Grand Rapids, Mich., small fruit regional report – September 26, 2012

Small fruit production end of season housekeeping – late season crop management issues.

We are at the end of the 2012 harvest season, but there are still some issues related to pest management that we need to take care of. First of all, fall raspberries and some day-natural strawberries continue with harvest and there‘s still a need for monitoring and controlling the presence of spotted wing Drosophila (SWD). During the past two weeks, we have seen a large number of farms experiencing SWD infestations. The damage caused by this pest is reaching up to 10 percent in some day-neutral strawberry fields, but in raspberries the observed damage reaches up to 50 percent, and in some cases, 100 percent in organic-grown berries. SWD infestations in summer strawberries were uncommon, but since the middle of August the reports of fruit infested with SWD larvae increased.

During the past two weeks, we had good results in controlling 99 percent of SWD larval infestations in four raspberry fields located in Hudsonville, Casnovia and Rockford, Mich. After suffering high crop losses and with SWD adult populations of more than 50 flies per trap, growers implemented a control program that included adult monitoring twice a week and fruit inspection for SWD larvae, insecticide applications at first detection of flies or infested fruit, and subsequent monitoring of adults and fruit infestations to verify the effectiveness of the pest control measures. If larvae were found after the insecticide application, the treatment was repeated. The insecticide that provided the best protection against larval infestation was Malathion Aqua using the label maximum recommended rate.

For blueberries, there are issues other than SWD that need grower’s attention. At this time of the year, it is important for growers that used pyrethroids for the control of SWD during the season to inspect their fields for bud mites. Multiple applications of pyrethroids may flair up mite populations. Since 1988, Penman and Chapman documented the effect of multiple applications of pyrethroids on mite outbreaks in Pesticide-Induced Mite Outbreaks: Pyrethroids and Spider Mites. Also, in 2001 Bowie reported in Sublethal effects of esfenvalerate residues on pyrethroid resistant Typhlodromus pryi (Acari: Phytoseiidae) and its prey Panonychus ulmi and Tetranychus urticae (Acari: Tetranychidae) that some pyrethroids reduce the reproduction of predatory mites. Thus, it is important to maintain a continuous surveillance on that status of the mite populations, especially in those fields with history of bud mite problems.

Every year, we invite growers that need support with bud mite identification and control to bring in fresh blueberry shoot samples to the Trevor Nichols Research Center (TNRC) in Fennville, Mich., or at the Ottawa County MSU Extension office in West Olive, Mich. We are providing mite identification free of charge to any growers that require assistance with this problem. In order to provide this service, we need growers to follow these recommendations:

  • Bring freshly cut shoot samples in a zip-lock plastic bag with a moist paper towel inside to maintain plant tissue freshness. Do not bring or send in wilted or dried-out samples.
  • Bring at least 10 shoot samples per field or variety.
  • Write you complete information on the plastic bag.
  • Place the plastic bag with the sample in the TNRC kitchen refrigerator with a note indicating that the sample is for Carlos Garcia. If you bring multiple samples, put them all together in a large, plastic bag. If you bring the sample(s) to the Ottawa County MSU Extension office, drop them off at the front desk with any of the secretarial staff. We are open from 8 a.m. to 5 .p.m., closed for the lunch hour from 12 to 1 p.m.
  • Contact Judy Hanson at the Ottawa County MSU Extension office at 616-994-4548 to let her know that you dropped a plant sample at the TNRC for bud mite identification.

If you cannot bring the sample to those places, you may send them overnight to:

Carlos Garcia/Judy Hanson
MSU Extension
12220 Fillmore Street, Suite 122
West Olive, MI 49460

Do not mail samples to the TNRC in Fennville, Mich., because nobody will be available to receive it. Also, do not send overnight samples on Fridays to the Ottawa County MSU Extension office.

Finally, we are inviting all Michigan berry growers that experienced problems with SWD in their crops to attend the growers meeting on Wednesday, September 26, from 6 to 8 p.m. at the Trevor Nichols Research Center, 6237 124th Avenue, Fennville, Mich. (view map). This will be an informal discussion with growers, processors and MSU Extension staff Rufus Isaacs, Carlos Garcia and Mark Longstroth about the pest management challenges of 2012. This meeting will include a discussion of the tactics that were tried, the approaches that were effective and how to prepare for 2013. We will also generate a grower-developed priority list to help guide the pest management regulatory issues related to spotted wing Drosophila management, extension programs and short- and long-term research.

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