West central Michigan small fruit update – June 2, 2020

Blueberries are in full bloom and early varieties are at petal fall. Bees are very active in all small fruit crops and pesticide applications need to be made to avoid exposing pollinators to harmful pesticide products.

Strawberry damage by flower trips
Strawberry flower and fruit damage by early outbreak of flower trips. Photo by Carlos Garcia MSU Extension.

Small fruit crops are moving along very fast because of warm temperatures from the past two weeks. Daily minimum and maximum temperatures during the past seven days averaged 55 and 75 degrees Fahrenheit, respectively. Maximum daily temperatures in west central Michigan reached up to 90 F, allowing an accumulation of 340 growing degree days (GDD) base 50 F since March 1. During the past seven days, daily GDD accumulation was between 20 and 25 GDD per day. This was quite different from past weeks when daily accumulation remained below 10 GDD per day. Regarding precipitation, there were scattered rain showers that left less than 1 inch of precipitation in the area.

Small fruit crops are progressing very fast, favored for prevailing good weather conditions.

Strawberries are in full bloom and early varieties already have thimble-size berries. Despite low temperatures that occurred during mid-May, no spring frost injuries were reported by growers. However, there are some problems associated with insect pests. We observed an outbreak of flowers trips in most strawberry fields right in the middle of a hot and dry period that occurred between May 19 and May 25 (see photo above). Growers reported the damage and were able to control this outbreak in time to prevent further damage. Be alert and scout fields regularly to prevent trips damage in the future. Trips are a serious threat to fruit quality and quantity if left uncontrolled.

Sommer red raspberries and floricane raspberries are entering the early bloom stage. There are no reports of problems at this time and growth and development is proceeding without major challenges.

Blueberry growth and development in west central Michigan proceed without obstacles. Most varieties are in full bloom and early varieties are in the petal fall or fruit set stage. So far, the only major concern is fruitworm control. Cherry fruitworm started emerging and adults have been trapped at the MSU Trevor Nichols Research Center in Fennville, Michigan, and at farms around the Grand Junction-South Haven blueberry growing area. At those places, the biofix for running the cherry fruitworm degree day model in Enviroweather is May 29-30. Farms with captures on those dates need to prepare their pest control program to start spraying between June 9-10.

Since bees still are presents in most farms, avoid using harsh insecticides. Insecticides such as Dipel (Bacillus thuringiensis), Grandevo WDG and Venerate XC are good alternatives. These are organic recommended products. Please check the 2020 Michigan Fruit Management Guide (MSU Extension Bulletin 154) for doses and other recommended products.

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