There are approximately 20,000 acres of onions grown in the Treasure Valley production area of Eastern Oregon and Western Idaho.
Growers apply two to four insecticide applications to control onion thrips.
Previous tests have shown that most of the registered insecticides were ineffective and gave poor to moderate control of thrips. Therefore, the purposes of this research were to determine if 15 insecticide treatments are effective in controlling thrips, and to collect data for possible registration of the insecticides. The trial was established on the edge of a commercial onion field near Ontario. The trial area was in an irregular part of the field that could be isolated from regular insecticide applications. Pretreatment thrips counts were made on June 22 by counting the total number of thrips on five plants in each plot.