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View Full Version : How much "soap" to add to herbicide




atp500
07-16-2009, 09:30 AM
I have heard that if you add a little liquid dish soap to your sprayer, that the herbicide sticks better to the weeds. If so, i am wondering if there is a formula for the amount to use. I have a 14 gallon pull behind sprayer for my quad.
Any help is appreciated.
Thanks
Ken




fairfax1
07-16-2009, 09:53 AM
You see the recommendation of soap as a surfactant ('Dawn' is frequently mentioned) often enough on internet forums...be they habitat or garden forums.

One of the problems with that suggestion is that the rocking and sloshing of whatever tank you use will create a sudsing problem....which, in turn, makes the tank more difficult to clean.

Surfactants specifically intended as an adjuvant to herbicides shouldn't give you that problem....plus, they are specifically designed to be compatible with herbicides.

I have used Dawn dishsoap and it didn't seem to hurt anything....leastwise I couldn't really tell if it hurt the effectiveness of the glypho I sprayed...or, whether it helped. I've also used low-sudsing Tide laundry soap. Again, it's hard to tell the difference if you don't intentionally do a side-by-side comparison of with and without.

I now use a dedicated herbicide surfactant.....just to be sure.

Mightymouse
07-16-2009, 01:15 PM
I have heard that if you add a little liquid dish soap to your sprayer, that the herbicide sticks better to the weeds. If so, i am wondering if there is a formula for the amount to use. I have a 14 gallon pull behind sprayer for my quad.
Any help is appreciated.
Thanks
Ken

I'm pretty sure the soap won't help the herbicide stick to the plant. The soap is a substitute instead of using a Surfractant. From what I've read surfractant's soften up the plant and help the herbicide be absorbed more quickly and completely which provides a faster and more complete kill.

You can buy gallon jugs of Top Surf at TSC for cheap, like 13.00 if I remember right.

Theonlydoe
07-16-2009, 01:32 PM
As stated crop oil concentrates and Non-ionic surfactants are the best surfactants. That is what they are made for, that is why farmers use them...With that being said you can use dish soap as a surfactant. I understand that Dawn is the most recommended. If you do the math though it figures out to be more expensive in the long run.

Recommended amounts are:

1/4 cup/gallon of mixture

10 cups/ 100 gallons of mixture

The average size bottle of Dawn dish soap is 24 oz. or 3 cups

fairfax1
07-16-2009, 02:48 PM
This soap technique...and surfactants in general....don't make the solution "stick' to the plant. Instead, they relax the surface tension of water which, in effect, makes water wetter.....thus better able to be absorbed by the cells of the plant.

You've seen water drops on a table, of course. What makes them half-round or globular is the tension on the surface of the water. With a surfactant that tension is gone and the water will not form droplets.....it will instead flow in a sheet-like manner. That's the 'wetter' water concept.

Mightymouse
07-16-2009, 03:07 PM
This soap technique...and surfactants in general....don't make the solution "stick' to the plant. Instead, they relax the surface tension of water which, in effect, makes water wetter.....thus better able to be absorbed by the cells of the plant.


Well, I was half right at least!!! :lol:

Anderson
07-16-2009, 05:23 PM
I agree with Fairfax. The only thing I would add is most surfactants are used @ 1qt/100 gallons of spray solution. I have used Dawn and also liquid laundry soap but do like the commercial products better. The soaps work in a pinch, 4-5 oz in your 14 gallon sprayer is adequate.

Tim

atp500
07-16-2009, 05:46 PM
Thanks Guys, That is what I needed and I appreciate the knowledge from all of you.
Ken