Safe Organic Pest Control
Question: I have leaf miners ruining my lettuce and maggots ruining my radishes. Is there any control for these pests that does not leave dangerous chemical residues on my food?
Answer: Yes there are two wonderful organic pesticides which are completely safe to use on food crops and around children, pets and wildlife.
Spinosad is a compound derived from a bacterial species originally found on sugar cane. It is an organic pesticide with uses including cat fleas as well as for agricultural food crops.
It controls a wide range of insect pests including leaf miners, root maggots, borers, caterpillars, codling moth (apple worms), beetles, thrips and many more insects.
For leaf miners on lettuce and other leaf vegetables, spray the leaves at the first sign of damage. Repeat application at weekly intervals.
For root maggot control, spray the soil around plants of radish and other root crops as soon as seedlings emerge from the soil. It can also be sprayed over seeds before they are covered with soil.
To prevent wormy apples begin spraying fruit as soon as it reaches the size of the end of a finger and repeat at 2 week intervals.
Spinosad will also control insects on roses and other woody ornamentals including borers and caterpillars on trees.
The word “spinosad” may not be on the main label. You may have to check active ingredient labels to find it. It will most likely be available at full service nurseries and garden stores.
Neem oil is another organic pesticide derived from the neem tree. It is effective in controlling major insects as well as a number of leaf diseases. It is my favorite pesticide for roses since it controls both insects and diseases. Spray every 2 weeks on roses to prevent mildew and other leaf diseases.
Bacillus thuringensis (often referred to as B.T.) is a bacteria which causes disease in insects, especially caterpillars, within two days after they eat it. Recently formulations which are effective on beetles and grasshoppers have become available. B.T. is nontoxic to warm blooded animals. It is available in wettable powders and liquid concentrates under several brand names including Thuricide, Dipel, Biotrol and Attack.
Insecticidal Soap is produced from potassium salts of fatty acids and is effective in washing small insects and insect eggs off of plants. Most effective against aphids and mites.
Neem Oil is refined from the Neem tree and has proven effective for controlling a wide range of insect pests including mites. It also prevents spread of some plant diseases.
Paraffinic Oils are highly refined oils which can be used in warm weather and on green leaf tissue. Clove, thyme, and sesame seed oils are also sometimes used as insecticides.
Pyrethrum is a naturally occurring plant derivative contact insecticide with little residual action available in wettable powder and dust.
Rotenone is a natural plant derivative contact insecticide with little residual action available in dust form.
Other organic fungicides for plant disease control include sulfur, copper and horticultural oils.
Allen Wilson
Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.