Homemade Agralawn Crabgrass Killer?

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cjac9chris
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Homemade Agralawn Crabgrass Killer?

Post by cjac9chris » March 15th, 2021, 11:20 am

I had a serious crabgrass infestation last year in my backyard because I'd neglected my lawn for 4 years prior.

This year I put down pre-emergent (not organic... I know...) but I still have some crabgrass popping up.

I picked up Agralawn Crabgrass Killer the other day and it's doing a great job! Really smokes the stuff.

I'm pretty sure it's primarily baking soda and cinnamon with yellow dye added that turns yellow when it's wet so you know that it's activated.

If so, this stuff is crazy expensive for what it is! It's $10/lb.

Does anyone have a homemade recipe for making your own? Is the cinnamon even necessary?

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MorpheusPA
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Re: Homemade Agralawn Crabgrass Killer?

Post by MorpheusPA » March 15th, 2021, 5:54 pm

The exact list of contents are, "Cinnamon Bark, Corn Flour, Wheat Flour, Sodium Hydrogen Bicarbonate, Cumin, Yellow #5, and Red #40." Most of these don't bother me in the slightest. The cinnamon is probably the active ingredient. By the time we hit yellow #5 and red #40, we're at minor amounts (I use these myself in soap making and only tiny amounts are ever required for even very dense coloration). Corn and wheat flour are used as the carrier.

Could you make this yourself? Sure, just source those ingredients. Sodium hydrogen bicarbonate looks like a weird misprint because sodium hydrogen carbonate is baking soda. Sodium bicarbonate is baking soda. Sodium hydrogen bicarbonate would carry a positive charge.

The exact amounts are unknown and you'd have to play around to find them. My guess is that there's a lot of cinnamon bark (it probably stinks of cinnamon). And yes, cinnamon bark kills actively growing crabgrass. The corn and wheat are there to hold it to the plant and thin it out a bit. The baking soda is toxic to the plant (and the soil, so I might be inclined to try it without that, although it's a minor thing and I doubt it's more than ten percent of this mix, or less).

I have no idea why the cumin is there, actually. :-) And the colorant is to make it an attractive bright yellow with orange overtones so you can see what you did.

I can tell you that cinnamon bark runs $7-8 pound for small amounts. You might be able to source it cheaper through someplace like Essential Depot or the like, though. You'll need to grind it very, very fine and store in a tight jar to avoid losing the chemicals into the air.

cjac9chris
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Re: Homemade Agralawn Crabgrass Killer?

Post by cjac9chris » March 16th, 2021, 10:15 am

Well that settles it. If cinnamon bark is $7-8/lb., I'll just keep using this stuff. It works and is safe for my dog!

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Dchall_San_Antonio
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Re: Homemade Agralawn Crabgrass Killer?

Post by Dchall_San_Antonio » March 28th, 2021, 3:11 pm

Cinnamon is a MacGuffin. On the label they claim it is the active ingredient; however, about the time the first baking soda crabgrass killer came out, the University of FL recommended it to kill crabgrass in St Augustine lawns. Not long after, the same company selling the baking soda product took it off the market and replaced it with the cinnamon product still out today. This was a big topic on the Texas organic radio shows back in 2008. We talked about it here in this forum and at GardenWeb.

There is a trick to using it because baking soda will blow off of the weed unless it is wet. And crabgrass is hydrophobic. So the trick is to spray the crabgrass with a wetting agent first, then dust straight baking soda on to it very evenly. Both sugar and soap are decent wetting agents. I use a mix of shampoo and molasses at whatever rate works. Something on the order of 1 T of each to a quart of water is a good place to start. If the water beads up on the crabgrass, then add more soap and molasses until it flows and does not bead. Then you're ready for the soda. The best way to apply evenly is to sift it on, and the best way to control the sifting is to put the baking soda into a fabric like a sock or a Nylon stocking. The baking soda will stay in the sock until you squeeze it, and that will release a very fine powder. DO NOT BREATH and DO NOT GET IT IN YOUR EYES. The effects are painful and temporary, but emphasis on painful. Changing the pH of your tears is not recommended. Hold the sock at arms length on a wind free day and be ready to run if you see a cloud of dust rising up. I suppose wearing your Covid mask would help protect a little, but I've made the mistake once and will be much more cautious next time. Sealed goggles, like swimming goggles, would protect your eyes.

Here is a YouTube link illustrating how it works.

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MorpheusPA
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Re: Homemade Agralawn Crabgrass Killer?

Post by MorpheusPA » March 28th, 2021, 6:33 pm

Who knew? Well, that's easier, too.


cjac9chris
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Re: Homemade Agralawn Crabgrass Killer?

Post by cjac9chris » March 28th, 2021, 11:35 pm

Wow, that's awesome! Thanks, David!! I will start rolling my own once the bottle runs out.

Maybe this is a topic for another thread but this has me thinking... labor aside, is there an advantage to spraying weeds with a contact killer vs. pulling a weed (assuming you get the roots?)

The sprayed weed leaves a dead brown patch in your lawn but the soil is covered and undisturbed. The pulled weed leaves disturbed and uncovered soil which of course creates a perfect environment for yet another weed. Maybe I'm missing something though?

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Dchall_San_Antonio
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Re: Homemade Agralawn Crabgrass Killer?

Post by Dchall_San_Antonio » March 30th, 2021, 7:18 pm

Here is more information about using the AG product...which is virtually identical to just using baking soda. I don't have the full article but here's the abstract.
Glenn, Brian D., Barry J Brecke, J. Bryan Unruh, Jason A Ferrell, Kevin E Kenworthy, and Greg E MacDonald. "Evaluation of Alternative Herbicides for Southern Crabgrass (Digitaria ciliaris) Control in St. Augustinegrass" Weed technology 29, no. 3 (2015): 536-543. doi: 10.1614/WT-D-14-00094.1

Abstract
Southern crabgrass is a common turf grass weed throughout the United States, and in Florida a troublesome problem in St. Augustine grass lawns. Because of herbicide label changes and lack of herbicide tolerance, no POST herbicides are currently registered for homeowner use for crabgrass control in residential and commercial St. Augustine grass lawns. Alternative weed control methods, including cultural practices and unconventional herbicides, have been investigated to a limited extent for post emergence crabgrass control. In this study, alternative herbicides evaluated included 30% acetic acid, borax, sodium bicarbonate, and Garden Weasel AG Crabgrass Killer (sodium bicarbonate formulation including cinnamon, wheat and corn flour, and cumin). Treatments were applied to southern crabgrass at three growth stages (one to two leaf, three to four leaf, or one to two tiller). In the greenhouse, 30% acetic acid applied twice at 280 L ha⁻¹ and two rates of AG Crabgrass Killer at 976 or 1,465 kg ha⁻¹ provided ≥ 70% control of one to two–leaf southern crabgrass when evaluated 7 d after initial application (DAIA). No treatment provided > 70% control of three to four–leaf or one to two–tiller southern crabgrass or any size crabgrass beyond 7 DAIA. In field trials, no treatment provided acceptable (≥ 70%) southern crabgrass control at any weed stage. Initial turf injury was unacceptable for most rates of 30% acetic acid, sodium bicarbonate, and AG Crabgrass Killer, causing > 20% St. Augustine grass injury 7 DAIA. By 21 DAIA, turf injury levels had fallen to ≤ 20% for most treatments. Because of high turf grass injury and little residual control, alternative herbicides tested are not an effective substitute for using preemergence herbicides for southern crabgrass control. If other options are not available, they may have a role as a limited spot treatment in St. Augustine grass. Nomenclature: Acetic acid; southern crabgrass, Digitaria ciliaris (Retz.) Koel.; St. Augustine grass, Stenotaphrum secundatum (Walt.) Kuntze.
This is saying that these things work at a somewhat reduced expectation than might be in the marketing literature. Furthermore they might cause more damage to the lawn than advertised. Am I going to use baking soda? Hard YES to that. The article suggests that almost a month after application, the grass has almost recovered. For spot application on crabgrass or dallis grass, that's plenty good for my little lawn.

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MorpheusPA
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Re: Homemade Agralawn Crabgrass Killer?

Post by MorpheusPA » March 30th, 2021, 8:01 pm

Chemically speaking, it's a meh. The sodium will soil bind, but you're not using a huge amount. Sodium bicarbonate, all things considered, is rather alkaline overall (the sodium ion itself, once the -carbonate part reacts out [and it will with other things, eventually entering the atmosphere as carbon dioxide] is particularly alkaline).

In extreme (and I mean extreme) cases, you could sterilize a soil using this. But you can do that with table salt. It's called salting the soil by poisoning it with sodium. That's not really much concern in this instance.

Heavy use over a number of years might result in needing to apply some gypsum (calcium sulfate) to remove the sodium buildup. But we can do that if a soil test shows it's necessary, no problems. In a well-kept lawn, I can't see that it would be necessary from that alone; you'd literally have to be going through large boxes on small-ish lawns per year.

As I think on it, sodium carbonate, washing soda, would probably be even more effective, but might be harder on your grass (the pH is 11.6 versus bicarb's 8.4). It might be worth a try in one single spot for anybody that uses the stuff (I do, but I'm up north and don't get southern crabgrasses nor do I have St. Aug).

And for those with sodium lye on hand... I kid, I kid, don't play with that stuff. I have pounds, but with a pH of 14.0, you don't stick your hand in it nor scatter it around freely...ever.

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