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Green Industry News MAY 2019

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Navigating the Glyphosate Dilemma 

Man spraying herbicide on plants
Glyphosate is the active ingredient in the herbicide, commonly known as; Roundup. This is an herbicide that we in the Green Industry have come to depend upon quite heavily. Unless you have been living under a rock; totally avoiding social media; or ignoring the news you should be aware of the controversies surrounding this product.
You’ve probably already had questions about its safety or have been confronted about using the product. In fact, we as Cooperative Extension Agents have already been confronted with the question of why we still recommend its use. Our answer: “Our role as faculty in the Land Grant University System is to continue providing non-biased, research-based information to clients, and until the research is clear that this product causes cancer at the label rates and following the labeled directions for reducing exposure then it remains safe.”
Our campus-based weed scientist; Dr Joe Neal shared the following information just this week:

On April 30, 2019, the EPA announced the availability of the proposed registration review decision for glyphosate. From the report: ” Today, the U.S. Environmental Protection Agency (EPA) is taking an important step in the agency’s review of glyphosate. As part of this action, EPA continues to find that there are no risks to public health when glyphosate is used in accordance with its current label and that glyphosate is not a carcinogen. The agency’s scientific findings on human health risk are consistent with the conclusions of science reviews by many other countries and other federal agencies.”

Regardless of the validity of all of the research, the controversy will continue to persist. You will likely have clients that want you to use alternatives and yes there are some available. Many are not safer and often the alternatives are actually more hazardous to you as the applicator and the environment, so understand the facts.

One that gets touted frequently on social media as a great all-natural weed killer, simply put, is not. The basic recipe is vinegar, epsom salt or table salt (both versions are used) and Dawn dish soap. Using this mixture as a licensed pesticide applicator on your client’s property is illegal. However, your clients can use as much as they care to.
The efficacy of horticulture vinegar-based herbicides tends to be low, the cocktail described above not being much better. They are contact herbicides and will readily burn the foliage of new annual weeds that the product actually comes in contact with. They are not systemic so will do a poor job controlling perennial weeds or woody vegetation. Sure you can use them to give peace of mind to your clients but – be aware that you are going to need to make more frequent applications, encounter an increase in potential exposure, and reduce the soil pH of the site you’re using them on.
Here is a list of several alternative products and how they compare so you can be informed. In some cases you might find a mechanical method of weed control, such as the team method – pull, pull, pull or the Santa Claus method ho, ho, ho, to be the most friendly weed removal methods.

So, What’s in This Cocktail? 

Vinegar  – The grocery store version is 5% Acetic Acid and a pH of 3. If you purchased a legally labelled Horticulture Vinegar the Acetic Acid is 25-30% and will have a signal word of Warning. The signal word on Glyphosate products is still Caution. The PPE requirements of horticulture vinegar-based products are more extensive than Glyphosate. An LD 50 (the measurement of toxicity) is 3000 mg/kg 40% more that of Glyphosate which has a LD 50 of 5000 mg/kg. Vinegar is highly mobile and can move rapidly into the ground water, thus potentially causing contamination.
Epsom Salt  – Magnesium Sulfate, while a good compound of minerals that can be a beneficial tool for providing the secondary nutrient Magnesium; it can be toxic to plants at rates exceeding the recommended dosage.
Table Salt – Sodium Chloride, has been used for years to help with food preservation and seasoning. The chemistry at the proper amount can be a beneficial nutrient as it is a compound both in our blood and tears. If applied to soils it renders them useless for plant growth for indefinite periods of time. Salt can be an effective pre-emergent herbicide in an area that you don’t plan to grow plants in for a long, long time.
Dawn Dish Soap – This product contains so many ingredients that are known to be unhealthy that considering it to be remotely natural is ludicrous. (Sulfuric acid, Alky esters, Sodium salts, Amine oxides, Ethanol, and Limonene, to name a few) The Ethanol ingredient at 5% indicates a 50 million PPB (parts per Billion) content of a known Carcinogen- not probable, not possible, not perceived, but absolutely known. For reference table wine containing 16% Alcohol contains 160 million parts per billion of the same known carcinogen and nobody screams “poison”. Many of the ingredients of the dish detergent have LD 50s of <2000 mg/kg so making those ingredients at least 50% more toxic than the vinegar.
*LD 50 is a measurement of toxicity used by researchers to measure the amount of any product that is considered lethal if kills 50% of the population (of test animals) over a defined period of time. The measurements are in Milligrams/Kilograms of Mg/Kg. Products tested include pesticides, natural chemical compounds, specific elements, cleaning supplies, processed foods, and toiletries. The lower the LD 50 is the more toxic because it is indicating that it takes less of the material to kill the target by weight. As LD 50 only measures acute toxicity it isn’t necessarily a measurement of the potential for carcinogenic properties, nor does it measure potential for negative environmental impact.

More Helpful Resources

Vinegar and Epson Salt as Herbicides…

Misinformation, pseudoscience, and gardening myths are everywhere and are as stubborn as a thistle. One of those thistles is a concoction of household vinegar and Epsom salts can be effective in killing weeds. …

Read morelocal.extension.umn.edu


Homemade Herbicide (08-28-14) – Crop and Pest Report

From web sources, there appears to be a recipe for making your herbicide from common household products. Sources call it a “magical, natural, weed killing potion” with high “safety, effectiveness, and naturalness” and recommend as “an alternative…

Read more | ag.ndsu.edu