August 20, 2009 at 7:49 a.m.
Michelle Grabowski, U of M Extension Educator has been the instructor for a number of our Spring Series Classes, and Starr reminded me that Michelle has spoken of this new organic insecticide.
I contacted Sue Humble, the Chisago County Master Gardener Coordinator, and she researched information on Spinosad. Lynn Rawe, County Extension Agent-Horticulture, wrote an article for the San Antonio Express News entitled, Spinosad: An Insecticide to Make Organic Gardeners Smile. Rawe wrote that Spinosad was granted organic status by the USDA six years ago. However, few home gardeners are aware of its many uses. It's derived from the fermentation juices of a lowly soil bacterium called Saccharopolysporaspinosa. Spinosad is especially effective on caterpillars and thrips. The best thing about products containing spinosad is that it is safe around people, animals, and beneficial insects. It is even safe around adult butterflies and many insect predators and parasites.
"Bt" has been the standard organic weapon for the war against caterpillars. While Bt is good for one or two days, spinosad keeps killing for up to four weeks. In addition, spinosad kills thrips while Bt doesn't faze them.