Natural Controls for Summer Plant Insects and Diseases

Some insects and diseases are worse during hot weather. Insects multiply faster and some diseases grow faster during hot weather. Check your plants more frequently for holes and discolored leaves. Because most pesticides do not kill insect eggs, a followup application should be made about 2 weeks following the first application. By then most eggs have hatched but are not mature enough to produce more eggs.

Two of the best natural pesticides are Neem Oil and Spinosad. Neem Oil is extracted from the Neem tree. It is effective against both insects and diseases. Neem is not very long lasting so application at one to two week intervals may be needed if you have a continuing problem like black spot on roses.

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. Spinosad controls a wide range of insect pests including leaf miners, root maggots, borers, caterpillars, codling moth (apple worms), beetles, thrips and many more insects. The word “spinosad” may not be on the main label. You may have to check active ingredient labels to find it. Neem oil and Spinosad are usually available at full service nurseries and garden stores. If you notice a plant problem, feel free to call or email me for advice.  360-606-5437,


Allen Wilson

Allen has been writing about gardening for over 30 years. He is a retired professor of Horticulture.

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