West central Michigan small fruit regional report – June 7, 2016
A large cranberry fruitworm emergence occurred last week, and although no fruitworm damage has been reported in blueberries, eggs are being found in fields.
Cool and dry weather conditions have prevailed for the most part during the past seven days in west central Michigan. Minimum daily temperatures were on average 55 degrees Fahrenheit, and the maximum averaged 77 F. There were a few scattered showers that left a precipitation accumulation of 0.33 inch, which was not enough to supply the water requirements of our major small fruit crop, blueberries.
Currently, the blueberry crop has proceeded without major problems. Starting from Allegan County and heading north, blueberries are in green fruit stage with a very large fruit set in all varieties. Since not enough precipitation has been recorded in the area, there has been a need for supplemental irrigation. So far we are not seeing the “June drop.” However, if not enough rain occurs in the next seven days, we will start seeing some fruit drop due to water stress, especially in fields without irrigation. Therefore, growers should provide supplemental irrigation to maintain a healthy crop.
Problems in blueberries are associated to the presence of insect pests. During the past seven days, there was a large peak of cranberry fruitworm adults trapped in the area, much larger than the cherry fruitworm population that has remained at a low population density. However, we have seen cherry fruitworm eggs in Ottawa County, but no cranberry fruitworms despite the large emergence of adults during the past week.
Based on our current observation of the behavior of both species, it is expected that cranberry fruitworms represent the main concern for pest control this year. The fact that cranberry fruitworm population peak occurred at the end of the bloom period facilitates its control because at this time, most of the bees have already been removed from the fields. This allows better fruitworm management and allows growers to control secondary pet problems like blueberry stem gall wasp with broad spectrum insecticides. Recommended insecticides for fruitworm control with activity against secondary pest such as blueberry stem gall wasps are Lannate, Mustang Max, Assana XL and others with similar activity. For a complete list of products and doses, please consult the “2016 Michigan Fruit Management Guide,” Michigan State University Extension bulletin E0154.
In addition to secondary insect pests occurring during the blueberry bloom period, such as blueberry stem gall wasps, we are also finding blueberry gall midge, Dasineura oxycoccana (Johnson), in blueberry fields in Ottawa County. We are observing blueberry gall midge attacking the blueberry terminal growth in fields planted with varieties such as Bluecrop and Draper. Although the damage is not significant, it is good to keep observing the progress of this pest in the area. So far, no chemical control is required against blueberry gall midge since applications of insecticides against fruitworms are taking care of blueberry gall midge larvae.
Traps for spotted wing Drosophila are already deployed in Allegan and Ottawa counties. No spotted wing Drosophila have been caught.
Good Agricultural Practices (GAP) training for Hispanics
On June 3-4, 2016, we conducted the first GAP workshop for Hispanics. The event was attended by 20 growers. On the first day we reviewed the GAP main topics related to blueberry production. On the second day we reviewed and practiced the risk assessment procedures and visited several farms. Participants also received a format to start developing their GAP manual.
We will conduct another GAP training (Bilingual) June 17-18, 2016. For those that attended the June 3-4 training, there will be a follow-up on June 17. A complete description of the program and the agenda will be published on MSU Extension Fruit News soon.
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