NATURAL or GREEN
HERBICIDES - THE HIDDEN FACTS

This article arose from a question from a customer that wanted to spray out a whole paddock – grass and weeds - but wanted a natural herbicide solution as they had a horse that was sensitive to chemicals. Fair enough.

We have always been keen on offering some more “green” herbicide alternatives but our criteria are quite simple.

•      They must work

•      They need to be reasonably cost- effective 

•      They need to be genuinely not harmful

 The reason we haven’t done it to date is that we couldn’t find one. So I put my Sherlock Holmes hat on and did a bit more research and here are some facts.

Before I move onto the so called “natural” and “green” alternatives let’s put up our Glyphosate 540 as a test product.

 

RAINBOW & BROWN GLYPHOSATE 540 

This has to bear the HSNO 9.1B toxic to the aquatic environment symbol. Basically don’t let it go into streams or lakes. You would have to be a bloody idiot to do this anyway.

 

GHS (HSNO code):

• Hazardous to Aquatic Environment – Chronic Category 2 (the old HSNO 9.1B)

FATTY ACID BASED HERBICIDES*

 

Promoted by the marketing guys as being natural solutions or “organic weed killers” and “less toxic than table salt” and other fancy marketing phrases to make you feel like you are keeping your kids, pets and the environment safe. Yep they come from a natural product. Although the fatty acids used can be derived from many plants the most common one these days is Palm oil and this is being hammered by the environmentalists because of the native deforestation to allow for planting of palm. Another case of not understanding the unintended consequences.

 

So, using the GHS codes the warnings above are:

 

•      Flammable Liquids – Category 3 (the old HSNO 3.1C -Moderately flammable liquid)

•      Skin Irritation – Category 2 (the old HSNO 6.3A -Skin irritation)

•      Eye Irritation – Category 2 the old HSNO 6.4A -Eye irritation)

•      Skin Sensitisation – Category 1 (the old HSNO 6.5B -Skin sensitisation)

•      Serious Eye Damage – Category 1 (the old HSNO 8.3A -Causes serious eye damage)

•     Hazardous to Aquatic Environment – Chronic Category 2 (the old HSNO 9.1B)

VINEGAR PRODUCTS

 

A popular home remedy but marketed as natural and green products by a number of companies. One well-known company is marketing a blend of vinegar and citric acid as a “bio-herbicide” because it is made using natural vinegar. The hazard ratings are based on this product but 10% acetic acid strength vinegars are much the same.

•      Acute Toxicity – Category 5 (the old HSNO 6.1E -Acute toxicity oral, acute toxicity dermal)

•      Specific Target Organ Toxicity (Repeated Exposure) – Category 2 (the old HSNO 6.9B -Specific target organ toxicity – repeated exposure)

•      Corrosive to Metals Category 1 (the old HSNO 8.1A -Corrosive to metal) 

•     Skin Corrosion – Category 1C (the old HSNO 8.2C -Corrosive to dermal tissue) 

•     Serious Eye Damage – Category 1 (the old HSNO 8.3A -Eye corrosive – corrosive to ocular tissue)

•      Hazardous to Aquatic Environment – Chronic Category 4 (the old HSNO 9.1D -slightly harmful to the aquatic environment

•      9.3C (substance harmful to terrestrial vertebrates)

 

Really only suitable for spot spraying and it acts by burning the weeds/grass so is acting as a contact herbicide. This means it doesn’t translocate into the roots so won’t kill the roots. Many cheaper white vinegars are just diluted acetic acid and not naturally fermented but to be effective you really need to be using a 10% strength. Normal household vinegar is around 4%. A very expensive solution and especially at 10% not really that safe either.

SALT (common salt or sodium chloride)  

It is not usually used on its own, but it is often used in conjunction with vinegar-based approaches. I have thrown this in to help put everything in perspective. 

•     Acute Toxicity – Category 5 (the old HSNO 6.1E – Acute toxicity oral)

•      Eye Irritation – Category 2 (the old HSNO 6.4A -Eye irritation)

Everyone wants to be gentle on the environment. It is not just the domain of the ardent greenies and all things being even close to equal we would use products that are more gentle on the environment and less toxic for us and our families but things are not always as they seem!!!

* based on two well-known, popular and heavily advertised brands.