Northwest Michigan fruit update – May 26, 2026
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EmailSummer conditions have finally hit northern Michigan. Honey bee activity is great for apple pollination.
Weather report
The weather seems to have finally turned in northern Michigan. After a slow start to spring, the temperatures are high for late May. Today, May 26, is predicted to hit 84 degrees Fahrenheit! Those highs are quite the departure from this spring’s temperatures when we were lucky to hit 50 F for a daytime high not that long ago! The weather literally switched to summer overnight. Growers will need to be on top of their management game with the change in conditions. We have accumulated 507.2 growing degree days (GDD) base 42 and 233.4 GDD base 50—quite a jump from last week. These numbers are behind our 36-year average: 521.8 GDD base 42 and 254.2 GDD base 50.
There is no rain in the forecast, so take a minute to breathe from disease control. We had some fog and wet weather over the holiday weekend, and most growers covered during that time. Watch the fire blight model with the warm weather and potential dew in the mornings.
Jeff Andresen’s forecast is predicted to be warm and dry on Tuesday and Wednesday, May 26-27. There are potential showers on Wednesday in the southeastern part of the state, and temperatures will cool on Thursday, May 29, followed by warmer conditions into the weekend. The medium range outlook is calling for drier than normal weather into early June with near to above normal mean temperatures. The updated longer-term forecast for the summer is predicting equal odds for temperature and precipitation.
Crop report
Crop development has moved quickly with the recent warm up. Tart cherry bloom came and went fast this year, and we are hoping that bees were able to work their magic quickly in the short pollination windows that we had this spring. We had small openings for pollination with warm weather, sunny conditions and no winds, so we are hoping those small timeframes were enough to get the pollination job done.
We are in late full bloom in Honeycrisp and Gala apples, and king bloom is starting to fall. Growers should be thinking about NAA applications for return bloom in Honeycrisp. Chayce Griffith, PhD, is recommending these treatments for growers to try:
- 10 ppm NAA at 30, 45, and 60 DAFB
- 150 ppm ABA at 30 DAFB
- 10 ppm NAA at 30, 45, and 60 DAFB + 150 ppm ABA at 30 DAFB (so NAA and ABA are tank- mixed at 30 DAFB)
Disease report
Apple scab. Growers should still be thinking about apple scab this week. According to the Northwest Michigan Horticulture Research Center Enviroweather station, we are at 96% spores matured and 70% spores that have been dispersed. Don’t give up yet, we are not done with primary scab. Something with a bit more translaminar activity is good for using now, and these materials will also be effective for powdery mildew.
Fire blight. Keep an eye on the fire blight model on Enviroweather this week. Although there is no rain in the forecast, the temperatures are high, and the fire blight bacteria will be growing fast under these conditions. Michigan State University Extension recommends an antibiotic spray this week because the epiphytic infection potential (EIP) is at 150 this afternoon, May 26. Even if no rain is in the forecast, dew or foggy conditions can wash bacteria down into the flower and cause an infection. Monitor the fire blight model closely as this model is based on degree hours rather than degree days, so the outputs can change quickly. The fire blight model is predicting a high EIP today, May 26.
Insect report
Insects are moving with the recent warm up. We caught our first codling moth at the research station this week. Codling moth management is based on biofix, and if we catch codling moth next week, we will set our biofix date for May 26. Male codling moths can be lured into traps baited with a synthetic pheromone blend. The first date of sustained captures of males in traps is used to set a biofix for the codling moth degree-day model, which uses accumulated degree-days for predicting key pest life stages and helps target the proper timing for management.
Setting the biofix for codling moth requires setting up a trap at the pink bud stage. The right lure depends on whether or not mating disruption products are being used to suppress codling moth. In orchard blocks that are not under mating disruption, the 1x lure can be used for both setting a biofix and monitoring for action thresholds. In orchard blocks that are under mating disruption, use a trap with a 10x lure to set your biofix, but then use the 1x lure when monitoring for thresholds. See this article from MSU Extension for managing codling moth in Michigan apple orchards.
Horticulture
Monitor orchards for Pro-Gibb in sweet cherry. Although we had a slow start to spring, our sweets at the station are ready for gibberellic acid (GA) application. MSU Extension recommends applying GA when leaves are five to seven expanded, which is now at the station. See this article from MSU Extension for using Pro-Gib in cherry to manage the crop.
This work is supported by the Crop Protection and Pest Management Program [grant no 2024-70006-43569] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.
