Plants That Produce

 

Beer Is A Synthetic Pesticide

 

By Richard Frost

 

The word pesticide has a broad, often misunderstood meaning. As far as government regulations and product labeling are concerned, pesticide refers to any substance that is used to kill an animal, plant, viral, or fungal pest. So for example, a nursery cannot sell straight lemon juice for the purpose of killing weed seedlings or beer for the purpose of killing slugs unless the packaging has government-approved pesticide labeling. I doubt you’ll see that on beer anytime soon.

I sometimes receive enquires from people looking for a way to kill snails without using a pesticide. The intended meaning of course is a substance that is natural and somehow free of synthetic processes (e.g., ionic chemistry, distillation, purification, etc). Now some gardeners put beer out in trays or cans to attract and kill slugs at night. But you know, the production of beer involves those very processes and sometimes the same chemical salts that are used in the manufacture of pesticides and fertilizers. It is a contradiction to think that you are somehow living healthier by using beer to control slugs on your vegetables and herbs if you also drink beer -- not to mention wine or rum!

Iron phosphate is a naturally occurring mineral that is beneficial to plants and animals but deadly to snails and slugs. You can buy iron phosphate pellets under the brand name Sluggo at local nurseries or in bags marked pet safe snail pellets at big box stores. No one should worry about using iron phosphate to control snails and slugs. It is in most human vitamins, pet (mammal) vitamins, and plant fertilizers. My dog eats it when he’s bored from chasing lizards. If you buy a medium-large bag and follow directions, you’ll find that it doesn’t take very much and per application it is cheaper than beer. So there really is no good reason to use beer, unless perhaps you are out of iron phosphate.

This misunderstanding of chemicals and synthetic processes extends to fertilizer concentrates. I was at a garden shop a few weeks ago and observed someone walk past a bag of potassium nitrate and exclaim "I’d never use that! It is full of petrochemicals and salts!". In reality, potassium nitrate is a naturally occurring mineral that is mined out of the ground and hence, there are no petrochemicals. It is an ionic salt -- but it makes an acid with water and is beneficial to plants and organisms in the soil when applied at an appropriate dilution.

Did you know that organic fertilizers also deliver ionic salts to the soil and plants? The difference between organics and soluble concentrates is in application: the organic mixture is very low in concentration so you apply bulk amounts and it slowly releases the nutrient chemicals. Fertilizer concentrates are applied in very small dosages that are highly diluted in water. When applied properly, they do not kill soil organisms or leave behind salt residues. Further, the concentrates have a better balance of nutrients so that adding supplemental minerals is usually not needed. If you are worried about petrochemicals, then check the label: most water-solubles are free of petrochemicals. The only real difference is the price: the organic fertilizers cost around 4 times more per net pound of nutrients compared to the water soluble concentrates.

 

 

Reprinted with permission from October 2009 "Let's Talk Plants," the newsletter of the San Diego Horticultural Society, www.sdhortsoc.org

 

© 2009 San Diego Horticultural Society