Pyrethrin's been seriously limited/removed from 'ok for organics' lists over here. It's a pretty nasty neurotoxin and it's not going anywhere near my garden!

I've always understood that pyrethrin is in the "big guns" of organic pesticides, and that it can be pretty darn toxic. What are you using it for? Have you tried less dangerous measures and have they failed?

Pyrethrin is one of the most toxic, broad spectrum poisons still organically acceptable, but it should be used only as a last resort method of insect pest control. Many years ago when I did use it I did not notice a "kerosene" like smell so that may be something added of late to let people know it has been sprayed or dusted around. Pyrethrins will kill many of the beneficial insects including the predators that could help control the pests as well as insect pests.

Wow! That's too bad. I've been using it on my spinach. It's my first time growing a garden and seems like I made a mistake in buying Pyrethrin. I have two types of spinach, one with triangular shaped leaves, which is doing OK, and a traditional one, which has a ton of holes in it. Are aphids the problem and what else can I use to control them?

Aphids don't make holes. It could be all sorts of things, but I'd be very wary about using unfamiliar toxins to combat something unidentified.
Anything that kills stuff is likely to have side-effects and don't imagine that organic=harmless.
First ID the critters. This forum's a good place to post photos...

Yep, I'd suggest not using the Pyrethrin for a while. You may not find what's killing your spinach, at least this year; the solution for now may be to grow something else. (Like maybe more of the other spinach?) Another year when you have more gardening experience, the cause of the problem might be more apparent.

I wouldn't necessarily say that you should _never_ use something as toxic as Pyrethrin, but I will say that I never have and likely never will. If my livelihood were dependent on saving a crop, or if I were, say, about to lose a unique plant that that could never be recovered from any source, something like that, I might. But for a regular, "I'd like to try growing my own !" crop, I'd just move on to something else.

feijoas said..."I'd be very wary about using unfamiliar toxins to combat something unidentified."

VERY well said!

Integrated Pest Management practices may help determine what, if anything, might need to be done. One thing to keep in mind is that possibly nothing needs to be done.
1. Is a problem that needs fixing?
Is the plants existance threatened. Can I live with the damage. Not every bite or blemish needs some kind of spray.
2. What is the true cause of the problem?
Is this from an insect pest or a plant disease?
3. What is the least toxic means of immediate control?
4. Apply that least toxic means of control.
5. Did that solve the problem? Do I need to do more? Return to step 1.