View Full Version : Pre-m's: CGM vs. Weed and Feed - plz enlighten me.

10-07-2008, 12:45 PM
Before I go on with my questions, I understand this may seem to some veterens like a very vague and broad question.

Just for the record I used CGM on my best properties this year and it worked very well despite its high cost. From what I understand, cgm prevents new seedlings from forming a root. Is this how all pre emergents work? Is cgm even a pre emergent or should it be considered to be a root pruner?

Which brings me to my next round of questions, what are the ingrediants in weed n feed that act as the pre emergent and how does it work?

Are either of these products similiar to Preen's garden pre emergent from those little shaker containers in garden centers?

10-07-2008, 02:46 PM
It was found that a byproduct of the corn (Zea mays L.) wet-milling process, corn gluten meal, has potential as a natural preemergence herbicide. U.S. Patent 5,030,268 on the use of corn gluten meal as a natural herbicide was issued in 1991. The patent was reissued in 1993 with broader claims that cover the use of corn gluten meal on field crops and home gardens. Two additional patents were also issued in 1993 on the technology. The first is on the use of hydrolyzed proteins from corn and other grains that were shown to have higher levels of herbicidal activity than the corn gluten meal. These materials are water soluble and can be sprayed on the soils surface. The second patent was on 5 dipeptides extracted from the hydrolyzed corn gluten meal. These dipeptides were shown to have the same type of biological activity observed when the corn gluten meal and the hydrolyzed meal are applied to the soil.

List of seven Pre-emergent chemicals by their Brand Names:
Dimension..... Gallery.....Pennant
Pendulum...... Surflan..... Snapshot

the preen is, A,A,A-TRIFLUORO-2,6-DINITRO-N N-DIPROPYL-P-TOLUIDINE. does this help you any, or do I need to point you to the google button????

oh almost for got to type in the 35 pages of efficacy,LOLOLOL

10-07-2008, 02:49 PM

Pre-emergants can work differently. I haven't researched them specifically and you might get more details if you ask this in the pesticide forum but here is a basic answer.

As you should know, each pesticide has a different mode of action (way it kills the plant).

One pesticide might contain a blocking enzyme that tells cells not to make chlorophyll. The plant then runs out of chlorophyll which means no photosynthesis, which eventually kills the plant.

Another one might be a chemical or enzyme that tells the plant it is time to grow, grow fast, and keep growing faster. This one makes the plant outgrow itself and die.

Another (like vinegar) might dissolve the cuticle layer on a leaf and stop the plants ability to retain moisture.. and the plant eventually dehydrates.

Pre-emergents have different modes of action as well.

Tenacity stops the plants ability to make chlorophyll so the plant dies.. the reason it is a pre and post emergent is because it will stay in the soil (this particular pesticide does not have a very long soil residual) and the sprouting plants can absorb it and die.

Other pre-emergents might contain something (chemical, hormone, enzyme, etc) that 'tells' the seed not to germinate at all.

And other ones might actually kill the seed.

What is the mode of action in Preen? Not sure... wiki the active ingredient to find out...

What is the mode of action in Corn Gluten Meal? Apparently something to do with keeping seedling roots from developing.. it would still be a pre-emergent.. but its mode of action might be some sort of root pruning... make sense?

What about the weed and feed? It depends on what pre-emergent it has.. research the active ingredient to learn how each works...

Now to prevent 'super weeds' it is important to rotate through the products mode of action. Lets say you always treat with CGM... well eventually there is a morphed seed that doesn't respond to CGM and sprouts anyway. It produces more plants that are all immune to CGM and CGM is now no longer effective...

But if you change the mode of action every year... one year the dandelion makes it past the CGM.. the next your its 'children' which are also immune to CGM will die because you used dimension instead of CGM. Now they can't pass the CGM immunity trait on because they are dead.

Weeds will never build an immunity to mechanical controls... (hand pulling)

So they can work differently yes...

10-07-2008, 06:41 PM
The only mode of action that I have found for pre-m is that it acts as a hormone that inhibits root growth at germination.

I discovered that after hours of searching and it did not discuss CGM. I should have saved that site, but I did not. If you find a good site that explains how certain chemicals function and WHY, save it and pass it on plz. :)

10-07-2008, 07:03 PM
While not labeled for turf yet and a shorter residual than most pre-emergants... Tenacity is a pre-emergent with a different mode of action (bleaching)...

Also.. if it inhibits root growth in a different way than another it may be a different mode of action, did you look into how each inhibits root growth Smallaxe? that would be nice to know.

Ditto about finding an article... I would love to get it if anyone finds one. :)

10-07-2008, 07:53 PM

see if this helps any

10-07-2008, 10:34 PM
Firstly, Thank you for the facts. Now I know, among other things, the "mode of action" is one of the main terms I have been looking for in order to research the subject further.

JD brings up a good point in that CGM uses up the seeds because they must germinate before they die. Hence, the weed populations will effectively be depleted due to mainly to this fact. This is one of the main reasons I started using the product.

Wouldn't a "kill the seed" or "root pruning" mode of action be key to sustainability?

My customers want a perfect lawn by that is cared for with environmentally friendly practices. Their priorities though go in that order. My professors are split down the middle. Some are hardcore in organic horticultural practices and some utilize both organic products , synthetic products, and sustainable practices to help acheive sustainability in the landscape.

It seems like trying to be a completly organic company would also mean that I would never be able to solve people's short term turf issues.

If I use chemicals as responsibily as possible (I feel guilty any time I use weed b gone), remove the population of weeds and the seeds they will inevidebly spread in the future, and use pre emergents, like cgm, to stop the new ones I could, (theoretically) stop my weeds...

(everyone's like ya TMG, Duh)

If I use hybrid methods to "fix" short term issues then use organic products to maintain a lawn, isn't that like cleaning up my dirty foot prints in nature?

Maybe in the short term I may decrease or perhaps destroy microbe populations but if I re-inoculate the population with ct and microbe food then what's wrong with using chemicals in the short term...Like say cavalcade (weed and feed chemical) in a nutrients plus product (which are like 70% organic based) as a pre emergent. This product is like 10 times cheaper than cgm and prob more effective right away.

10-07-2008, 10:43 PM
I swear I have A.D.D. with forum discusions sometimes the way I switch up discusions like this. If I have to make a new thread to continue this one I will. :)

10-07-2008, 10:47 PM
Here is a link from a post in a thread started by Bill on earthworms.
In with the bad and out with the good.


it shows worms' ability to poop out the bad.

Here is the conversation for further reference...

If worms can clean out toxic waste I think they can clean up some lawns...

I was pondering the idea of using a synthetic pre emergent to save on my fertilizer bills next year. If I could get one that kills seeds or spends them like cgm. Then I could save my customers money. Couldn't I then follow up with an earth friendly mop of ct to replenish my microbial population.

10-07-2008, 10:51 PM
you are talking about a bridge product or hybrid system, great thing to do if you don't have the means or skill to do it all the way, it sounds like you are young and ready to learn more, that's the best thing that you can have! after that no you really don't need any weed and feed cross over, try and grow grass real well first and then we can talk about weeds, what the main Idea is, to out compete the weeds and make the grass growing conditions favorable and the weeds,,,, well no one is there friend, especially you.LOLOL.

all joking aside the weed program is the week point to every, even mine, organic lawn care program, coast into some of the old posts, mine and others, It can be done on your hands and knees hand weeding alone, but there also comes a time and place for the weed burner or the scythe/burn out, to get used in a spot spray, at the point that the lawn is 40% weeds why waist time and your clients money and not just add the compost and re sod/seed(as needed regionally), the yard and have a new lawn that is worth something.

10-07-2008, 10:56 PM
omg fertilizer what??? do you mean compost and horse sh*t or worm casts and compost tea??? yeah some on here will try and sometimes do sell composted something or another, but like almost any one will agree " compost does a soil good"

10-08-2008, 08:24 AM
TMG, I don't know how to counsel your conscience on using broadleaf killer or a functional pre-m in your goal to sustainability. But how about thinking of how 'sustainable' cgm is and the sources and amounts of resources need to produce synthetics. Its a horse a piece because neither is sustainable.

Another thought to keep in mind is perhaps, just maybe, this chicken little, fearmongering is a bunch of bs. Living sensibly and not trashing your environment is obviously the smart way to live.

What is the percentage of the atmosphere co2 up to now anyways? What was it b4?

Co2 is plant food. Lies and fearmongering is a constant of gov't propaganda and teachers and professors are trained to pass the crap along as fact.

Somehow throwing food on your lawn while people have to cut back on what they are able to afford to eat, seems sustaiable. :laugh: