Spray Away Weeds

Q. Mike: Because of all the rain this year I am spending more time on weeds (which I hate!) than my garden. I am not happy! I was going to purchase "Weed Aside" from Gardens Alive, but they say it does not kill the roots of weeds. What good is it then?
            ---Dena in Long Beach, CA

A.    Hey, count your blessings—weeds are always worst during the best gardening seasons. I have also had lots of rain in my area—and lots of sun. As a result, pollen counts are at record levels; but so is our raspberry harvest. The weeds are as high as an elephant's eye—but so are my tomatoes and cukes. I'll take it!

The best way to control weeds is to prevent them: Mulch early and often with an inch or two of non-wood organic matter, like compost, pine straw, shredded leaves or peanut or cocoa bean shells.  (NEVER use wood chips, 'premium triple shredded bark', dyed mulch or licorice or other root mulches anywhere near your home, car or wanted plants. See "Is your mulch miserable?" for details.)

Soap-based herbicides like "Weed Aside" are very effective for spot control. Like insecticidal soap (which is processed differently), these sprays kill weeds by smothering them with a soapy film. Yes, the label and advertising wording on some of these natural products can be confusing; its really not 'their' fault—they have to dance around a lot more federal and local regulations than nasty chemical herbicides (Boo! Hiss!). The Bottom Line? One good soaking soap spray at the peak of a hot, dry sunny day will kill just about any annual weed. Perennial weeds with big tap roots will need repeated applications, but if you keep smothering their new growth, it will starve the root and destroy the entire plant.

Q. I caught my new next-door neighbor spraying "Ortho Complete Vegetation Killer" on Bermuda grass along our common fence line—where my dog lies down to wait for me to come home from work. I know he'll do this again unless I take care of the Bermuda grass myself. What can I use that's safe?

---Cynthia in Las Vegas

Mike: You have often mentioned high concentration vinegar products that can be used to spray tough weeds instead of Roundup. Where can I find them?

---Judy Lynnin Philadelphia

A. Well, I USED to call them high-strength vinegar herbicides. But virtually all of these products have changed recently—many so dramatically they no longer contain vinegar! (And several are now approved for use in organic agriculture.)

Here's a sampling of what's currently available in the rapidly growing world of chemical herbicide alternatives. As with soap sprays, all of these products work best when applied to plants in hot, sunny weather. Don't spray them on wet, cold plants or if it's about to rain; you don't want to dilute the stress you're inducing.  

The declared active ingredient in "Burn Out II" from St. Gabriel Laboratories is clove oil (12% in the concentrate; 4% in the Ready to Use form); apparently, any essential oil will burn foliage, and clove is the oil of choice. It also contains vinegar (8% & 3%) and citric acid as so-called 'inert' ingredients, but both are actually potent herbicides as well. Another St. Gabe product, "Poison ivy defoliant", marketed for tougher weeds, is simply the concentrate designed to be used full-strength. You'll find these on store shelves nation wide (they have the best retail distribution of any the products we're about tomention) and they're sold direct. But their 'vinegar' is chemically derived acetic acid; and sodium laurel sulfate is used as a surfactant (an ingredient that helps sprays adhere to their target); neither is approved for use in organic growing.  

Greenergy is phasing out their old West Coast product "Blackberry & Brush Block", and replacing it with "Brush, Weed and Grass Herbicide for organic production". Listed by OMRI (the Organic Materials Review Institute) and thus approved for certified organic growing, it's 20% citric acid and 4% vinegar (both naturally derived) with a soy-based surfactant; available in stores in many Western states and direct from Greenergy.

Garden-Ville sells "20% horticultural vinegar" in stores in the San Antonio and Austin areas, and via mail order. A new entry to the market (new to ME, anyway), Bradfield Organics in Springfield, MO markets an OMRI listed/organic approved 20% horticultural vinegar with ayucca-based surfactant. Rodhe's in Garland, Texas no longer carries their 20% vinegar; they now offer a grain-based 8% acidity vinegar—still under the original Green sense label. And "Matran 2" is an OMRI listed/organic approved product that's a whopping 33.7% percent clove oil alone. (God only knows what was in "Matran 1"…)

Back to vinegar/acetic acid: Charlie Goodman, Quality Systems Manager for 'Mizkan Americas', one of the largest vinegar makers in the US, explains that there are essentially four types of "acetic acid" and/or vinegar (the terms are often used interchangeably). One is synthetically derived (the photographic field uses a lot of acetic acid in film developing formulas and the like); and three are brewed from natural ingredients: "White distilled vinegar" is made from grain and ranges in acidity from 13 to 15% at the time of manufacture; wine vinegar's natural acidity is 10 to 12%, and cider vinegar comes out of the keg at 6 to 7%. Water is added to make table strength (generally 5%) vinegars, or they're concentrated to make things like the 20% variety.  

(In a wonderfully informative Bulletin ) , North Dakota State University Weed Specialist Richard Zollinger reports that vinegars ranging in strength from 5 to 20% kill a great number of different weeds very efficiently. So efficiently, in fact, that he compares the mechanism of action to that of Paraquat ("rapid dissolution of cell membrane integrity resulting in desiccation of foliar tissues, and plant death").

But, he adds that unlike that notorious chemical herbicide, "Acetic acid is not reported to accumulate in the environment, and readily breaks down into water." Of course, as with any herbicide, he notes that, "it is important to follow all directions and safety procedures.Vinegar with acetic acid concentrations greater than 5 percent should be handled with appropriate precautions."  He further warns that Acetic acid is non-selective; be careful to spray it only on weeds, and not wanted plants.  Charlie from Mizkan adds a concrete caution; don't spray vinegars on 'concrete', 'cement' or any other such surface whose manufacture involves limestone; vinegar can damage those surfaces. (Herbicidal soap sprays, however, are perfectly safe for controlling weeds in concrete walkways and the like.)

So take a close look at the various products we've described—and the many others that are doubtless out there—and choose the one whose ingredients you prefer or that's available locally. Just search the product and/or company name for more info on the individual products and their availability.

Yes, obtaining some of these products may require a slight bit of extra effort on your part. On the other hand, it's time well spent, considering that:
•    Recent research has found Round up to be deadly to frogs and toads and to negatively affect human reproductive function.
•    2, 4-D, the other most common American herbicide,is linked to non-Hodgkins lymphoma.
•    And a recent Scottish study found that use of any pesticide increases the risk of developing Parkinson's.

(You'll find more information on some of these studies in the "Mike's Tips" section at our YBYG website: https://www.wlvt.org/television/you-bet-your-garden/).