HomeGuy" "Home wrote:
I mix concentrated Ortho Weed B Gon (Plus Grabgrass Control) with
water according to the label and use a 1-gallon handpump sprayer.

I suppose that it works, but I don't exactly see the spray "wetting"
the leaves and stems of the stuff I'm spraying. Looks more like most
of it beads up on the leaves and runs off.

I'm thinking that this stuff would be more effective if it "stuck" to
the leaves, and I think that's only going to happen if the surface
tension is reduced, possibly by pre-spraying the weeds with soapy
water, or alternatively maybe adding soap in with the weed killer and
water.

Does anyone have a clue regarding if the effectiveness of
water-soluble weed killer is increased if a surface-tension reducing
agent is used?

And just for clarity, Ortho Weed B Gon contains:

2,4-D (Dimethylamine salt)
Quinclorac
Dicamba (dimethlamine salt)

You could try adding a bit of liquid soap to the spray as you mix it and see if
it works better.