Harvest-time insect warning for blueberry growers in Michigan

Michigan has had a mild winter and is experiencing a warm summer, leading to early activity of some insect pests as the peak of the blueberry harvest approaches. Michigan State University has seen an increase in catches of blueberry maggots and spotted wing drosophila at various monitoring sites in southwest Michigan over the past week. Growers with ripe blueberries should protect their fields with effective insecticides.

Figure 1. This image shows spotted wing drosophila (SWD) surveillance traps using yeast and commercial bait. It also shows the sampling method used to detect spotted wing drosophila larvae, which involves submerging fruit in salt water for 15 minutes. Photo by Carlos García-Salazar, MSU Extension.

For these pests, there are several options with high efficacy and short preharvest intervals that can be used during the harvest season. Recommendations can be found in Michigan State University Extension Bulletin E154, “Michigan Fruit Management Guide.” This publication is available in Hard copy and as downloadable PDF.

To determine the correct time to apply insecticide against spotted wing drosophila, place surveillance traps baited with brewer’s yeast or a commercially available attractant in the fields as shown in Figure 1.

The blueberry fly can be controlled by an application every 10 to 14 days, but shorter spray intervals are needed to protect against the spotted wing drosophila. You can also monitor berry infestation by taking weekly fruit samples from fields nearing harvest to ensure they are free of insects. Michigan State University has a short, 8-minute video Explain this method and give information about the simple equipment needed.

Source: canr.msu.edu