Question: This picture shows my chewed Genovese basil. If you enlarge it, you will see small insects resembling those who ate the leaves of the plant. What can I do without poisoning my basil? (Editor’s note: Visit Bob Morris’ blog at xtreme horticulture.blogspot.com for a picture.)
The feeding looks more like a larger pest such as root weevils or caterpillar to me. Smaller insects would be more likely holes throughout the leaf rather than on the edges of the leaves. Soap and water sprays have to come in contact with the insect.
Organic types such as Bt (Dipel or Thuricide) or Spinosad will focus a lot on the caterpillar types and give you some overnight protection if done at dusk and would be a good first effort. Follow label directions. If this does not work, then I would move toward one of the pyrethrin or pyrethroid products with vegetables or herbs on the label. Check the ingredients for these products.
Bob Morris is a professor emeritus in horticulture with the University of Nevada and can be reached at firstname.lastname@example.org. Visit his blog at xtremehorticulture.blogspot.com. For more, see Thursday’s Las Vegas Review-Journal.