Pesticides Organic farming

a sign outside of organic apple orchard in pateros, washington reminding orchardists not spray pesticides on these trees

in organic farming synthetic pesticides prohibited. chemical said synthetic if not exist in natural world. organic label goes further , prohibit compounds exist in nature if produced chemical synthesis. prohibition method of production , not nature of compound.

a non-exhaustive list of organic approved pesticides median lethal doses:

copper(ii) sulfate used fungicide , used in conventional agriculture (ld50 300 mg/kg). conventional agriculture has option use less toxic mancozeb (ld50 4,500 11,200 mg/kg)
boric acid used stomach poison target insects (ld50: 2660 mg/kg).
pyrethrin comes chemicals extracted flowers of genus pyrethrum (ld50 of 370 mg/kg). potent toxicity used control insects.
lime sulphur (aka calcium polysulfide) , sulfur considered allowed, synthetic materials (ld50: 820 mg/kg)
rotenone powerful insecticide used control insects (ld50: 132 mg/kg). despite high toxicity of rotenone aquatic life , links parkinson disease compound still allowed in organic farming naturally occurring compound.
bromomethane gas still used in nurseries of strawberry organic farming
azadirachtin wide spectrum potent insecticide. non toxic mammals (ld50 in rats > 3,540 mg/kg) affects beneficial insects.




^ http://web.pppmb.cals.cornell.edu/resourceguide/pdf/resource-guide-for-organic-insect-and-disease-management.pdf
^ use , status of rotenone in organic growing - organic gardening . mother earth news. 
^ makes organically grown strawberry environmentally friendly? . tomorrow s table.