Blueberry Insect Scouting Report for July 8-14, 2012

Growers are keeping ahead of spotted wing Drosophila, but it is not over yet.

Crop stages

Harvest is in full swing at the sites we visit in Van Buren and Ottawa counties. In both areas, Bluecrop harvest is nearing completion and first harvest in Jersey is also almost done. Elliot harvest is, at most, only one to two weeks away at the sites we scout.

Weekly insect pest report

The number of spotted wing Drosophila (SWD) caught in yeast-baited traps decreased over the last week as fields with ripe fruit are getting treated to prevent SWD infestation. We are still seeing higher numbers of flies captured in Ottawa and Allegan counties compared to Van Buren County. We have continued to sample fruit with the salt bag test method and no larvae have been detected at the farms we visit.

We are still catching mostly female SWD in yeast-baited traps and most have been caught in crop fields, but the number of male flies trapped has increased greatly over the past week. Growers should be aware that if this pest has been caught on your farm you should protect the ripening and ripe berries because this is the period of risk from infestation by SWD. Through the ripening period and harvest, traps should be checked at least once per week. Be sure to replace the bait in the trap each week for maximum efficacy. For more information on managing spotted wing Drosophila, see the recent MSU Extension News article Managing spotted wing Drosophila update.

We did catch blueberry maggot flies at the farms we visited in Van Buren County this week, and catches of this pest are still occurring at several sites across areas of blueberry production in Michigan. We expect to see fly emergence increase, particularly if the rain that is forecast reaches the ground. Although sprays for SWD are likely to control blueberry maggots, growers and scouts should still be checking traps, especially in areas where blueberry maggots have been an issue previously. Be sure to replace ammonium acetate bait containers to keep the traps attractive to the flies. For more information on monitoring and controlling blueberry maggots, including pictures of traps and pictures of the pest, see the MSU Blueberry Facts website or a previous article in the June 21, 2011, Blueberry IPM Newsletter.

Japanese beetles increased in several fields at the farms we visited last week. The increase was seen in areas that had recently been picked and irrigated and were awaiting an insecticide application for SWD. Feeding damage on leaves or fruit is still very low at our scouting sites, and this is probably due to insecticide applications.

Even with all the SWD management activity, there are still reports of Japanese beetles being present at harvest time. Regular monitoring will aid growers and scouts in timing control measures to keep fields clean of Japanese beetles before harvest and reduce the possibility of contamination during machine harvest. To monitor for Japanese beetles, examine 10 bushes on the field border and 10 bushes in the field interior and record the number of beetles on each bush. Keep in mind Japanese beetles are normally more common adjacent to grassy areas on sandy soils, and they prefer to be in sunny areas. Read more about Japanese beetles at

Dr. Isaacs’ work is funded in part by MSU‘s AgBioResearch.

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