Northwest Michigan fruit update – May 7, 2024
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EmailTart cherries are in full bloom and sweets are starting to drop their petals. Gala are at 15% bloom and Honeycrisp are at king bloom. We have had excellent pollination weather for the last three days and black stem borer is in peak flight.
Weather report
The weather has been beautiful across the region. With sweet and tart cherries in bloom, this sunshine and warm weather is perfect for pollination. Over the weekend, we had daytime temperatures top out at 72 degrees Fahrenheit on Saturday, May 4. Today, May 7, is predicted to be the warmest day of the week with daytime highs near 70 F. After today, a cold front moves in, and the highs for the remainder of the week are only in the mid-50s to 60 F.
There is rain in the forecast starting this evening. Jeff Andresen predicts severe weather this evening, but most of this concerning weather will be in the most southerly part of Michigan or it will not even make it into the state, staying in Ohio and Indiana. Wednesday, May 8, will be dry and cooler, and rain is forecasted to move back into the state Thursday into Friday. There will still be a chance for scattered showers through the weekend. Warm weather is predicted for the latter half of May. According to Andresen, there is a bit more noise in the medium range forecast for predicting weather.
We have accumulated 374 growing degree-days (GDD) base 42 and 147 GDD base 50 for 2024. We are still well ahead of our long-term average: 265 GDD base 42 and 114 GDD base 50. We were at full bloom in sweet cherry yesterday, but petals are beginning to drop today. Tarts are also in full bloom here at the Northwest Michigan Horticulture Research Center. Both cherries are in bloom at the same time, so we anticipate a busy harvest season for these crops that will likely ripen at a similar time.
Crop report
The following growth stages were evaluated at the Northwest Michigan Horticulture Research Center yesterday afternoon, May 6:
- Balaton – full bloom
- Bartlett Pear – full bloom
- Montmorency – full bloom
- Potomac Pear – full bloom
- Emperor Francis – petal fall
- Gold – petal fall
- Ulster – petal fall
- Riesling – bud swell
- Gala – 15% bloom
- Honeycrisp – king bloom
As mentioned above, pollination weather has been excellent for the past few days, and cherries should have had adequate time for bees to work their magic. Bee activity has been strong in the hives at the Northwest Michigan Horticulture Research Center. There are ample bees in the blooming canopies during the warmer hours of the day.
We are starting to see bloom in apples as well. Gala are ahead of Honeycrisp, and we are seeing a good number of flowers on trees at the research center. We have also heard of good bloom in apples across the region, which is notable as we have had back-to-back big apple crops in the state for the last two years. Pears are also blooming at the Northwest Michigan Horticulture Research Center.
We have had isolated reports of damage in both sweet and tart cherry but mostly in lower sites within an orchard. We have found little damage to most crops here at the station.
Pest report
Honey bees will forage at temperatures of 65 F or warmer. Bumble bees and solitary bees will forage at temperatures 5-10 degrees cooler than honey bees. During bloom, growers are encouraged to implement practices that minimize pesticide exposure to bees by using reduced risk pesticides and spraying at times when pollinators are not active. Find tips and guidelines to minimize bee pesticide exposure.
Apple scab
Primary apple scab season continues. Trees will need to be protected ahead of wetting events. The cooler weather this weekend will slow down maturation and germination of spores. Cover trees if the RIMpro infection value exceeds “Slight infection risk.” An infection event is expected for all three weather stations below on May 8 and May 15 based on the current weather forecasts.
RIMpro links:
American brown rot
Many sweet cherries are past bloom and the cooler weather coming this weekend will not be conducive for growth and infection of American brown rot.
Cherry leaf spot
Tart cherries are in full bloom and bract leaves fully expanded. Wetting events will put these leaves at risk for cherry leafspot primary infection. There is a threat of rain nearly daily due to the active weather pattern currently over the state. Enviroweather is reporting an infection event that occurred from May 2 – 3 at the Northwest Michigan Horticulture Research Center and most weather stations in the northwest region.
European brown rot
With tarts in full bloom and cool weather with rain in the forecast, we could see blossom infection of European brown rot. Blossom infection may occur from 30 to low 50 F with rain or a high relative humidity. Temperatures this weekend are not expected to make it out of the 50s and lows will be in the 40s. Balatons and trees in low spots, near woods, near windbreaks or in other areas with slow-drying conditions are particularly susceptible to this pathogen.
Fire blight
Many apple varieties are beginning to flower in the area and could be infected by fire blight if weather conditions are right. The Enviroweather fire blight model can be used to assess infection risk potential by choosing your closest weather station and entering date of full bloom. Disease management is recommended if the epiphytic infection potential (EIP) exceeds 70.
Powdery mildew
Powdery mildew was severe in many apple and cherry orchards in 2023 and inoculum levels are expected to be high this year. Managing this disease will become critical if warm and dry conditions return after petal fall. Emerging leaves from buds infected last season will begin to produce conidia and result in an early secondary infection period. The prevailing temperatures for the week are too low for infection; its sporulation and growth are favored by temperatures of 68 to 81 F.
American plum borer
An average of 2.3 American plum borer were caught this week at the Northwest Michigan Horticulture Research Center.
Black stem borer
An average of 26 black stem borer were trapped this week at the Northwest Michigan Horticulture Research Center, a major jump from last week, and many were still alive when traps were checked yesterday (May 6). We believe this indicates we are in peak flight for females. This is the best opportunity to manage this pest.
Coddling moth
No codling moth were caught this week at the Northwest Michigan Horticulture Research Center. First catch of codling moth were reported at the Trevor Nichols Research Center in Fennville, Michigan, on May 6.
Green fruitworm
An average of 27 green fruitworm were caught at the Northwest Michigan Horticulture Research Center.
Oriental fruit moth
No oriental fruit moth were caught this week at the Northwest Michigan Horticulture Research Center. First catch of oriental fruit moth were reported at the Trevor Nichols Research Center in Fennville on April 15.
San Jose scale
No San Jose scale have been trapped at the Northwest Michigan Horticulture Research Center.
Spotted tentiform leafminer
An average of 117 spotted tentiform leafminer were trapped at the Northwest Michigan Horticulture Research Center.
