# Best Pre-M for next spring?



## cshults (Jul 9, 2018)

Hi all,

I'm starting to think ahead for next spring and what Pre-M to use to prevent the following in my newly reno'd KBG, Rye, Fescue lawn.


Crabgrass
Barnyard grass
Bentgrass
Foxtail
Ground Ivy
Purslane

I've heard Prodiamine is a widely used Pre-M and many recommend it, but it doesn't control all of the above. Tenacity (Mesotrione) apparently does control all of the above, but I haven't heard much about it being used as a Pre-M..

Would love to hear from folks that have used these products and how effective they were when applied at the proper time.

Thank you!


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## SNOWBOB11 (Aug 31, 2017)

Tenacity isn't a true long lasting pre-m. It's good for seed down to prevent unwanted weeds from germinating when trying to establish grass, but won't last for the season. Either prodiamine or dimension (active ingredient dithiopyr) would be good to use and will stop the germination of most weeds.


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## cshults (Jul 9, 2018)

Thanks, SnowBob. Hadn't heard of Dimension but after looking into it, it controls 1 more of my problem weeds than Prodiamine but neither take care of bentgrass. I think my plan of attack will be an initial application of Dimension and then a follow up with Tenacity later on in the spring to get the bentgrass.


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## g-man (Jun 15, 2017)

PreM prevent the plants from establishing roots shortly after germination (they do germinate). They wont kill weeds already established. It is great against stuff that produces seed (crabgrass, poa a, foxtail)

Some of the ones you list, will be there next year unless you treat them a herbicide. Tenacity is a great option at seed down, but the effect only last around 30days. Tenacity could also be used to control some post emergent weeds (aka herbicide). It is not the best one for some of the one you listed, and it is slow. Sometimes, Tenacity is the only good option outside of roundup (nimblewill, bentgrass).


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## Chris LI (Oct 26, 2018)

Matt Martin (The Grass Factor) has a great YouTube lecture on the similarities and differences between Barricade (Prodiamine) and Dimension (Dithiopyr). Oversimplifying it a little, generic Barricade is cheaper with longer residual, but Dimension has a little control of crabgrass in the early stages (1-3 tillers, I think). There are risks associated with both, as far as efficacy is concerned. Split apps of Dimension are sometimes suggested. Also, if you need to overseed next fall, you may need to break the PreM barrier, if you use Barricade.


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## NewLawnJon (Aug 3, 2018)

One thing to consider in a spring pre-m is what are your plans for the fall.

Prodiamine (Barricade) can be put down at a higher rate to get a longer residual effect, but it needs to be down before the ground temp is 60 degrees to prevent crab grass, and many other weeds from germinating.

Dithiopyr (Dimension) has both pre, and some early post emergence control if you miss the 60 degree window. Dimension tends to last about 4-5 months which gets you to August/September where you will be deciding between another application for winter weeds or over seeding/renovating.

I know that for my yard areas around mulch beds, and full sun warm up above 60 quicker than the shaded areas, so make sure you are looking for the warmest parts of the yard when considering.

Another area to consider is granular vs. liquid applications. Granulars are easy to spread, however the pre-m is on the granular, so you rely on even distribution of the granules and watering to spread the pre-m over the ground. A liquid application relies on you spraying it evenly to get an even and full distribution on the ground.


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## ForsheeMS (May 21, 2018)

I use Prodiamine but Dimension will also control all of the weeds you mentioned as well. Neither will keep bentgrass or ground ivy from coming back as they go dormant during the winter and reemerge in the spring. For those two you will have to use the appropriate herbicide while they are actively growing to kill roots and all. Pre-emergents will only prevent weeds germinating as seeds. Anything with established roots or stolons will not be affected by it.


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## TN Hawkeye (May 7, 2018)

Given Dimensions ability to hit young crabgrass as a post em I'm planning on spraying prodiamine in the spring and then using dimension in early summer. That way if I have any break through of crabgrass I can kill off the young plants and get a little extra protection in the summer against germination.


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## Chris LI (Oct 26, 2018)

TN Hawkeye,

Please check out Matt Martin's lecture on YouTube, as I referred to above. He cautions against your plan and gives his reasoning. Essentially, it's mixing apples and oranges, because the herbicides work a little differently from each other.


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## g-man (Jun 15, 2017)

I linked this study in the cool season guide, but I do want to highlight it. It shows a few important elements.

1) too low of a rate in spring only (treatments 4, 8, 12) and the protection broke down by August.
2) prodiamine provides better control than the others.
3) split applications provide better control and longer control.

https://turf.purdue.edu/report/2011/PDF/15_AGRY_Patton_sequential%20apps.pdf


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## TN Hawkeye (May 7, 2018)

Chris LI said:


> TN Hawkeye,
> 
> Please check out Matt Martin's lecture on YouTube, as I referred to above. He cautions against your plan and gives his reasoning. Essentially, it's mixing apples and oranges, because the herbicides work a little differently from each other.


I've watched that video several times and he is talking more about people putting split apps. I plan to run the 6 month rate of prodiamine in early spring and then spike it with dimension in early summer. He is speaking about people that put out a split app of prodiamine and then expect the dimension to prolong the effectiveness. I know that is not the case. He even says at the 11:10 mark that running a full rate of prodiamine and then a full rate of dimension will add to your level of control. @thegrassfactor please correct me if I'm wrong but my thinking is if I put out 6 month control of prodiamine and then use dimension to catch any crabgrass that has broken through in early summer I am still getting 6 months of prodiamine control plus some post em benefit from the dimension.


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## Suburban Jungle Life (Mar 1, 2018)

@TN Hawkeye That makes me wonder. If you see crabgrass, was the coverage from the prodiamine uniform? Were spots missed? Was there heavy traffic or bare dirt (uv degradation) and therefore a split app of 3 mo each a better solution? I'm thinking quinclorac sprayed along with the prodiamine for the 2nd app might give you better control if you have breakthrough. Also, quinclorac controls more weeds post than dimension and since you are combining it with prodiamine, then you have your pre-m anyway. If you have weed breakthrough, you would have to use a weed killer anyway, so why not split the prodiamine and add quinclorac as your post weed killer? Unless your growing season is so long that you reach max rates of prodiamine and need another pre-m....


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## NewLawnJon (Aug 3, 2018)

I would argue that whenever possible a split app is always better.

Matt Martin did talk about the differences and his preference is a high rate of prodiamine, but from running a lawn business you want to apply once and be done.

For a home owner a split app will always get as good of, if not better results as one high app rate. With heavy rains, differences in turf density, and other means to degrade the barrier a split app is going to overcome all of these.

My other argument for the split apps is that if you apply in April at a 4 month rate the pre-m is wearing off right when you need to decide between reapplying, or getting ready for over seeding or other lawn projects where you don't want the pre-m.


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## TN Hawkeye (May 7, 2018)

Suburban Jungle Life said:


> @TN Hawkeye That makes me wonder. If you see crabgrass, was the coverage from the prodiamine uniform? Were spots missed? Was there heavy traffic or bare dirt (uv degradation) and therefore a split app of 3 mo each a better solution? I'm thinking quinclorac sprayed along with the prodiamine for the 2nd app might give you better control if you have breakthrough. Also, quinclorac controls more weeds post than dimension and since you are combining it with prodiamine, then you have your pre-m anyway. If you have weed breakthrough, you would have to use a weed killer anyway, so why not split the prodiamine and add quinclorac as your post weed killer? Unless your growing season is so long that you reach max rates of prodiamine and need another pre-m....


This is my first year applying pre-em so I am far from an expert. I actually forgot that I was in the cool season forum. I had crabgrass in a lot of areas this summer but that was with no pre-em at all. Given some of the advice given here I am going to give some thought to how I want to tackle my applications next year. I did put out prodiamine and simazine on my Bermuda in September and due to a measuring error I am going to do another app late this month.


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## Avalawn T (Sep 11, 2018)

Quick question about spray tip output. I have a chapin 4 gallon backpack, can I use the standard fan tip that it comes with or do I need a heavier spray flow. It seems to me to get it to the ground I would.


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## thegrassfactor (Apr 12, 2017)

NewLawnJon said:


> I would argue that whenever possible a split app is always better.
> 
> Matt Martin did talk about the differences and his preference is a high rate of prodiamine, but from running a lawn business you want to apply once and be done.
> 
> ...


I prefer split apps, but getting the first one down early. I think there was research out of NC state that said a single app of a full rate (whatever % AI you want to get down for crabgrass control) provided better control than crabgrass. In my personal experience, I've always had better results running a split app. There is a caveat to running a split app. If i got my first application down after Mar 15, I've always had poorer results than my first app down prior to Mar 15. This has been true of my area of east TN. It was even earlier when I lived further down south.

Again, IMO JMO, split apps with first app down as early as possible > single app high rate.

Also my opinion - you should not go less than 1.0lb AI of prodiamine. You can apply that as .6 + .4 or .5+.5, but not - .5 AI prodiamine + .25 AI dithiopyr.

In the video, I was alluding to people running split rate app of prodiamine and a split rate app of dithiopyr. One of the most common questions I get is "i put down prodiamine and then dimension and i still had crabgrass. how is that possible" - as you dive deeper, you realize what happened. That compounding effect from Prodiamine + prodiamine doesn't exist with Prodiamine + dithiopyr.

Remember you must apply dithiopyr at a .5lb AI rate with a surfactant to get post-emergent control.


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## craigdt (Apr 21, 2018)

g-man said:


> I linked this study in the cool season guide, but I do want to highlight it. It shows a few important elements.
> 
> 1) too low of a rate in spring only (treatments 4, 8, 12) and the protection broke down by August.
> 2) prodiamine provides better control than the others.
> ...


Looks like the link changed to this location:
https://turf.purdue.edu/report/2011/PDF/15_AGRY_Patton_sequential apps.pdf


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