Many organic pesticides come from plant sources, some of which produce pyrethrum, while others produce rotenone, ryania, or mineral-based pesticides. Mineral pesticides include cryolite, boric acid or diatomaceous earth—all of which are designed to kill plant-destructive insects in your garden.
Experts say that, while organic pesticides are distinctly safer than synthetic pesticides, users want to be careful when using them. Gardeners shouldn’t use them with bare hands and they should realize that some organic pesticides can be as toxic as their non-organic counterparts. Least toxic products will say “Caution” on the label, more toxic products will say “Warning” and the most toxic products will say “Danger”. These words, however, are not a signal of their potential for environmental harm.
Some organic pesticides are minimally toxic to humans but are very toxic to animals. Ryania, for example, is highly toxic to fish. Other organic pesticides kill even the most beneficial insects, such as the combination of pyrethrins and rotenone. By law, all pesticides, including organic pesticides, must be used precisely according to the instructions on the label.
Read the label before using any organic pesticide. An important group of “organic” pesticides is the biopesticide group. This unique class of pesticides involves using biological organisms to control pests. In general this type of organic pesticide acts slower than other organic pesticides and involves critical application times. Biopesticides reduce, rather than destroy, pest populations and they have a narrow target range with a specific mode of action.
Biopesticides have a limited shelf life as they are live organisms. There are two general types of organic biopesticides. They include biochemical and microbial-based organic iopesticides.
Biochemical pesticides include insect pheromones, odor-based chemicals that disrupt the insect mating cycle by interfering with the ability to find a mate. Pheromone-based traps can also be used to trap male insects, disrupting the mating cycle.Organic microbial biopesticides include those that come from genetically-changed fungi, viruses, protozoans or bacteria.
This type of organic pesticide suppresses the pest population by secreting toxins specific to the insects, causing disease in the pest population, interfering with the establishment of pests through competition and other modes of action. One type of organic biopesticide is the bacterium known as Bacillus thuringiensis, a soil-based bacterium that is toxic to several types of insect larvae but not to other things. This bacterium can be applied to plant foliage or incorporated into the genetic material of larger crops. It is toxic to the larvae of moths and butterflies. Other varieties are toxic to mosquitoes and black flies.
Gardening with organic pesticides is generally effective and healthier to the environment and the plants than synthetic pesticides and make a good alternative to using harmful chemicals on your garden.