I was told here that I have to re-apply DE after it rains. That also means after I water. That proved to be a pain after many days and weeks of rain this year. I did not have any luck with it keeping off my cabbage worms. Other people like it though. And the pool store owner said the garden DE (triple the price or more!) is the same as the DE sold in pool stores.

Best way to use it is to wet your plants, sprinkle it on them and water only from below. Then you only have to reapply when it really does rain.

Pool filter DE is not the same as garden or food grade DE. The pool filter stuff is toxic and is not sharp like garden DE. It has been heated and has additives.

Ania

How about the plants already infested? (blackeyed peas)can I sprinkle it on the plants being dry?

Yes, you can sprinkle it dry, but it has more staying power when you put it on a moist plant.

I would spray the aphids off with the hose and then powder the plant with DE.

Ania

ants and aphids should be part of your garden along with the butterflies humming birds lizards snakes and toads. Unless something is causing a problem let it live. - Jim

Jim, I hate to kill anything, but they (ants and aphids) they got so bad they killed my zucs, hopefully I can save my blackeyed peas now and they were spreading into my corn. On the blackeyed peas blossoms aphips covered them and they would just dry up and die. I think I have it controlled now and the lady bugs can take over. It was major infestation but thanks to the DE looks like it under control now I hope, I was very careful with the lady bugs moving them to where the aphids weren't so bad when treating the other plants. By the way the DE is working great, only had alittle time b4 I had to go to work this morning but everything was looking alot better, hardly any ants.

the pool stuff is identical, and the only reason they tell you otherwise, is to justify the 3X price. otherwise why would you?

Pool grade DE is absolutely not the same as horticultural or food grade DE. It is processed in an entirely different way. Not only is it worthless in controlling critters, but is highly hazardous when inhaled. Pool grade DE typically contains as much as 65% free silica (cancer causing). The other products may have less than 3%.

DE doesn't dissolve when wet, so it doesn't have to be reapplied. But it will lose it's best potential as a pesticide until it dries out again.

Please don't use DE widely or indiscriminately. It's just as hazardous to beneficials as the pests.

so then i guess that whenever you swim in a pool with a DE filter, your risking cancer, aren't you? for its a fact alot of the DE ends up in the pool via the ports.

I've read that that the pool type & gardening type of diatomaceous earth are different. However, not knowing the difference at the time, I used the pool type DE in an apartment to get rid of pests that returned every month or two in spite of the Orkin man spraying several times. I was desperate & read about DE, so I sprinkled it on the floor along all of the basboards. I never saw any more pests after that.

I called the company that sold DE for gardens. They wouldnt comment on if it's the same as pool DE or if pool people used it. They remained 'neutral' throughout my questions but they tried hard to get me to buy thier product. You would think that their marketing and sales dept get plenty of these types of calls, enough to make atleast one small comment about the ingredients contained within and various usages they are well aware of if you're in the DE manufacturing industry. The other thing is that if they're manufacturing and distributing garden DE they are probably also distributing pool DE and many other chemicals related to that family of chemicals. In my opinion, They should know something!

I marched down to my pool store and showed the owner my sac of garden DE and he brought out a sac of pool DE to compare the ingredients. He recognized the listed chemicals and said they were the same and said many people use their pool DE for their garden.

Now........if he knows about gardeners using their pool DE for their garden, why wouldnt the garden DE company I called, make a comment to me about using their garden DE in my pool or using pool DE in my garden or any comment at all about any ingredients or warnings whatsoever.

The last line of the ingredients on the garden DE sac read, "other ingredients" whose overall percentage was very small. The pool DE sac listed its ingredients in full. They were identical, except for that tiny % of filler. The Garden DE people would not tell me what that little % was made of.

There was no warning on the pool DE sac that said 'do not use for gardens." The garden DE sac listed no warnings for other uses either.

Marial, they are different. The pool grade DE is heat treated, which causes it to become crystallized. It's this crystalization that causes the danger. Producers are supposed to list ingredients, as they both did (though I think they're not required to if the amounts are below a certain percentage, same as food), but they don't have to list production methods.

Diclemeg, swimming in it isn't what's bad ~ inhaling the crystaline form is what can cause cancer, just like inhaling asbestos.

From Wikipedia (emphasis and brackets [] are mine):

Safety considerations

The absorbent qualities of diatomite can result in a significant drying of the hands if handled without gloves. The flux-calcined form [pool grade] contains a highly crystalline form of silica, resulting in sharp edges. The sharpness of this version of the material makes it dangerous to breathe and a dust mask is recommended when working with it.

The type of hazard posed by inhalation depends on the form of the silica. Crystalline silica poses a serious inhalation hazard because it can cause silicosis. Amorphous silica [natural or garden grade] can cause dusty lungs, but does not carry the same degree of risk as crystalline silica. Natural or dried diatomite [garden grade] generally contains very low percentages of crystalline silica. Diatomite produced for pool filters is treated with high heat (calcining) and a fluxing agent (soda ash), causing the formerly amorphous silicon dioxide to assume its crystalline form.

In the United States, the crystalline silica content in the dusts is regulated by the Occupational Safety and Health Administration (OSHA), and there are guidelines for the maximum amounts allowable in the product and in the air near the breathing zone of workers.[6]

It was my understanding that pool grade DE was supposed to be labeled with some sort of danger warning. Maybe it varies state to state.

Thanks for jumping in with some good information, knittlin. I find it difficult to believe how little people seem to know this product.

You will always find a cautionary warning on any package of DE, whether it's pool grade, food grade, or horticultural grade. Inhalation of the airborne dust should be avoided, even with a very pure grade of DE. Airborne pool grade DE dust needs to be considered dangerous.

Isn't silica, sand ?

My understanding is that diatomaceous earth is silica sand. It is mined locally for use as a blasting agent. Home Depot sells it.

The sand is formed by long-since decomposed marine creatures that sink to the bottom of the ocean floor - and in places where the land has risen, it is mined - mainly as a use for blasting sand because of the sharp edges.

About ants - I doubt if anyone outside of California appreciates the invasion of ants that most of us have in summer.

In recent years, my yard has developed a new critter - lizards. I have no idea where they came from, but I seem to be seeing a lot fewer ants in the garden since they are becoming more numerous.

However, in the house, where ants congregate around the water, I spread cleanser with bleach - which will deter them - for awhile. If things really get out-of-hand, I use a spray - around the outside of the house foundation.

I gave up on corn - because ants seem highly addicted to it. Although I never tried diatomaceous earth either.

Good luck.

Bejay

Just my 2 c's.

knittlin, you're the 1st person to post what seems to be valid information on DE. To-date people would say it is not the same but couldnt post any back-up to validate their opinions so I just beleived what the pool store owner was telling me because of his wonderful reputation here in my region.

No wonder the pool DE didnt deter the cabbage worms or slugs when I tried using it around my brocolli.

Thanks!!

It's my understanding that the sharp edges of the silica slice up the insects causing death. So wouldn't the pool DE with more crystalline silica be more effective?

No Idea of pool grade compared to regular

But I am fully aware that silica is sand and yes it is extremly dangerous to breath in as particulate matter, I am in the sandblasting business it takes as little as three hours of heavy exposure such as blasting inside a tank to make deposits on your lungs

just be sure to wear a mask when handling

"Isn't silica, sand ?" No, not always, Diclemeg. But sand is silica. Just like beans are vegetables, but vegetables aren't always beans. Silica is a mineral that makes up sand, quartz, glass, and a myriad of other things in nature and out of it. Just plain silica is usually harmless, but crystalline silica isn't. Crystalline silica can cause silicosis (scarring of the lungs) and cancer.

"It's my understanding that the sharp edges of the silica slice up the insects causing death. So wouldn't the pool DE with more crystalline silica be more effective?" No, because the heat treatment makes it form larger clumps which makes it less able to get at the insects like the finer garden grade.

At some point a long time ago I investigated the diatomatious earth. If I remember right the diatoms are shaped like tiny starfish. When they die the tips of their exoskeletons break off and the arms become like tiny glass pipettes. These pierce the soft tissues on insects at their joints and such and wick out their juices which kills them. This is also how it acts as a filter it lets liquids pass but clogs up with solids and eventually needs back flushed or changed.

Actually, L_James, there are many different shapes. Some are kind of like starfish, and some are like barrels, and some are like teardrops with two pointed ends, and some are like Certs candy, etc. The killing action is often described as "slicing the outsides of the insects so they dessicate" because that's easier than the full explanation that's TMI for most people.

Here's how I understand it (I could be wrong on some details, but here's the gist of it): Insects with an exoskeleton don't have skin like we do to keep moisture inside their bodies ~ they have a waxy coating that serves that same purpose. The DE is incredibly absorbent due to the many nooks and crannies in between the sharp edges. As those edges scrape against the insects' bodies they scrape off that waxy coating and hang on to it (absorb it). Insects that don't have an exoskeleton and waxy coating, like aphids, live in a moist environment. DE works to kill them by drying up their environment. I wouldn't be surprised to learn that the DE does actually also cut aphids skin somewhat, but I really don't know for sure.

This is why DE isn't the most effective thing for slugs (too much moisture to soak all of it up unless you drowned them in it) or caterpillars (skin too thick for microscopic diatom shells to cut through).

how is it then, that the food grade DE is safe, and not a danger to lungs ?

Food grade DE has 1%-3% free silica as opposed to the 60% or more in pool grade DE. That's what constitutes the problem.

And food grade DE should NOT be handled without care, even with that very low percentage. But the hazard is obviously less.

It's the particles of DE that do the job on arthropods, not the amount of free crystalline silica. Pool grade DE has been heat and chemically treated. Those sharp surfaces no longer exist.

I bought and I'm using the garden grade of DE I also wear a mask and gloves when using it. kittlin's input is what I read about DE I believe to be true. I directly apply to the ears and stalks of my corn it appears to working really well. It's suppose to work on crawing critters.

I doubt if the white butterfly worm would be affected, unless DE could be kept on the plant for a period of time. They spend most of their time on the undersides of such veggies as cabbage and broccoli. Unless their is a way to make DE stick, it probably wouldn't be too effective.

BT is recommended for the cabbage worm usually. Hand picking if not too numerous. I did use a small amount of 7-Dust last year on one cabbage that I used as a trap crop. It seemed to work well for subsequent plantings, once the cabbage worm threat was over (usually cooler weather).

Bejay

"how is it then, that the food grade DE is safe, and not a danger to lungs ?"

Because garden grade DE is mostly just silica, not crystalline silica ~ pool grade DE is mostly crystalline silica, not plain silica. Just like I said above, just plain silica is usually harmless, but crystalline silica isn't. Crystalline silica can cause silicosis (scarring of the lungs) and cancer. The pool grade De being in crystalline form allows it to "hang on" inside your lungs and cause scarring instead of being flushed out like normal dust. Garden grade DE is easier for the cilia in your lungs (little hairs lining your lung passages that "flush" out particles) to push along with mucus and expel.

But, like Rhizo said, I still wouldn't say the garden grade is really "safe" to breathe in. If you have asthma, I can easily see doing so causing an asthma attack. And even if you don't have any lung problems, breathing in any kind of dust isn't exactly good for you. But the chance of it causing silicosis or cancer is significantly less, as in very-tiny-little-bitty chance.

the fact of the matter is, that anything other than air that is inhaled in lungs, is damaging.

That doesn't negate the fact that pool grade DE is different than garden grade, and can cause cancer. Give me a choice between inhaling just dust or crystalline silica and I'll pick just dust anytime.

well i see i am a jonny come lately to the DE talk. still i might have some input.

i live in Utah and we got in touch with a man that mines DE. he has a warehouse full of the stuff in north Salt Lake. we got a super deal to obtain DE from him.

well i am going to find his phone # adn ask him if there is a difference.

i have had great results with DE on cabbage. i do apply it several time during the season. when i harveat the heads the first 2-3 leaves have a clay like substance in them but not cabbage worms.

with corn i put it on the silk and i do not get corn worms.

also i had zero tomato worms.

i did not use any pesticides or herbicides.

i did not have sny sueash beetles until lat in the season

we had our first nip of frost two night ago and it hot my squash and cucumbers.

most of my tomatoes and my crenshaw are still ok.

i also mix two gallons of water with i cup of diah soap and three cups of DE and spray most of the garden.

Dean

"so then i guess that whenever you swim in a pool with a DE filter, your risking cancer, aren't you? for its a fact alot of the DE ends up in the pool via the ports."

Only if you are inhaling your pool water ;)

Dean, since your friend mines natural DE, might not even be aware of the factory process required to turn his product into pool filter DE. He might sell to those companies, however, who turn the mined stuff into the pool stuff.

Very interesting discussion about diatomaceous earth. Yes there is a huge difference between pool grade and food grade diatomaceous earth. All you have to do is ask for an analysis of the product and it will be plain to see. Anyone who is selling pool grade for food grade is being so selfish that they only care about getting your money, not taking care of you as a customer. Perma-Guard produces the cleanest food grade diatomaceous earth, only containing 05% Crystalline Silica.

Here is a link that might be useful: Perma-Guard Diatomaceous Earth