Why isn't my pre-M working?

Kentucky bluegrass, Fescue, Rye and Bent, etc
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micvog
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Why isn't my pre-M working?

Post by micvog » May 26th, 2017, 8:16 pm

The last two years I have had widespread weed issues in my lawn despite using a pre-M. I am trying to figure out what I am doing wrong.

Last year I used the Hi-Yield Dimension product at bag-rate in late March and early August. I have had challenges establishing a new KBG lawn so I attributed the weeds more to the lack of a thick, tall lawn than a pre-M failure. But since I am having problems this year, I am not sure.

This year I put down Quali-Pro Prodiamine 65 WDG at the 0.75#/A rate in late March. I used the fan tip that came with my Chapin 20V backpack sprayer and I am confident that I applied it evenly as I used a tracker dye. However, I used 16G of water to cover 10K square feet which seems to be more diluted than most (but since I am applying more diluted product to get the same AI per area, I assume it doesn't matter).

Is the fan tip the problem?

My lawn has been really slow to wake up both years. Is that giving the weeds a head start? Would switching to PRG help control my weeds? (I think I can convince my wife to allow me to reno part of the lawn.)

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Re: Why isn't my pre-M working?

Post by andy10917 » May 26th, 2017, 8:22 pm

Why do you feel that PRG would make a diiference? (just curious)

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Re: Why isn't my pre-M working?

Post by micvog » May 26th, 2017, 8:30 pm

My thought is the PRG wake ups earlier so it would get thicker/taller earlier and crowd out the weeds before they get established.

Right now my lawn is slow to wake-up (spotty growth on Memorial Day weekend; last year I had spotty growth until late July) and it appears to me the weeds get established and start growing before the lawn fully wakes up. Maybe that's because my lawn is only 1.5 years old? Because Bewitched is just late to wake-up generally? Because my soil still needs work (soil test at viewtopic.php?f=11&t=22297)?

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Re: Why isn't my pre-M working?

Post by andy10917 » May 26th, 2017, 8:37 pm

PRG is not a miracle grass. If KBG is late to rise, so will PRG be late. Find out what is wrong with the Pre-M app (hint: it's prolly not the Pre-M) and the late-wakening (when do the neighbors wake up?). Then fix it.

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Re: Why isn't my pre-M working?

Post by micvog » May 26th, 2017, 8:47 pm

Yep. Thinking I need to get a different tip for my sprayer. The fan tip seems to result mostly in a foliar application where I am assuming the pre-M needs to get to the soil so I need bigger droplets.

I live in a new development, and with one exception, the neighbor's NoMix lawns are also late to wake up.


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Re: Why isn't my pre-M working?

Post by Green » May 26th, 2017, 8:51 pm

Also, Pre-Ms don't prevent all annual weeds. If you can ID the weeds, and compare to what your Prodiamine protects against, it could be that you have stuff that's not impacted much by it.

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Re: Why isn't my pre-M working?

Post by andy10917 » May 26th, 2017, 8:55 pm

Thinking I need to get a different tip for my sprayer. The fan tip seems to result mostly in a foliar application where I am assuming the pre-M needs to get to the soil so I need bigger droplets.
I dunno. I would think that a tip problem would show itself as uneven effectiveness. I'd consider remeasuring the area if the planned amount came out correct against the actual amount used.
I live in a new development, and with one exception, the neighbor's NoMix lawns are also late to wake up.
Unless you're using the Aggressive Fall Regimen, do not expect to be out of line with other nearby lawns.

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Re: Why isn't my pre-M working?

Post by ligrass » May 26th, 2017, 9:55 pm

micvog wrote:
May 26th, 2017, 8:30 pm
My thought is the PRG wake ups earlier so it would get thicker/taller earlier and crowd out the weeds before they get established.

Right now my lawn is slow to wake-up (spotty growth on Memorial Day weekend; last year I had spotty growth until late July) and it appears to me the weeds get established and start growing before the lawn fully wakes up. Maybe that's because my lawn is only 1.5 years old? Because Bewitched is just late to wake-up generally? Because my soil still needs work (soil test at viewtopic.php?f=11&t=22297)?
You thought right. The PRG I planted last September was fully awake 6+ weeks before my KBG. It's weed free and doesn't play nice with Poa. Whether it's allelopathy or it hogs all the resources because of faster green up, I'm not sure (I think it's a little of both).
2 caveats, I have yet to see how it performs over the summer. And it needs plenty of sun to thrive (more than KBG). By the way, it was the darkest turf on my block the last 2 months.

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Re: Why isn't my pre-M working?

Post by andy10917 » May 26th, 2017, 10:07 pm

LIGrass, your example ignores the fact that if there is a nutrient problem, it will affect PRG in the same manner that it affects KBG. There is no magic in PRG.

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Re: Why isn't my pre-M working?

Post by bernstem » May 27th, 2017, 7:33 am

I also think there are two things going on. The slow wake-up and thin turf suggests a nutrient deficiency. I would look at past fertilization, irrigation and mowing practices. The excess weeds are a second problem. One possibility (though not likely) would be a failure of the pre-emergent. Unless there was an application dosing error, that is unlikely. Even using a foliar sprayer tip vs a droplet tip won't matter. The pre-emergent will sit wherever you put it until rain or irrigation carries it to the soil. It is more likely that your weed pressure is so high that the breakthrough weeds are more than you like or that you are dealing with perennial weeds.

A couple questions to start...
1. What weeds are you dealing with?
2. Do you have photos of the lawn?
3. What is your fertilization regimen?

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Re: Why isn't my pre-M working?

Post by g-man » May 27th, 2017, 8:13 am

bernstem wrote:
May 27th, 2017, 7:33 am
The pre-emergent will sit wherever you put it until rain or irrigation carries it to the soil.
I agree with your post but this part. If there is a torrential downpour, it could get watched away if it is wasn't watered in. We had a few heavy downpours in Indy this year.

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Re: Why isn't my pre-M working?

Post by Billy » May 27th, 2017, 8:16 am

The first step here is identifying the weeds that you say are causing problems. If they're perennials, it doesn't matter how much PRE you use.

I'm not really in the nutrient deficiency camp here, unless you're seeing specific nutrient deficiency symptoms. Overdosing on N can mask a lot of sin, which will reveal itself when the weather gets stressful, like that stretch of hot days right around your 4th of July BBQ you invite the neighbors to.

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Re: Why isn't my pre-M working?

Post by micvog » May 27th, 2017, 10:40 am

Thanks everyone.

Per my soil test, I have a heavy, alkaline soil. My calcium:magnesium ratio is out of whack, but neither of those macro-nutrients is deficient. My phosphorous is low (156#/A this Spring, was 114#/A last Spring). Based on what I did last year and the impact, by interpolation I am estimating I will have 211#/A next Spring based on my current plan.

I was thinking I could put some gypsum down but Andy recommended I hold off since my year-over-year comparison looked like one of the tests was an outlier. My next door neighbor recently submitted his soil test which leads me to believe this year's result is more accurate.

I winterized with Urea last Thanksgiving. When the snow melted the lawn was green with few weeds. However, the lawn sits there as the weeds grow. So far this year I put down 0.9#/M of N from Milorganite on 4/29 and 5/10. Yesterday I put down 20#/M of cracked corn, 8#/M of Alfalfa, and a half-bag-rate of Milorganite. This morning I put down 3oz/M of Serenade.

I am horrible at identifying weeds so I will take some pictures and look online to see if I can identify them. I do have clover, a dandelion or two, and something that looks like henbit, among others.

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Re: Why isn't my pre-M working?

Post by GaryCinChicago » May 30th, 2017, 12:16 am

micvog wrote:
May 26th, 2017, 8:47 pm
Yep. Thinking I need to get a different tip for my sprayer. The fan tip seems to result mostly in a foliar application where I am assuming the pre-M needs to get to the soil so I need bigger droplets.


Irrigate after applying and the product infiltrates the soil.

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Re: Why isn't my pre-M working?

Post by GaryCinChicago » May 30th, 2017, 12:36 am

micvog wrote:
May 26th, 2017, 8:16 pm
I have had challenges establishing a new KBG lawn so I attributed the weeds more to the lack of a thick, tall lawn
micvog wrote:
May 27th, 2017, 10:40 am
So far this year I put down 0.9#/M of N from Milorganite on 4/29 and 5/10. Yesterday I put down 20#/M of cracked corn, 8#/M of Alfalfa, and a half-bag-rate of Milorganite. This morning I put down 3oz/M of Serenade.



Are you basing this on GDD?
I suggest you Google MLSN, Dr. Micah Woods and Pace Turf for minimal feeding guidelines.

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Re: Why isn't my pre-M working?

Post by micvog » May 30th, 2017, 10:23 am

Thanks everyone.

@GaryCinChicago. By GDD do you mean "growing degree days"? Then yes, I use that to time my pre-M app at around 225-250 GDD. I don't have a forsythia in my yard, but there are a handful of plants in my yard that begin to bud (not bloom) right around the same time as the 225-250 GDD value. I am assuming if anything I may be a little early but I am still able to cover the entire season using two 0.75#/A apps of Prodiamine 65 WDG so I don't worry about it.

I did find an abstract of the document you referenced. I guess that goes to a philosophical disagreement on the forum - some put down heavy amounts of Milorganite, grains, and other organic/slow release food/fertilizer, and others discourage heavy use of those items, especially in the Spring. My approach has been that (1) I don't live in the transition zone so that gives me some more flexibility, (2) my soil needs the organic matter and phosphorous provided by Milorganite per the soil test interpretation provided by ST6, and (3) if I am keeping my lawn properly watered, and my fertilizer regimen still allows me to follow the "1/3rd Rule" and only mow once a week, even during what should be "Spring Flush", then I am not stressing my lawn. At $6/bag I am not concerned if I am putting down the minimum amount of fertilizer; I can afford to indulge a hobby. I am willing to be corrected... and based on my results I probably do need to be corrected... but that is how I have "synthesized" what I have read on the forum.

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Re: Why isn't my pre-M working?

Post by mtroberts20 » May 31st, 2017, 11:31 am

micvog wrote:
May 27th, 2017, 10:40 am
I do have clover, a dandelion or two, and something that looks like henbit, among others.
Clover and dandelion are both perennial weeds. If you don't kill them some other way then your pre-M will do nothing to what is currently there.

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