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View Full Version : Best way to treat crabcrass in a organic way


JFGauvreau
04-09-2011, 06:59 PM
What if you can't use pre-emer, or chemicals to kill the crabgrass?

I know that crabgrass is a annual weed and will most likely be killed as the first frost comes in fall. (in Canada), but the seeds will remain on the ground, therefor creating new plants in spring.

Is crabgrass a type of weed that does not tolerate frequent mowing? If so, frequent mowing would eventually kill the crabgrass?

What are the other ways you can "Naturally" kill the crabrass? I am speaking of mostly Kentucky blue grass lawns, kentucky is good for choking out weeds at a 3" height, but crabgrass grows higher and sooner than that.

Any help would be appreciated.

Leo the Landscaper
04-09-2011, 08:29 PM
Corn Gluten Meal is the organic answer to preemergent herbicides.

AI Inc
04-10-2011, 06:46 AM
Better soil structure. Dont have an envirement where CG can thrive.

JFGauvreau
04-10-2011, 08:12 AM
Corn Gluten Meal is the organic answer to preemergent herbicides.

Doesn't corn gluten meal attracts a lot of ants?

Better soil structure. Dont have an envirement where CG can thrive.

What kind of soil crabgrass doesn't thrive in? We have mostly clay here.

Leo the Landscaper
04-10-2011, 09:11 AM
Doesn't corn gluten meal attracts a lot of ants?



What kind of soil crabgrass doesn't thrive in? We have mostly clay here.

There isn't one! I think he means develop a strong thick turf by way of developing a healthy soil which will compete better against the crabgrass.
Posted via Mobile Device

Smallaxe
04-10-2011, 10:17 AM
I never use CG pre-M on turf...

CG, is a low growing grass that fills in vacant, hot, dry spots in the dirt, that are not being used by other grasses... They can live off dew in such a way that it thrives, during the same time KBG is slowing down, even going dormant in the summer heat...

Mulch mowing, keeps the soil cool and protected for KBG roots and Rhyzomes to grow into... Mowing higher when the heat comes does the same thing... Not fertilizing just b4 or during the heat is an important practice...

This business about CGM for pre-m, and a 2yr buildup to prevent 80% of seed germination... begs a simple question, When can one overseed???

ICT Bill
04-10-2011, 12:20 PM
I never use CG pre-M on turf...

CG, is a low growing grass that fills in vacant, hot, dry spots in the dirt, that are not being used by other grasses... They can live off dew in such a way that it thrives, during the same time KBG is slowing down, even going dormant in the summer heat...

Mulch mowing, keeps the soil cool and protected for KBG roots and Rhyzomes to grow into... Mowing higher when the heat comes does the same thing... Not fertilizing just b4 or during the heat is an important practice...

This business about CGM for pre-m, and a 2yr buildup to prevent 80% of seed germination... begs a simple question, When can one overseed???

for KBG 3 weeks before or 3 weeks after seeding

JFGauvreau
04-11-2011, 05:50 AM
Ok thanks for your help guys

AI Inc
04-11-2011, 06:22 AM
There isn't one! I think he means develop a strong thick turf by way of developing a healthy soil which will compete better against the crabgrass.
Posted via Mobile Device

Correct, crabgrass does thrive worse in a sandy soil. A healthy turf in loam will fight it off better.

Smallaxe
04-11-2011, 09:18 AM
for KBG 3 weeks before or 3 weeks after seeding

Could I also sow CG 3 weeks b4 and 3 weeks after?

(A root inhibitor pre-m lasts for 90 days, and kills every seed that germinates)...

What is the system that makes CGM special?

ICT Bill
04-11-2011, 05:05 PM
Could I also sow CG 3 weeks b4 and 3 weeks after?

(A root inhibitor pre-m lasts for 90 days, and kills every seed that germinates)...

What is the system that makes CGM special?

it doesn't last 90 days more like 6 weeks that is why timing is so critical with CGM, if you are going after CG it should be applied as the soil temp is rising from 60 to 65

Dr.NewEarth
04-11-2011, 10:33 PM
Crabgrass simply says that, the soil is low in calcium and that it cannot support decay starting with actinomycetes molds.

It is usually possible to adjust the system in a year or two, putting a little calcium lime and sulphur or gypsum on the soil in order to restructure the pH.

As this is accomplished, most of the infestation dissipates, virtually rotting away.

Usually application can be computed on the basis of 1500 pounds of high calcium lime per acre, 30-40 pounds of processed and active sulfur per acre. If ammonium sulfate is used, a little more calcium is required.

so, I would check your pH and raise or lower it accordingly so that you get as close to
a neutral aka 7 on the pH scale.

You can get a pH kit at the H.D. I just picked up one in the spa department.
I think it was 15 dollars for a couple dozen tests.

A basic soil test kit there is about twenty dollars. It will give you the macro nutrients levels only.

Kiril
04-11-2011, 10:56 PM
Crabgrass simply says that, the soil is low in calcium

Crabgrass will grow fine in soils with high Ca. Don't assume anything here! Using these types of plant indicators merely tells you what might be occurring, and that you need to get a soil test.

Usually application can be computed on the basis of 1500 pounds of high calcium lime per acre, 30-40 pounds of processed and active sulfur per acre. If ammonium sulfate is used, a little more calcium is required.

You need a lab test to calculate a liming requirement. In short .... get a lab test.

so, I would check your pH and raise or lower it accordingly so that you get as close to a neutral aka 7 on the pH scale.

You don't need a neutral pH to grow turf. Anything in the range of ~ 5.0 - 8.4 will generally work for most turf ... where 6-7 is optimum.

A basic soil test kit there is about twenty dollars. It will give you the macro nutrients levels only.

Those kits are very inaccurate. Send an appropriate composite sample to a good lab.

Dr.NewEarth
04-11-2011, 11:22 PM
The organic method I recommended has worked fine for me.

Correct the pH and many of your lawn and garden problems will go away

The point was to get rid of the crab grass. What I suggested requires an "optimum pH."

The HD tests are a cost saving example.
That information can be used by other people too.

You do not always require an expensive lab test.

A lab test will typically cost you over a hundred dollars. In Vancouver they are $120 plus 12% tax.

I will not say any-thing else. Thanks and good luck with your crab grass problem.

Kiril
04-11-2011, 11:29 PM
The organic method I recommended has worked fine for me.

Correct the pH and many of your lawn and garden problems will go away

The point was to get rid of the crab grass. What I suggested requires an "optimum pH."

No offense, but I see crabgrass in soils that are hovering around neutral and are high in Ca. Don't play games with your soil, especially Ca .... get a lab test. In the states, you can get a soil lab tested (basic test) from $18-40.

You do not always require an expensive lab test.

You do if you want actionable information .... unless you have lab grade equipment at your disposal.

Smallaxe
04-12-2011, 07:21 AM
it doesn't last 90 days more like 6 weeks that is why timing is so critical with CGM, if you are going after CG it should be applied as the soil temp is rising from 60 to 65

Thanks for indicating that timing is essential for CG application...

Here the snow is finally gone and we hit 70 degrees on Sunday, but rain/snow mix for later this week... The squirt and ferts will soon be out for !!! CG Prevention !!! in a few more days for CG that couldn't possibly germinate b4 Memorial Day... and likely closer to July 4th...

So I vote for your method of CG control w/CGM... :)

1506cmo18
04-18-2011, 07:36 PM
for KBG 3 weeks before or 3 weeks after seeding

What does KBG stand for?

The snow is just melted and I'm looking for a good product to spread on my lawns that need nutrients and a weed protection. Is corn glutten meal a good option?

I'm also looking at spraying weeds with a vinegar solution, picking them out then adding a new compost material and seed.

With the statement above, after spreading CGM i should wait 3 weeks to seed?

JFGauvreau
04-18-2011, 08:11 PM
What does KBG stand for?

The snow is just melted and I'm looking for a good product to spread on my lawns that need nutrients and a weed protection. Is corn glutten meal a good option?

I'm also looking at spraying weeds with a vinegar solution, picking them out then adding a new compost material and seed.

With the statement above, after spreading CGM i should wait 3 weeks to seed?

Kentucky Blue Grass.

Watch out when you spray vinegar on your weeds, since it will also kill the grass.

1506cmo18
04-18-2011, 08:16 PM
I'm also in Canada, how did you make out spreading CGM?

Do you still use it for nutrients?

1506cmo18
04-18-2011, 08:58 PM
After the vinegar is sprayed, do you guys remove the weeds and reseed?

JFGauvreau
04-19-2011, 08:26 AM
Ya just spread it like a normal fertilizer, or mix it with your fertilizer. However, like mention in the other posts, timing is crucial. It must be applied 4-6 weeks before the crabgrass seeds germinate in order to kill them.

CGM has I believe a 10% slow release nitrogen already in it. Nothing big.

Ya you can always put some compost and reseed the patches that killed the weeds with vinegar, however, if your gonna do that to each weeds in a 5,000sq/f lawn, you will find it quite slow lol

Smallaxe
04-19-2011, 09:43 AM
Ya just spread it like a normal fertilizer, or mix it with your fertilizer. However, like mention in the other posts, timing is crucial. It must be applied 4-6 weeks before the crabgrass seeds germinate in order to kill them.

CGM has I believe a 10% slow release nitrogen already in it. Nothing big.

Ya you can always put some compost and reseed the patches that killed the weeds with vinegar, however, if your gonna do that to each weeds in a 5,000sq/f lawn, you will find it quite slow lol

Didn't Bill say you can overseed in 6 weeks?
... "it doesn't last 90 days more like 6 weeks that is why timing is so critical with CGM, if you are going after CG it should be applied as the soil temp is rising from 60 to 65 "

Now you're saying 4-6 weeks b4 it will begin to work? So can I sow my KBG right along with the CGM as long as it germinates and grows some within th 4 week period?

It is this kind of real world experience that makes it sound more like snake oil, all the time... :)

JFGauvreau
04-19-2011, 09:52 AM
Yes, put down CGM 4-6 weeks before the time the seeds germinate. If you put it 2 late, the CGM will not have any effect and the crag grass seeds will germinate.

And if you put down KBG at the same time of CGM, i'm not sure if it will work lol, since KGB takes 14-28 days to germinate, sometimes even longer depending on the soil temp. Maybe rye grass or fescue will be able to grow faster before the CGM has any effect.

1506cmo18
04-22-2011, 05:35 PM
Ya just spread it like a normal fertilizer, or mix it with your fertilizer. However, like mention in the other posts, timing is crucial. It must be applied 4-6 weeks before the crabgrass seeds germinate in order to kill them.

CGM has I believe a 10% slow release nitrogen already in it. Nothing big.

Ya you can always put some compost and reseed the patches that killed the weeds with vinegar, however, if your gonna do that to each weeds in a 5,000sq/f lawn, you will find it quite slow lol

So once the vinegar is on the weed, will it kill it right down to the route?

or should I spray with vinegar then dig it up and spread soil and seed over top?

phasthound
04-22-2011, 06:00 PM
So once the vinegar is on the weed, will it kill it right down to the route?

or should I spray with vinegar then dig it up and spread soil and seed over top?

Vinegar will not trans-locate into the root and kill the plant. It burns the foliage and interrupts photosynthesis. Several applications are required. Household vinegar will not do the trick, you need 20% vinegar. If you splash this stuff in your eye, you will have permanent eye damage. If you're willing to dig out the weeds, then get to work doing that, skip the vinegar.

Five Points
04-23-2011, 08:18 AM
The CGM is about 9 or 10 per cent, but the rate is like 20 lbs producct per thousand. Adds up to quite a bit of actual N per thousand doesnt it. Would you really want to add more fert to it. I am interested in comments on how well this works as for greening up the turf in the spring.

Thanks

ICT Bill
04-23-2011, 11:46 AM
The CGM is about 9 or 10 per cent, but the rate is like 20 lbs producct per thousand. Adds up to quite a bit of actual N per thousand doesnt it. Would you really want to add more fert to it. I am interested in comments on how well this works as for greening up the turf in the spring.

Thanks

2 pounds of N per 1000, OH YEAH! it will green it up alright, I hope you like to mow

Smallaxe
04-24-2011, 09:17 AM
So if I were to use this stuff for lawns, I would have my dormant seed in place or soon afte the ground is thawed, Say about: Early March, ready for it to germinate when it warms up enough. Maybe late April-Late May, depending on th weather...

Now, if the soil isn't warm enough to germinate KBG, by late May I really can't expect CG to pop until late June maybe July on this particular lawn... So possibly putting the stuff down in Mid May so its working by mid-late June is the best way to go...

Not a bad time to fertilize also, since we know that early Spring causes thatch and shallow roots...

Now the big question, When do CG germinate in your area, and how can you time it???

When the forsythia blooms... :laugh: