Blueberry Insect Scouting Report for April 8-16, 2012
Cherry fruitworm management season is here again for Michigan blueberry growers.
The MSU Blueberry Team is moving to a new format for information delivery in which timely articles and these scouting reports will be prepared for online delivery at www.blueberries.msu.edu and MSU Extension News. Due to personnel changes and moving to new formats for information delivery, there will be no more PDF format scouting reports each week. Instead, all the MSU Extension blueberry information will be posted at blueberries.msu.edu. If you want to get an email alert when new articles are posted, just go to the bottom of that webpage and sign up for the RSS feed. Or just check back regularly for new information, such as these scouting reports. Another option is to signup for the MSU Extension News digest to receive an email when new fruit production articles are posted at MSU Extension News. Please note that with this choice you will get all fruit-related articles from MSU. Be sure to select the fruit category from the list of choices. Please let us know what you think of this new format.
With support from a USDA grant, throughout the 2012 growing season we will be scouting six blueberry farms located in Van Buren and Ottawa counties, and reporting insect activity each week. The farms are located from Paw Paw to West Olive, and as this represents a large range of the blueberry growing region of Michigan, it should allow us to alert blueberry growers when pest insects are active. These reports are not a replacement for scouting on your own farm, but rather should be used as a reminder of when and how to scout and what symptoms to look for.
In Van Buren County, Jersey in Covert is at mid-late pink bud, and Bluecrop and Rubel in Grand Junction, Paw Paw and Gobles are at trace bloom. In Ottawa County, Jersey is at early pink bud and Bluecrop is at mid-late pink in West Olive.
Weekly insect pest report
With the early spring weather and advanced crop development, we have already hung cherry fruitworm (CFW) traps at all the farms we visit in Van Buren and Ottawa County. CFW moths have now been trapped in Paw Paw, Covert and Grand Junction over the past week, and we expect to see the flight of this pest increase over the next week. In West Olive we have not caught CFW moths as of Thursday April 12. We expect to see the beginning of flight (which occurs 200 to 250 growing degree days, or GDD, base 50oF after March 1st) in Ottawa County this week. At all locations we are catching a contaminant moth in CFW traps. This moth is larger than a cherry fruitworm moth and with mottled dark patterns on the wings, while CFW is dark with a series of thin shiny bands across the wings. See this previous article for pictures to help distinguish these two moths and for more information on fruitworms.
Growers and scouts should be checking CFW traps now to ensure detection of the start of the flight for this pest. Traps should be baiting the traps with a pheromone lure and hanging the trap in the top half of a bush on the perimeter of a field. Place traps in known "hot spots" where the pest has been seen in the past. These areas are generally adjacent to woodlots, so if you are not sure if you have CFW, these are the best areas to begin trapping. Put traps in the outer part of the canopy on a sturdy branch.
Traps should be checked twice weekly until moths are caught consistently. This will not only identify fields with pressure from cherry fruitworm, but will also enable the identification of the start (biofix) of CFW flight, when moths start to be consistently trapped. The first chance of egglaying by CFW is predicted to be 100 GDD after biofix, so this timing can be used to protect fields that have had significant infestation from this pest previously and where fruit set has started at 100 GDD after biofix. See this detailed article about fruitworm management for more information.
For cranberry fruitworm (CBFW), the main fruitworm pest of blueberries, current degree days and predictions suggest that its flight will begin after this week. Still, this would be a good time to hang CBFW traps for cranberry fruitworm to ensure a few weeks of zero catch for identifying the start of flight and the biofix.
Leafroller larvae are also active at this time, although no feeding damage was observed on the farms we scouted. To scout for leafrollers, examine 5 flower clusters and 5 leaf clusters on 10 bushes on the field border and 5 flower clusters and 5 leaf clusters on 10 bushes in the interior of the field. Look for leaf or flower clusters that have feeding holes or webbing in the cluster. These pests are generally not economically important in Michigan, and no treatment thresholds have been developed, but if 3 to 5% of buds have feeding damage, growers may want to consider a specific control targeting these insects. View more information and pictures of leafrollers from our scouting guide pages posted at blueberries.msu.edu.