Food-Grade vs. Pool-Grade Diatomaceous Earth (D.E.)
Recently, an industry associate and I were discussing diatomaceous earth. That got me thinking about a call I received a couple weeks ago from a person who had concerns about using it. Many folks are confused by the different types of diatomaceous earth, so that's what this week's tip is about.
For pest control, the only type of diatomaceous earth you should use is "food-grade." "Pool-grade" diatomaceous earth has been chemically processed and is carcinogenic, but the food-grade version is certified by the Organic Materials Review Institute (OMRI) and is considered safe by the FDA for use indoors and out. Food-grade DE essentially shreds an insect's body, and they desiccate (shrivel up and die).
But there's a downside: Only a little moisture, like morning dew, ruins its effectiveness. So, for long-term control it has to be applied frequently.
DE isn't really an "earth" product to me. It's the fossilized remains of microscopic shells created by one-celled plants called "diatoms." Not all deposits of diatomaceous earth, or the diatoms in those deposits, are the same. And that can make a huge difference in its quality and the uses for which it's best suited.
There are two basic types of diatom deposits — fresh- and salt-water deposits. They can contain different types of diatoms or a mix of them. Not all shapes are effective, and some deposits contain undesirable unsafely concentrated sediment.
Both "swimming pool" grade and natural diatomaceous earth come from the same fossil strata, but they are processed differently. Natural DE such as Soil Mender Diatomaceous Earth is mined, dried, ground, sifted and bagged. Swimming pool DE is heat-treated (calcined), partially melted, and chemically treated. As a result, the heat-treated DE contains a large percentage of hazardous crystalline silica. The World Health Organization confirms that a crystalline content of 3 percent or more is hazardous to your health and to the health of your animals. The insecticidal-grade diatomaceous earth has less than .5 percent crystalline silica.
Some DE deposits contain a large percentage of clay and are therefore less effective as an anti-caking agent. Salt-water diatoms are inconsistent in shape and more fragile, making them less effective. And those deposits are often compromised in purity due to tidal variations. So, when you look for DE at lawn and garden stores, make sure it says "food grade" or "OMRI certified" (a 100 percent organic certification).
DE insecticides are a safe way to rid your home of roaches, silverfish, fleas, scorpions, spiders, ants, flies, etc. You name it, and DE will take care of it. DE dusted on the lawn for fleas and ticks will protect your pets and you. You can also dust your pet's fur and bedding with DE - it is that safe!
F.M. 359 at F.M. 723, Richmond
The final GardenLine Appearance for 2010 is this Saturday. We've got plenty slated for 2011, but they don't start up again until February. So, if you can wait that long to get a Lemmonhead shirt, or to get your garden question answered by me, or to get your hands on some free GardenLine goodies, then by all means wait.
But if you can't delay, come see me 11 a.m.-1 p.m at Enchanted Gardens.
If you bring in a canned item for their food drive, they will give you a free cyclamen plant. Plus, my friends at Nitro-Phos are cleaning out their warehouse, so that means you can walk away with all kinds of free goodies. If you want to know how lucrative a warehouse cleaning can be, just ask anyone who stood in line to talk to me at RCW two weekends ago!
It's also appropriate that this e-mail tip is about DE, since the best form of it comes from Soil Menders. Their guy, Mike, will be on hand to give out free product and answer any DE questions.
Also, Enchanted Gardens has fresh Christmas trees, garland and poinsettias at exceptional savings, along with great gifts for the gardener in your family.
And since this is the last GardenLine appearance this year, you don't even have to bring the usual copy of this e-mail to qualify for freebies. Just show up!
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