Southwest Michigan fruit update – June 3 2025
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EmailSurprise frost over the weekend and a heatwave beginning of this week—pure Michigan!
MSU fruit updates
Michigan State University Extension is in the process of filling the tree fruit specialist position based at the Southwest Michigan Research and Extension Center. Because of this, there will be a more abbreviated tree fruit section in our weekly updates until the position is filled.
We are also moving our weekly integrated pest management (IPM) updates to a virtual format and dividing them into tree fruit-specific meetings and small fruit-specific meetings. The small fruit weekly updates are held Tuesday evenings. Tree fruit weekly updates are held Wednesday afternoons. We are hoping to return to joint small and tree fruit updates next year. Thank you for your understanding and happy spring!
Weather
Last week was the second week in a row of cooler than average temperatures. Much of southwest Michigan stayed in the 60s for high temperatures. For a second week in a row, the region was also surprised by some late frosts. Surprise strong inversions early Sunday and Monday mornings brought some localized frost, damaging some crops in sensitive locations. Monday was also the beginning of a three-day heat spell for the region, with highs in the 80s and lows in the 60s all three days.
A line of rain has stalled over Lake Michigan on Tuesday, but will push through the region on Wednesday, leaving up to an inch of rain before passing east late in the day. The same storm system is predicted to rotate back into southwest Michigan on Friday, resulting in some light, scattered showers. We are expecting to see a cool down as the rain passes through the area on Wednesday, bringing low 70s to the region for the remainder of the week and weekend.
Last week was dry, save for a quarter inch of rain from a line of storms that passed through last Wednesday. But overall, southwest Michigan has seen average precipitation over the month of May. This is not enough to pull us out of the dry soils we have been seeing this spring. The U.S. Drought Monitor has designated the soils in southwest Michigan to be abnormally dry.https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?Midwest.
If Irrigation is available, now is the time to make sure the system is operational. Testing and repairing now will save emergency repairs if water shortages become more of a problem as we get into summer.
Tree fruit
Plum curculio oviposition is becoming more widespread. Neonicotinoids are recommended as oviposition deterrents as well as a general toxicant.
Apricots are close to full size. Pits hardening has not advanced in the last week, likely due to the cold weather.
Plums are continuing June drop, the self-thinning of the crop after fruit set.
Peach and nectarine continue to size. Some varieties are 0.75 inches or larger
Apple scab primary spore season is coming to an end. Codling moth and oriental fruit moth catches are lower than their peak a couple weeks ago, but higher than last week. This is likely due to the slightly higher temperatures during flight periods than last week. Expect trap catches to increase with increased egg laying this next week for codling moth.
Pears are also sizing as well. Some varieties are at 20 millimeters.
Small fruit
Grapes have not moved much in the past week. More varieties are close to 12 inches of growth with clusters separating and elongating. Brianna started blooming at the Southwest Michigan Research and Extension Center. Juice grapes and early hybrids are expected to bloom within the next week or so.
As we get close to bloom, this is when we shift our disease focus to black rot and other diseases that can impact fruit clusters. Except for powdery mildew, diseases that infect grapes in Michigan typically require rain events to disperse the spores. It only takes 0.1 inches of rain above 50 degrees Fahrenheit to trigger a possible infection.
Growers are scouting for wild grapes. Some growers reported the beginning of wild grape bloom last week, but those appear to be isolated situations. With the cool weather much of last week, we saw little development of wild grape bloom. Several locations began blooming over the last couple days. Wild grape bloom is used as a biofix for grape berry moth. Biofix is when 50% of clusters are at 50% bloom. See this Michigan State University Extension article for more information: Using the MSU Enviroweather grape berry moth model in 2018. As the Extension team continues to evaluate bloom this week, we may determine a regional biofix date for some time this week.
Blueberry green fruit have arrived. "Cranberry fruitworm continues to be caught, with an uptick in catches at the Trevor Nichols Research Center following the recent warm-up compared to the previous week. Sprays for cranberry fruitworm with residual action should be taking place soon if they haven’t already. Anthracnose risk continues to be low.
If you are a grower in Michigan and haven’t taken advantage of Michigan Blueberry Commission’s partnership with the Michigan State University Plant and Pest Diagnostics, keep it in mind as we progress through the season. This partnership allows every blueberry grower in Michigan to submit up to two samples to the Plant and Pest Diagnostics clinic for free! Follow this link for the submission form.
Strawberry harvest is under way. Several U-pick operations opened over the weekend, with healthy customer numbers with others planning to open later this week.
Brambles flowers are out and developing in summer bearing raspberries. Fall bearing varieties continue to grow.
Upcoming meetings
This year, in lieu of our historical Monday Night Fruit IPM Meetings, we will instead be hosting Tuesday night small fruit IPM meetings. They will take place entirely online at 5:30 p.m. starting April 1 and will occur weekly until June 24. Sign up here for the small fruit meetings.
The tree fruit IPM lunch meetings begin April 16. Sign up here for the tree fruit meetings.
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.
