Michigan State University Extension reported on May 6 that cold weather continues to affect northwest Michigan, with temperatures remaining low and frosty nights predicted for the week. According to the update, daytime highs have fluctuated, with a notable low of 28.7 degrees Fahrenheit recorded at the Northwest Michigan Horticulture Research Center and even colder readings in other parts of the region.
The persistent cold is slowing crop development across northern Michigan. The report states that sweet cherry varieties are showing variable damage from recent frosts, while tart cherries appear worse than after earlier freeze events. Despite this, viable flowers remain in most blocks, leading growers to hope for sufficient pollination if warmer weather arrives soon.
Crop progress has been slow due to these conditions. Sweet cherries are just starting to open in some areas, but cool temperatures are limiting honey bee activity necessary for pollination. The report also notes that Gala apples are at late tight cluster stage and Honeycrisp apples remain at tight cluster. In southwest Michigan, there is some damage noted in juice and wine grapes resulting in expectations of a lighter crop for 2026; however, apple crops look good overall.
Disease management remains a focus as apple scab is currently considered the primary threat due to early-stage growth and limited rainfall forecasted for the coming days. Growers are advised that if rain returns alongside warmer temperatures, increased vigilance will be needed against both apple scab and American brown rot infections during bloom periods.
Insect activity has remained low under these cool conditions. The update mentions green fruitworm presence again this week along with one black stem borer captured at the research center. With reduced bee activity anticipated due to ongoing cold weather—and fewer viable flowers—growers may consider increasing hive numbers per acre or relying more on native pollinators which can operate at lower temperatures.
Horticultural recommendations include considering ReTain applications for sweet cherry growers aiming to extend flower viability under poor pollinating conditions such as wet or windy weather or when bee activity is limited by temperature. ReTain works best when applied early before significant bloom progression but only activates above 60 degrees Fahrenheit.
Michigan State University Extension Agriculture addresses challenges in food systems, health issues, and environmental concerns through education and outreach efforts statewide; it operates major research centers across every county while collaborating with AgBioResearch scientists from eight university colleges according to the official website.
