West central Michigan small fruit regional report – August 16, 2016

Blueberry harvest continues with excellent fruit flavor and quality, favored by warm weather and rains that provided relief from the summer drought.

Weather conditions in west central Michigan have improved substantially from those observed during previous weeks. Daily maximum temperatures dropped from the upper 90s to the normal temperate conditions typical of Michigan’s summers. For the past seven days, the average maximum daily temperature was 83 degrees Fahrenheit and the daily minimum was 64 F. There were thunderstorms and rain showers on three consecutive days that left 2.15 inches of rain in the area, but some places got more than 2.5 inches during the same period.

Late-season raspberries started ripening, and during the past week some U-pick operations started harvesting. No major problems have been reported. Due to warm weather conditions and high relative humidity, growers should take care of fruit rots. Leaf rust and Botrytis gray mold should be controlled in susceptible varieties. Check the Michigan State University Extension2016 Fruit Management Guide” (E0154) for products and doses. Growers are managing spotted wing Drosophila (SWD) with clean harvesting and minimal use of insecticides.

Most blueberry growers are finishing Bluecrop for fresh packing and are concentrating their efforts on harvesting Elliott and Aurora fields. Fruit harvested for fresh pack has excellent flavor and quality, favored by warm weather and rains that provided relief from the summer drought. For processing, the harvest of Jersey fields and leftovers from Bluecrop continue in the central region.

Growers have been able to maintain excellent fruit quality despite the summer drought and problems associated with the presence of SWD in their fields. Improving weather conditions helped maintain an effective control of SWD at harvest time. Some additional recommendations for SWD control are:

  • Do not rely on the seven-day protection that some insecticides provide under spring temperatures. Short spray intervals are required under current summer temperatures.
  • Adjust the spray volume to compensate for evaporation and loss of spray volume due to high temperatures. Use more than 25 gallons of water to increase the penetration of the insecticide into the bush.
  • Try spraying at hours when the temperature is below 75 F, like during the evening when temperatures are lower and the relative humidity is higher than during the day.

For a complete list of recommended insecticides and doses for SWD control, check the “2016 Fruit Management Guide,” or contact your local MSU Extension office for assistance. You may also contact me at 616-260-0671 or garcias4@msu.edu.

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