Remember, just because a pesticide is organic doesn’t mean it does no harm. Always follow the label directions and keep in mind that more is not better, even with organic products. Keep a close eye on your garden and try to catch problems early. If you practice good integrated pest management, with a wide range of plants, good growing conditions, natural predators, like birds and beneficial insects and healthy soil, you should not need to reach for a spray very often.
Insecticidal Soap
Ingredients: Insecticidal soap is sodium or potassium salts combined with fatty acids Application: Insecticidal soap must come in direct contact with the insect. It is no longer effective once it has dried How It Works: The fatty acids in the soap penetrate the insect’s outer covering and cause the cells to collapse Pros:
One of the safest pesticidesNon-toxic to animalsNo residueYou can use on vegetables up to harvest
Cons:
Can burn or stress plants. Don’t use in full sun or high temperatures. Does not work well for adult beetle pests which have developed a hard shell.
Precautions: Check label for specific plants that may be sensitive to insecticidal soap
Diatomaceous Earth
Ingredients: Silica from the skeletons of tiny aquatic animals. Application: Powder that is dusted on plants. May also be available in wettable powder or spray form. How It Works: Absorbs fats and oils from the insect’s exoskeleton causing it to dry up and die. Sharp edges help to pierce the insect allowing the powder to work quickly. Pros: Remains active for a long period as long as it is kept dry.
Bacillus Thuringiensis
Bt (Bacillus thuringiensis) Ingredients: bacteria. There are more than 80 types of Bt used as pesticides Application: Generally available in powdered form that is sprinkled or dusted on a plant. It must be eaten by the targeted insect How It Works: Bt is a stomach poison. It releases toxins in the stomachs of susceptible insects which cause them to stop eating and starve Pros: Bt strains are very host-specific (hornworms, corn earworms, cabbage loopers and other caterpillar pests) and will not harm people, pets, birds or bees Cons: Slow acting. It may take days for the insect to completely stop eating and die. Breaks down quickly, especially sunlight. Can kill ‘good insects’ like butterfly larva. Precautions: Follow the label directions and don’t overuse it
Neem
Ingredients: Contains 2 ingredients, azadirachtin and salannin, both from the seed kernels of the neem tree fruit Application: Sprayed onto plant leaves How It Works: Upsets the insects’ hormonal system and prevents it from developing to its mature stage. Most effective on immature insects Pros: Non-toxic to humans Cons: Washes away in rain. Slow acting. Breaks down in sunlight. Indiscriminate pesticide Precautions: Keep pets from treated leaves until they dry
Horticultural Oil
Ingredients: Highly refined petroleum oil Application: Mixed with water and sprayed onto foliage How It Works: Coats and suffocates insects or disrupts their feeding Pros: Low toxicity to humans, pets or birds. No toxic residue Cons: Most effective against soft-bodied insects. Can cause bluish evergreens to temporarily lose their blue tint. Can burn leaves Precautions: There are several grades. Be sure to use the one that is right for the season in which you are spraying
Pyrethrins
Ingredients: Derived from Chrysanthemum cinerariifolium Application: Generally found in powder form and dusted on leaves. How It Works: Poisons the insect, causing a quick death
Pros: Quick acting. Low toxicity to animals. Degrades within a day.Cons: Broad spectrum insecticide. Kills any insect. Very toxic to honeybees
Precautions: Use cautiously, only when you have a major problem with hard-to-kill insects
Sabadilla
Ingredients: Ground seeds of the sabadilla lily Application: Comes as a fine powder and used as a spray How It Works: Acts as a stomach poison Pros: Very effective against the true bugs (members of the Hemiptera order) Cons: Highly toxic to bees. Very irritating to the mucous membranes of mammals Precautions: Use as a last resort
Rotenone
Ingredients: Derived from the roots of tropical legumes Application: Dust onto plant How It Works: Inhibits a cellular process, depriving insects of oxygen in their tissue cells Pros: Low residual effect. Breaks down quickly in sunlight Cons: Broad spectrum pesticide. Mildly toxic to humans when ingested. Precautions: Apply in the evening, when bees are less active. May specify a “wait” interval before harvesting.
Potassium Bicarbonate
Ingredients: Potassium bicarbonate usually combined with horticultural oil and/or a substance to improve spreading and coverage of the leaves. There are commercially available products such as GreenCure® and Kaligreen, or you can prepare your own. Application: Spray at the first sign of disease or use as a preventative before infection How It Works: It’s still unclear, but it appears that bicarbonates can damage the cell wall and possibly create a pH that is not conducive to further fungal growth. The effect is immediate Pros:
Lasts 2 - 3 weeks as a preventativeYou can use on vegetables up to harvest
Cons: Can burn plants, especially if used in full sun Precautions: Check label and test on a small area before spraying the entire plant
