My fiancé is an organic herb farmer whose main crop is sweet basil - he has over 4,000 bushes at the moment that he hand tends. We were advised last year to try a strong grade of vinegar to spray on Johnson grass to control it. He has no big problem with other weeds. Well, it's that time of year again when the rains, etc., have created a condition (field too wet to plow) where the Johnson grass is overwhelming and we want to pursue the tip for using vinegar that we were given last year via this Web site. (John Dromagle of Gardenville, I think was the source) The problem is we don't know what percent acidity vinegar to use, what kind, or where it can be obtained. Do you have any more information about using vinegar? Please advise. The farm is located about 8 miles West of Marble Falls.
I spoke with Malcolm Beck about his formulation of the product named Organic Weed Control. It is made from an acetic acid (99 percent) solution mixed at a one-half acetic acid to one-half feed-grade molasses. Regular vinegar is only 9 percent and will not be effective. If you could find a vinegar with 12 - 20 percent acetic acid content, you could use it undiluted mixed with enough feed-grade molasses to color the solution and obtain the same result as the 99 percent acetic acid product which is mixed half-and-half with feed-grade molasses before use. Remember that this product will solidify when temperatures go below 54 degrees F. but it is doubtful if the product would be used during such cold temperatures anyway. Gardenville sells the Organic Weed Killer for $14 per quart and $45 per gallon. Please realize this product is a contact, burn-back herbicide which will not kill the underground portion of the Johnson grass — so reuse is required after re-sprouting has occurred. A glyphosate herbicide such as Roundup, Ortho Kleanup or Finale are systemic (goes into the plant's system) and completely kills the Johnson grass. Glyphosate could be applied with a wick or rub-on applicator to the foliage only of the target plant and not damage surrounding vegetation or be up taken into adjoining plant material. Gardenville sells these wick applicators for use with the glyphosate herbicides. The glyphosate herbicide would be cheaper and much more effective over the long run than would be the acetic acid herbicide. You decide what you want to use or maybe do test blocks for the sake of comparison.