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Crabgrass Pre-Emergent too early or too late

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Myrick Willard

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Discussion starter · #1 ·
If Crabgrass doesn't start coming up until Late June/Early July... is it really necessary to start applying Pre-Emergents (like Dimension, Barricade, Stonewall, etc.) as early as March or even April? Could you not just wait until say 1st or Middle of May to apply?

Also... As far as the "timeline" for Seeding or Over-Seeding when it comes to Pre-Emergents: How long do you have to wait after you've seeded or over-seeded before you can apply the Pre-Emergent? And also, how long do you have to wait after you've applied the Pre-Emergent before you can seed or over-seed?

Thanks!
 
#2 ·
I think your late on the crab control unless your doing a split app (good idea this year). Pre em shouldn't go down until you are certain you have near max germination. Even then I would rather focus on building a strong stand of turf for weed control and spot spraying really bad areas or hand pull and reseed those areas. The less chems around new grass the better is my theory. Strong turf Is your best weed control.
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#3 ·
I start out early like every one else to do the pre but in my owne personal yard i don't do the pre till the end of may or the start of june and i don't have crab grass. But i have seen yards with crab in the start of may so it will depend on the yard and how they cut the grass and bare spots and such. But my yard is one if you have many to do you may not get them all done before you get crabgrass germinating in a cost wise it would be cheaper to get the pre down early before it germinates. hand spraying crab grass can be costly and time consuming.
 
#4 ·
You never know in advance what the soil temperature is going to be. Some years it germinates early and some years late. That is why many do split applications.
 
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Discussion starter · #5 ·
Yeah I see what you guys are saying. I was also wondering about the "timeline" for Seeding or Over-Seeding when it comes to Pre-Emergents: How long do you have to wait after you've seeded or over-seeded before you can apply the Pre-Emergent? And also, how long do you have to wait after you've applied the Pre-Emergent before you can seed or over-seed?
 
#7 ·
I think your question has too many regional variables...such as new england, who knows what can happen....our springs and falls can be as hot or cold as summer or winter. Bottom line ( which i hate to agree with) is it comes with volume of accounts and time it takes to apply.....personally i dont apply anything until at least mid may
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#10 ·
Well I did one app of prodiamine and it was a major mistake. I have been told doing a follow up in the early summer with prodiamine can be very beneficial. That would be my round three in PA. I am at my wits end and I am going to try it next season.
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#11 ·
Personally I cant afford to wait to much longer than when the season is underway a few years back it got hot in april mid 75s for a few days and the stuff popped much earlier than normal which is not worth the risk to me. Its much cheaper and less time consuming to apply a preemergent than to walk around and spot spray crabgrass with acclaim or drive.,. plus I try to minimize extra customer requested visits in anyway that I can to keep them happy and keep me on schedule.. Ive never had a problem with crabgrass doing two treatments with preem unless the lawns are thin or we have extended heat waves late in the season. Preem also helps to prevent weeds so its a win win to go out the door with preem imo.
 
#12 · (Edited)
My rule of thumb is to apply crabgrass pre-emergent before the afternoon high temperature in your town gets over 80 degrees F. About May 10 in my area. Naturally if you have a lot of customers, you have to start early, to be sure. Weather can vary. Remember when crabgrass first appears, the tiny sprouts are almost invisible, less than a quarter-inch. Only experienced experts will spot it.

In my experiments, as I recall, I had to wait 80 days before new seed would germinate in treated soil. As stated above it depends on the product and how much was applied, and also other factors.

Usually you can treat new grass with crabgrass control after the second mowing. About 6 to 8 weeks after seeding.

http://www.lawnsite.com/showthread.php?t=425042&highlight=seed+crabgrass+control
 
#13 ·
Weeds germinate at a certain soil temp. So getting pre down before that temp is critical in preventing weeds.

What most of us often see is crab in late summer due mostly from spring pre wearing off or heat/drought stressed turf.

You also need to consider pre timing. In theory a summer pre app would hurt fall fescue seeding.
 
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#14 ·
you can get crabgrass up real early i have seen it bu then evening frosts kill it. But like Herpes it keeps coming back. So for the first time in 15 years i will do split apps of preee. I am sick and tired of spending 3 to 4 grand every year on post. now customers that have been with me 3 years or more dont get it at all. because i dealt with it the first 3 years.

on another note does anyone here spray prodiamine or dimesion from a turfco or permagreen?
 
#15 ·
grassmasterswilson said:
Weeds germinate at a certain soil temp. So getting pre down before that temp is critical in preventing weeds.

What most of us often see is crab in late summer due mostly from spring pre wearing off or heat/drought stressed turf.

You also need to consider pre timing. In theory a summer pre app would hurt fall fescue seeding.
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This is so true. I'm waiting to spot spray some post for crab but its too dog on hot.
 
#18 ·
How hot is too hot. Depends on turf type.

I really do t spray anything on the few fescue lawns I have here in the south. Mid 90s and humid causes all kinds of stress on my fescue anyway.

Warm season turf I have no restrictions unless it's a drought. Just need to watch surfactant rates in my opinion
 
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