Blueberry Insect Scouting Report for June 25-July 1, 2012

Monitor and protect fruit from harvest-time pests.

Crop stages

The first harvest of Bluecrop is underway in Van Buren County and early varieties have been picked multiple times. Bluecrop harvest should begin this week in Ottawa County.

Weekly insect pest report

The most important pest news is the steady increase in the number of spotted wing Drosophila (SWD) caught in traps as well as the increasing number of traps and sites that have captured SWD increased over the last week. This increase has been most evident at the farms we visit in Ottawa County, but the number of flies caught and the number of sites where flies were caught is also rising at the Van Buren County farms where we scout.

We are still catching mostly female SWD in yeast-baited traps and most have been caught in crop fields. Growers should be aware that if this pest has been caught on your farms you should protect the fruit as it becomes ripe because this is the period of highest 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.

Blueberry maggots are still emerging at some sites, but numbers have been very low at the farms we visit. Growers and scouts should be checking monitoring traps, especially in areas where blueberry maggot has been an issue previously. 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 beetle numbers are still low, but beetles have increased at all the farms we visited last week. Very little feeding damage was observed on leaves or fruit at the sites we visited. 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. 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 picking. Read more about Japanese beetle at blueberries.msu.edu.

Blueberry aphid colonies are still present in some fields, but they are becoming harder to find as the season progresses. This decrease is most likely due to insecticide applications. Parasitized aphids are increasing slightly, but numbers are still low. Growers and scouts should continue to monitor aphids in order to assess the amount of control achieved by recent insecticide applications and to help decide if reapplication is necessary. To scout for aphids, examine two young shoots near the crown on each of 10 bushes and record the number of shoots where aphids are found. Also, record the number of shoots with parasitized aphids. Be sure to sample weekly from as wide an area in the field as possible to have a better chance of detecting whether aphids are present.

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

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