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Smallaxe
01-03-2012, 08:40 AM
"In a dense stand of turf under a medium maintenance program it was found that soil temperatures greater than 73° F. were required for significant crabgrass seed emergence. It has also been reported that minimum temperatures of 55° to 58° F. at daybreak in the upper inch of soil for 4-5 days will encourage the initiation of crabgrass germination. Other research has shown that mean soil temperatures of 62° to 65° F. are required for germination."
http://viette.indigofiles.com/CrabgrassControl.pdf

Also this comment was made:
"This research suggests that under average turf density the germination and emergence of crabgrass can continue for up to 12 weeks during a typical growing season in the Northeast. An application of a preemergence herbicide too early in the season, before soil temperatures warm adequately, may result in the need for additional crabgrass control measures later in the season."

Smallaxe
01-03-2012, 08:47 AM
For me,,, this means that it is worth the trouble to form a denser stand of grass in the Spring, before CG becomes an issue, because the denser stand is going to push the CG back even longer...

Who out there does Springtime seeding of turf grass b4 the CG pre-m is applied???

RigglePLC
01-03-2012, 10:40 AM
Turbo?
Axe, seeding grass in spring and THEN applying crabgrass control is a tricky situation. One needs to get the new grass up as early as possible (about April 8th, for me), add growth, and then sock-on the crabgrass control before the soil temperature hits 73 degrees. (or 55 or 65 depending on which expert your believe.)(Or maybe you prefer to use growing Degree Days base 50 [GDD50] of about 200). I suspect that perennial rye as a cool-season grass is fast enough to do it, if your timing is near perfect, as crabgrass is a warm season annual.

RigglePLC
01-03-2012, 02:19 PM
Last August I found that new grass I planted in containers was killed if it was about 2.25 inches tall at the time of treatment with Dimension. But two weeks later when the grass was about 3.5 inches tall, applied Dimension caused no injury.

Of course, new grass might be germinating and growing very slowly if the weather is cool. So...possibly...if new grass was planted about March 25 and it sprouted about April 8, (at 14 days)(due to cool soil). Then perhaps the new grass would be about 3.5 inches tall (at 21 days) (slowed due to cool weather). Then one would have about 14 days to treat the new grass with Dimension. If nothing went wrong. Under Michigan conditions.

Temperature last night was about 15 degrees here.

Smallaxe
01-05-2012, 08:15 AM
We're not likely to have a consistant soil temp. above 55 at daybreak 4-5 days in a row, in the upper 1" of soil, very early in the Spring... our ALF date is around mid-May...

Last year our earliest possible germination of CG in our area was around the 3rd week in May as it became visible in June... That was full sun... unprotected lawns not until late June, mostly July...

Do you believe it would be in everyone's best interest to apply the pre-m in regards to the timing of the germination process of CG itself, rather than the forsythia bloom?

RigglePLC
01-05-2012, 11:43 AM
Axe,
So true, I don't pay much attention to forsythia bloom--it is far earlier than crabgrass germination. Ideal time for crabgrass treatment around here, is when the air temperature first hits a high of about 75. About first week of May for us. This is also the time for the first or second mowing. About the time of dandelion bloom. Its about 3 weeks after grass greenup. Our first frost-free date is about May 20. Lake Michigan keeps us slightly cooler in spring.
Growing Degree Days is probably a better measure of when the crabgrass will germinate. Best to treat before GDD base 50 exceeds 200. Expect germination at about 1100.

In a practical sense, a lawn care firm cannot treat everyone on the best date. I usually treated crabgrass beginning when the snow melted. I tried to finish within 6 weeks, by about May 7th.

I kept data on the degree of crabgrass infestation of my customer's lawns giving them a crabgrass grade of 4, 3, 2, or 1. Like college, A,B,C or D. This record was eventually typed into my computer. I had data to show that the early dates were about equal to the late dates relative to crabgrass control. I also had data on the success of various products that I had used for crabgrass control over the years.

Smallaxe
01-06-2012, 09:50 AM
Axe,
So true, I don't pay much attention to forsythia bloom--it is far earlier than crabgrass germination. Ideal time for crabgrass treatment around here, is when the air temperature first hits a high of about 75. About first week of May for us. This is also the time for the first or second mowing. About the time of dandelion bloom. Its about 3 weeks after grass greenup. Our first frost-free date is about May 20. Lake Michigan keeps us slightly cooler in spring.
Growing Degree Days is probably a better measure of when the crabgrass will germinate. Best to treat before GDD base 50 exceeds 200. Expect germination at about 1100.

In a practical sense, a lawn care firm cannot treat everyone on the best date. I usually treated crabgrass beginning when the snow melted. I tried to finish within 6 weeks, by about May 7th.

I kept data on the degree of crabgrass infestation of my customer's lawns giving them a crabgrass grade of 4, 3, 2, or 1. Like college, A,B,C or D. This record was eventually typed into my computer. I had data to show that the early dates were about equal to the late dates relative to crabgrass control. I also had data on the success of various products that I had used for crabgrass control over the years.

That was an excellent post, with a great plan for taking care of lawns and the way you sequenced them... Did you ever get grade A lawns that you quit the CG pre-m altogether?

That highlights the problem of 'squirt and fert only', in that you need to start early on someone, just to make sure that everyone gets done b4 the deadline... Full service lawncare is got to be advantageous for that reason...

RigglePLC
01-22-2012, 09:29 PM
I never omitted the crabgrass pre-emergent; the customers expect it. And it is too difficult to carry two kinds of fert, and to empty the spreader and change formulas.

A full-service company would have an advantage there--especially if you had two spreaders and two fert formulas on your trailer.