Growers have become aware of the results of this project through the numerous presentations and publications, making the WSU Extension Commercial Vegetable program in the Columbia Basin the main source they use for information on insect management in onions. Prior to the initiation of this research project, growers commonly used pyrethroid insecticides to target control of onion thrips. This project has shown that pyrethroid insecticides are ineffective and, in fact, thrips are resistant to this commonly used class of insecticides. As a result, producers have ceased use of this insecticide and have shifted to using more effective insecticides that have been identified by the research conducted on this pest by WSU Extension.
The newer insecticides often are slower acting and narrower in spectrum of control than previously used insecticides; therefore, applying them with the same timing and application methods would not be effective. The WSU Extension Commercial Vegetable program has determined the best timing and application methods for new insecticides. This helps growers know when and how to use these insecticides for optimum results. The new insecticides are applied at lower rates and are safer for the environment and non-target organisms than the older insecticides. Additionally, the improved application methods (applying via drip or center pivot irrigation) are less expensive and more effective than foliar applications.
Narrower spectrum insecticides have been widely adopted by onion producers in Washington. In fact, greater than 60% of the insecticide applications in onion fields are with narrow spectrum insecticides. Furthermore, producers have shifted from using broad spectrum insecticides early in the season to using the broad spectrum compounds late in the season, or not at all in order to preserve beneficial insects in onion fields.
Studies conducted in 2010 showed that when the most effective insecticides were utilized in thrips management programs in onions, yields increased by 25%. A 25% increase in onion yield translates to at least $2,400 more in net profit per acre for growers who use these treatments, using the 2015 onion market value. With 24,000 acres of onions in WA, if 20% of users implement these changes, the WA onion crop value would increase by $11.5 million annually.
"The Sunheaven Farms growers put a high value on the thrips research and advice that Tim Waters of WSU Extension provides. Thrips are a major pest on our farms, and controlling them has become a challenge. Without successful thrips control the value of our produce would drop drastically. ... Tim's research and screening of new pesticides and application techniques has been a lifesaver for us. Before Tim was here, we depended on research from other areas, which sometimes was not pertinent to the Columbia Basin. Tim's work is done with local cultural practices in mind and his program is integral to the success of controlling insect pests on our farm and many others in the Columbia Basin." - Wes Locke, Agronomist, Sunheaven Farms
"Much of the research WSU’s team and the local people, Tim Waters and Carrie Wohleb, have conducted helped us to improve the quality of our crop. The ongoing work on thrips control and timing of these newer pesticides are very important. Tim and Carrie have developed respect with the independent-minded onions growers and I know they will continue to be helpful in the future." - Larry Bauman, L and L Ag Production
For more information, please contact Tim Waters, Franklin County Extension Director
404 W. Clark, Pasco, WA 99301, call: 509-545-3511, Ext. 6001, or email: firstname.lastname@example.org.