Esfenvalerate is losing its efficacy against oriental fruit moth in Michigan
Research conducted in 2017 provides new information on the use of esfenvalerate to manage oriental fruit moth.
Oriental fruit moth, Grapholita molesta, is a common insect pest in Michigan peach and apple orchards. In peach orchards, this moth causes damage to the shoots in the early season and fruits following shuck split. Oriental fruit moth has three generations per season, and peach growers must time effective insecticides to target the peak flights of the pest. Historically, the pyrethroid class of insecticides has been a popular choice in Michigan peach orchards because of their high efficacy, broad spectrum of activity and low cost.
However, following heavy damage to Michigan peach orchards during the 2016 growing season in spite of management with these products, many peach growers began to suspect resistance to the pyrethroid class of insecticides could be developing. In 2017, Michigan State University conducted insecticide bioassays on field-trapped adult oriental fruit moth collected from peach orchards in west central and southwest Michigan. Groups of oriental fruit moth were exposed to three concentrations of esfenvalerate. Esfenvalerate is the active ingredient in the widely used pyrethroid insecticide for oriental fruit moth, Asana, and its generic equivalents.
Unfortunately, 2017 results indicate this material is no longer a good choice for managing oriental fruit moth. Mortality in field-collected males to esfenvalerate was less than 50 percent in all test groups, and fell as low as 13 percent in some treatments. Avoid depending on products with esfenvalerate for managing oriental fruit moth if you are in regions where pyrethroid insecticides have been routinely used on apples and peaches. Data on other pyrethroid insecticides is not yet available.
Pyrethroid insecticides have value for managing other insects such as tarnished plant bug, and there is some evidence that resistance of oriental fruit moth to pyrethroids declines when other effective insecticides are included in rotation. MSU will continue studies on oriental fruit moth susceptibility to this product and other pyrethroid materials in 2018.
Summarized below are the non-pyrethroid insecticide options to pick from when considering future management plans for this insect pest.
Non-pyrethroid insecticides registered for managing oriental fruit moth.
|Compound trade name||Chemical class||Effectiveness||Residual activity|
|Voliam Flexi||Premix||Excellent||10-14 days|
Other insecticides with pyrethroid class active ingredients are also likely at risk at this time. While data on additional products will be coming in 2018, use caution with the products on the table below. Note that the rating label on all these products is “excellent,” but based on recent data there is some doubt on their accuracy.
Pyrethroid-based insecticides registered for managing oriental fruit moth.
|Compound trade name||Chemical class||Current labeled effectiveness rating||Residual activity|
|Voliam Xpress||Premix||Excellent||10-14 days|
MSU Extension suggests deploying mating disruption for oriental fruit moth in peach orchards to help combat the pest. Populations of oriental fruit moth in many areas of the state are very high at this time, and deploying this strategy will help curb population growth in orchards. Do not be discouraged if high populations of oriental fruit moth persist for a year or two after you begin using this practice; the oriental fruit moth populations likely took several years to get this high and may take time to go back down again.
Deploying effective insecticides timed with peak flights along mating disruption will help peach growers get back to a reasonable management scenario for this pest.