West central Michigan small fruit update – June 20, 2017

Strawberry harvest is still underway with excellent fruit quality, but it is coming to an end due to weather-related issues that shortened the harvest period.

After days of no rain and temperatures in the low 90s, west central Michigan received some much needed precipitation. For the past seven days, the region received between 1 and 1.25 inches of rain, and temperatures dropped back to much more comfortable conditions. Average daily minimum temperatures remained around 64 degrees Fahrenheit and the daily maximum around 78 F.

Although current weather conditions are improving, small fruit crops like blueberries, strawberries and raspberries still require supplemental irrigation to make up for the water deficit from the previous weeks. After the rains from the past week, the amount of precipitation accumulated in west central Michigan since Jan. 1 varies from 15.5 to 17.6 inches, depending on the location.

Strawberry harvest continues with fruit of good flavor and quality thanks to dry weather conditions that limited the presence of fruit rots at harvest time. However, fields that were affected by black root rot and other root diseases had to cut harvest short because plants started dying due to the plant’s increased water demand and the impossibility of the root system to keep up with plant’s needs.

Another problem that affected strawberry fields was the presence of bronzing caused by weather conditions and, in some cases, by an outbreak of thrips. This assumption seems to be correct since integrated pest management (IPM) scouts in the area reported heavy infestations of thrips in strawberry fields where bronzing was observed.

According to Michigan State University Extension entomologist Rufus Isaacs, “Thrips do like hot weather, and we have certainly had plenty of that during the past weeks”.

Thrips are not a frequent problem in strawberries in west central Michigan, but inspecting fields in search of thrips as part of our current IPM scouting is highly recommended. Also, a new insecticide, Radiant SC from Dow AgroSciences, is already in the market to control thrips problems. This is a version of the insecticide Delegate with current label for use in blueberries against spotted wing Drosophila.

Most blueberries varieties are still in the green fruit stage, but they continue sizing and the first blueberry harvest could start next week in early varieties in southwest Michigan.

Problems reported in blueberries are related to a heavy June drop in the varieties Jersey and Elliott due to a combination of drought and bad pollination. After the rains from the past few days, we are expecting conditions will improve in most fields. Supplemental irrigation is needed to compensate for the past weeks lack of precipitation.

Insect pest problems, on the other hand, are related to large numbers of cranberry fruitworm adults still trapped in blueberry fields. During the last week, cranberry fruitworm adults continued flying with large numbers still being caught in the area. Inspect your fields for signs of fruit damage and apply the recommended insecticides to prevent fruit damage.

For products and doses for controlling fruit worms, check the MSU Extension bulletin E0154, “2017 Michigan Fruit Management Guide.” If you need assistance with your spray program, call your local MSU Extension office.

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