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Larson Lawn Care
04-02-2010, 08:43 PM
A mowing customer of mine asked me if it was too late for a pre emergent, I told him I had no clue, but the weeds may already be growing. What can I tell him?

clydebusa
04-02-2010, 08:49 PM
The big question for pre-emergent weed killers is when to apply them. Pre-emergent herbicides only work if they are applied to your lawn before the weed's growth period. But if applied too early, weather will dilute the herbicide and the weed will grow unencumbered.
Two dates to remember are March 15 and September 15. Those are the two dates of the year around which pre-emergent fertilizers should be applied so that they activate before seasonal weeds make an appearance.

Ofcourse this could change depend on the zone you are in. In St Louis you could go closer to April.

Larson Lawn Care
04-03-2010, 02:15 AM
So its too late?

grass4gas
04-03-2010, 07:14 AM
It is all based on soil temps. When soil temps hit 55 degrees for 4-5 days in a row, crabgrass will begin to germinate shortly thereafter.

What are your daytime temps in St. Louis? If you been having cool temps, you are fine.

Get a soil thermometer or check with your local extension office.

My theory is even if crab has germinated, put a pre down anyway. You are going to get a certain % of control as it is. Putting nothing down means no control of any kind.

Turfdoctor1
04-03-2010, 09:32 AM
grass4gas is right.

Preventing crabgrass is your main goal when putting out your spring pre-emergent. You may have a little effect on broadleaf weeds, but not much. The main emphasis is getting the crabgrass prevented.

It is recommended to have it down by now, but you are still fine. I'm several hours south, and we certainly have not seen any crabgrass germination yet. You are without a doubt still ok up there.

Boomer Sooner
04-03-2010, 01:50 PM
Apply Liq Dimension with msma, if you catch it in early stages,it will get most of it,crabgrass is not up yet, but I expect to see some this next week in Tulsa, broadleaf weeds will be controlled with the post app- most of time it takes a full season to control crab,theres no miracle wonders in one app

jose85
04-03-2010, 07:42 PM
just like the guy said , its always ok as long as the soil temp is still below 55


The big question for pre-emergent weed killers is when to apply them. Pre-emergent herbicides only work if they are applied to your lawn before the weed's growth period. But if applied too early, weather will dilute the herbicide and the weed will grow unencumbered.
Two dates to remember are March 15 and September 15. Those are the two dates of the year around which pre-emergent fertilizers should be applied so that they activate before seasonal weeds make an appearance.

Ofcourse this could change depend on the zone you are in. In St Louis you could go closer to April.

SOONER GREEN
04-04-2010, 12:58 AM
No it's not too late. Like they said, soil temps above 55 for @ 5 days will germinate crabgrass. I saw crabgrass in the single leaf stage today in my neighbors yard which is a south facing slope with sandy soil. The Oklahome mesonet shows the 3 day average 2 " under sod is 57, so it wont be long.Thats early for OKC, it's normally @ April 15th. Rd. 1 is fixin to come to an end.

RigglePLC
04-04-2010, 11:29 AM
If....you have frost...it kills crabgrass. So maybe you have a few more days. We used to figure that the last day for crabgrass control was the first frost-free-date in your city. About May 22 for us. If tiny crabgrass seedlings are not visible--it may work. Otherwise partial control.

Larson Lawn Care
04-04-2010, 12:22 PM
It was in the 70's/80's for a week here in St. Louis.

Jason Rose
04-04-2010, 12:39 PM
Use Dimension. If it's been that warm and your soil temps are around 55*. It's about to late for a product like barricade, as it takes a couple weeks for it to become active in the soil (very slow moving), By then you could potentially have crabgrass germed. and rooting down around the hot edges.

Dimension offers some POST-emergent control, and is about the best bet for late new customers.

A lot of people go by the Forsythias blooming as your indicator that you should have your preemergent down NOW. Some say the Redbuds, but frankly they are not a good guage as they bloom much later here. (the forsythias have flowered and are dropping petals and the redbuds are barely showing flower buds right now)

Boomer Sooner
04-04-2010, 01:38 PM
I think you can use drive also, for crab that is up, but very much cashola to apply

bx24
04-04-2010, 10:58 PM
I read on here the Pre-M and Dim both offer post emg on crag....So far Pre-M offers better weeds control then Dim.

I am not doing Drive 75 till end of April along with Dim...See what happens this year....Need to play with this stuff! LOL

Snapper12
04-04-2010, 11:02 PM
I'm convinced that nobody really has any actual answers that are factual regarding pre-m. Everybody is stuck between the label being law and what actually happens in the field.

jvanvliet
04-09-2010, 08:18 PM
It depends what zone you are located in... There's lot's of good advice herefrom people, but it relates to where THEY operate. For example, I'm in zone 10; I can put down barricade as early as middle of March, further North it's later. Ambient temps below 80 during the day and high 60's to mid 70"s overnight doesn't affect efficacy to a great extent... I put down more. When it warms up into the 80's & 90's, I douse the grass with diesel fuel and set it in fire... weed problem over. And I get a turf job :)

Greenery
04-09-2010, 09:31 PM
It depends what zone you are located in... There's lot's of good advice herefrom people, but it relates to where THEY operate. For example, I'm in zone 10; I can put down barricade as early as middle of March, further North it's later. Ambient temps below 80 during the day and high 60's to mid 70"s overnight doesn't affect efficacy to a great extent... I put down more. When it warms up into the 80's & 90's, I douse the grass with diesel fuel and set it in fire... weed problem over. And I get a turf job :)

Very true, during a normal year I wouldn't be applying mine for about a month here.

bx24
04-09-2010, 10:01 PM
I have put down dim the other day, 91F and others I have put down right after snow...I like Pre-M for weeds and Dim for non-staining. Both do post-emg too. Lastly, Pre-M is like 1/3 the price of Dim 2 vs Pre-M...But Pre-M smells cool! LOL

To me they are close and I could careless on the label...

DA Quality Lawn & YS
04-10-2010, 12:40 AM
It was in the 70's/80's for a week here in St. Louis.

Your right. This early warm up is going to push soil temps a bit. Better to apply your Rd1 on the early side this season, rather than the late side.