The majority of sweet and tart cherry trees in the northwestern region, both varieties of which are past peak bloom, are chugging along as cold, and sometimes wet weather patterns are expected to continue through Memorial Day weekend.
Last week, the Northwest Michigan Horticulture Research Center (NWMHRC) reported that despite the weather forecast originally predicting more warm and dry conditions in May, temperatures have been cooler than normal by about 10-20 degrees. East Leland, for example, received 1.8 inches of rain between May 13-18, and was considered the wettest spot in Northern Michigan during that period.
Nikki Rothwell, MSU Extension specialist and NWMHRC coordinator, said while they still have honey bees around in the orchard, most of them are probably going out this week. Rothwell said cherry trees might have already had a chance at pollination depending on when they opened.
“We started blooming last week in both sweets and tarts and we had a six day window where temperatures were in the 70s to 80s, so bees will be happy about that,” Rothwell said. “It’s just all a matter of did the bee get there and was it active… so there’s all these factors we don’t know about, but we did have a warm window with open blooms, especially in our Bingham area.”
In the last couple of weeks, the state also experienced another weather phenomenon called a “cut-off low.” This unique occurrence is defined as “a low-pressure system that becomes detached from the main jet stream and can drift for days, causing persistent, often unsettled weather.” The systems can bring rain and thunderstorms and are known for being difficult to predict.
“We had this nice winter, and slow warm up to spring, but then we had a huge diversion in southwest versus northwest Michigan. There was almost a line across the state where they at one point were two weeks ahead and we were a week behind… So it’s not cold enough to cause damage, it’s just the fact that bees are not flying,” Rothwell said. “The other thing is that pollen tube growth is slow when temperatures are lower. Honey bees like to fly above 60 degrees and they don’t really like wind, they like sunshine.”
Cherries that do not receive adequate pollination fail to develop, making pollination an important part in growing quality cherries. Rothwell said at this point in time, it’s hard to tell if cherry crops will see a reduced harvest or if the honey bees were able to pollinate a tremendous amount during the warm days last week. The region could still see a good crop this year, she added, even if they had some frost/freeze damage from April 29 and 30. Honeycrisps were 80% in bloom at the Northwest Michigan Horticulture Research Center on Tuesday, so those varieties along with other fruit trees are affected and fall within the window of the recent cool weather patterns.
“Talking to our tart cherry breeder last week, she said you can lose up to 70% of Montmorency Tart cherries to frost or freeze, but if you get a good pollination window, you can still set a full crop, so there’s a lot of factors that are still up in the air,” she said. “The other thing we had commented on is just variability in bloom, so I have blossoms that have just opened in tart cherries and then I have some that have no petals left on them.”
Depending on your location in Leelanau County, cherry trees are at different points in the bloom process. Rothwell said in Bingham Township and the majority of the southern half of Leelanau, sweet and tart cherries are in the “petal fall” phase, but in some varieties of sweet cherries, she did report seeing some blossoms measuring about 3-5 millimeters in size.
“This is one of the faster (bloom) years. As soon as it got warm, they (the trees) just kind of moved through bloom really quickly,” she said. “Bloom will be over in tarts and it’ll be over in all tree fruit by next week — even in our farthest spot in Northport, there might be some later blooming apples, but a lot of it will be done in the county by next week.”
