Most insects are highly susceptible to pyrethrin at very low concentrations. The compound acts rapidly on insects, causing immediate knock down. Flying insects drop almost immediately after exposure. PBO, however, is not certified to be used on organic crops. Growers, who want to meet organic certification standards, should consult with the Colorado Department of Agriculture before using pyrethrin products.
Pyrethrum is non-toxic to most mammals, making it among the safest insecticides in use.
The Environmental Protection Agency has approved it for more uses than any other insecticide. Pyrethroids are synthetic materials designed to imitate natural pyrethrum. They can be used on houseplants, but because they are synthetic, they aren't registered to use on organic crops. Sulfur can be used as a dust, wettable powder, paste or liquid. Its primary use is to control powdery mildews, certain rusts, leaf blights and fruit rots.