In WA some apple orchards are sprayed with kaolin (a fine white clay). http://en.wikipedia.org/wiki/Kaolin_spray. Diatomaceous earth is also used on some crops. Both of these are like... mechanical insecticides.

This page lists many "less toxic" insecticides - http://www.clemson.edu/extension/hgic/pests/pesticide/hgic27....

The replies in this thread from people claiming to be farmers are odd -- what crop? It seems pretty important. It sounds like it's hard to grow certain wine grapes some places, ok, but why do we have lists of the 'best' and 'worst' fruits/veggies to buy organic? They have less pest problems to begin with is my assumption, but I'm not really a farmer [beyond 10'x10' of herbs and veggies in the backyard].

herbicides: pelargonic acid (Scythe) and acetic acid are famous examples, but glyphosate (Roundup) and imazaquin (Image) have higher LD50s than table salt.

insecticides: Bacillus thuringiensis Cry proteins (used both in organic agriculture and in Monsanto's Bt lines), RNAi

Having a higher LD50 than table salt does not establish that a substance does not have serious long-term effects even at low doses.

no, I didn't say it did. But there's also no convincing evidence that either of the synthetics I mentioned does cause negative long-term effects (let alone serious ones).

Vinegar is a herbicide.

Concentrated urine as well.

Thanks. That's an interesting response.

However, the statement in question was explicitly regarding pesticides, not herbicides. And, implicitly, the context is those pesticides which are in use at scale on non-organic crops.

Nicotine would classify as insecticide that, while perhaps not completely benign, is considered to have minimal impact on human health (smoking it notwithstanding). A synthetically derived form of nicotine is the primary insecticide in use these days, although it's incredible success with the insect population is starting to give us second thoughts about using it.

IIRC, nicotine is a seriously powerful poison that can be absorbed through your skin, and mLs are all that's needed to kill a person?

Keep in mind that even if a compound is suitable for use at scale it might cost slightly more than current methods and therefore see almost no use.

Yes. But going back to my original question, it was in response to the statement that there are "almost unbelievably benign" pesticides with regard to human and environmental impact.

So, while there was also an implication that we're talking about pesticides that might see practical use, I'm really not even holding out that requirement. I'm just inquiring into the names of those pesticides that are benign to both humans and the environment.

I replied a few levels up mentioning kaolin spray (http://en.wikipedia.org/wiki/Kaolin_spray).

For more information about 'particle films' (like kaolin spray) see this document. There are numerous compounds mentioned and very interesting references too. These techniques also can be mixed with conventional pesticides and achieve the same efficacy as pure pesticide.

Particle Films: A New Technology for Agriculture - http://blog.meyvelitepe.org/images/Book_Chapter_Particle_Fil...

"At the present time, a commercial particle film material, Surround crop protectant, is being used in about 90% of the Pacific Northwest pear market for the early season control of pear psylla and approximately 20% of the Washington State apple market to reduce sunburn damage."

Herbicides are a sub-class of pesticides, so benign herbicides definitely count.

used coffee grinds, for one, make excellent pesticides for certain pests and are completely harmless for humans to handle.