Organic products are becoming more popular than ever, but their active ingredients may be different than the conventional products you are familiar with. Here is a list of insecticides and fungicides that may be listed on organic products you buy.
Bacillus Thuringiensis (Bt). Bt attacks leaf- and needle-eating caterpillars through ingesting the bacterium. Feeding stops within hours, although death may not occur for a few days. There is some controversy surrounding this ingredient, however, because Bt genes are being used in genetically modifying certain crops to make them more pest resistant.
Citrus Oils. Citric oil from citrus peels destroys the waxy coating in insects’ respiratory systems and is one of the more effective organic controls. It can harm aquatic invertebrates, however, so it should not be used near streams, ponds, etc.
Diatomaceous Earth (DE). DE, an abrasive powder, cuts the exoskeleton of crawling insects. Also, insects that ingest DE die within 48 hours. It may cause lung irritation in humans, so a mask is recommended for applicators.
Hot Pepper Wax. Hot pepper wax repels aphids, cabbage loopers, beet armyworms, spider mites, and white flies. It lasts up to 30 days and does not wash off easily. Avoid use on variegated African violets, sweet basil, parsley, Dicentra eximia, and fruit trees in bud.
Insecticidal Soaps. Insecticidal soaps are salts of fats and oils found in animals and plants. They work by dehydrating soft-bodied insects and require application every seven to ten days to infested areas.
Horticultural Oils and Sprays. Horticultural oils coat insects’ airways, as well as their eggs, and suffocate them. Be aware there are both organic and petroleum-based versions, so double check which is used before purchasing these products. These can damage plants in high temperature and low humidity conditions. Do not combine with sulfur. There are two primary types of horticultural oils: summer and dormant. Dormant oils are generally applied while plants are not actively growing, while summer oils are applied during the growing season.
Other Oils. Extracts from plant material, including garlic, clove, cedar, lavender, peppermint and citronella should not be confused with horticultural oils. They work by repelling and smothering insects.
Pyrethrins/Pyrethrum. Pyrethrins, made of the ground up flower head of chrysanthemum cinerariifolium, disrupt insects’ nervous systems. Most pyrethrins are toxic to cold-blooded animals. The similar sounding pyrethoids are synthetic compounds based on pyrethrins.
Spinosad. Spinosad is derived from a bacteria species discovered in 1982. It affects the nervous system and kills insects within a day or two of ingestion. It’s touted as a Bt replacement.
Bordeaux Mixes. Bordeaux mixes are a combo of copper sulfate and hydrated lime and should be applied in early spring. Leaf burn can occur when temperatures dip below 50 degrees Fahrenheit and in high humidity. Overuse can create copper build up in the soil.
Copper Sulfate. Apply copper, a preventative, when leaves can dry quickly. It’s toxic to aquatic creatures, so do not use near streams and ponds. It will build up in the soil.
Lime Sulfur. Lime sulfur controls foliar disease as well as mites, psyllas and some sap-eating insects. Do not overlap with horticultural oils.
Sulfur. Sulfur controls mites and prevents foliar disease. Do not apply to plants treated with horticultural oil within the past four weeks. Sulfur corrodes metal so a plastic applicator is best.