I noticed germination. My next sanding I'll try to apply a different MOA a week or 2 prior to the sanding or maybe directly after the sanding, or just do a more potent rate in the spring.

The crabgrass was easy to pull, I assume that the roots weren't able to grow deep due to the pre-e I applied a few months earlier in the spring. But a 1/2-1 Inch layer of sand is plenty of area for the crabgrass to germinate and build roots prior to it getting to the treated soil underneath.


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## LittleBearBermuda (Sep 25, 2020)

rjw0283 said:


> I did a pretty thick sanding last summer at the end of May. I had a bunch of crabgrass pop up. I did do a spring prodiamine APP. (The seeds were in the sand) I applied a light rate of prodiamine after I noticed germination. My next sanding I'll try to apply a different MOA a week or 2 prior to the sanding or maybe directly after the sanding, or just do a more potent rate in the spring.
> 
> The crabgrass was easy to pull, I assume that the roots weren't able to grow deep due to the pre-e I applied a few months earlier in the spring. But a 1/2-1 Inch layer of sand is plenty of area for the crabgrass to germinate and build roots prior to it getting to the treated soil underneath.


Thank you. Great info. I wasn't sure how the pre emergent would work on fresh sand.


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## rjw0283 (May 11, 2020)

should work fine, as you are going to probably water the crap out of it after sand. 
I'll also be hitting it with some fungicide just prior to sanding.


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## Redtwin (Feb 9, 2019)

rjw0283 said:


> I did a pretty thick sanding last summer at the end of May. I had a bunch of crabgrass pop up. I did do a spring prodiamine APP. (The seeds were in the sand) I applied a light rate of prodiamine after I noticed germination. My next sanding I'll try to apply a different MOA a week or 2 prior to the sanding or maybe directly after the sanding, or just do a more potent rate in the spring.
> 
> The crabgrass was easy to pull, I assume that the roots weren't able to grow deep due to the pre-e I applied a few months earlier in the spring. But a 1/2-1 Inch layer of sand is plenty of area for the crabgrass to germinate and build roots prior to it getting to the treated soil underneath.


I had the exact same thing happen after sanding. I will try to time my app this spring to shortly after my sand application just to see if I get a different result. I've used Prodiamine in the past with good control and any plants that make it through are easily pulled. In addition to adjusting the timing a little, I will also try rotating between Prodiamine and Simazine.


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## rjw0283 (May 11, 2020)

@Redtwin I've also added Simazine to the arsenal. I plan on doing the same with rotation of the 2. 
I also have Gallery (Isoxaben) for late spring to early summer to get everything else. Used it last year, spurge and other weeds I've had in the past were nonexistent.


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