Southwest Michigan fruit update – May 27, 2025
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EmailLast week was cool, so there wasn’t much movement.
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 cool. Much of southwest Michigan stayed in the 50s for high temperatures most of last week. A surprise calm spell early Saturday morning, May 24, brought some localized frost, damaging some crops in sensitive locations. Coincidentally, Saturday was also the beginning of a slow warming trend we are expecting to see continue through this week. The region saw 60s over the weekend with some locations hitting 70 degrees Fahrenheit. These temperatures should continue with another upward push to 80 degrees by the start of next week.
Southwest Michigan has seen average precipitation over the past month. This continued over the past week with some storm systems passing through the area on Tuesday and Wednesday but no precipitation for the rest of the week. Weekly rain totals are near 1 inch. This next week will be drier yet. A storm front is expected to push through the area on Wednesday afternoon, bringing about a quarter inch. No significant chances of rain are predicted for the next seven to 10 days.
The U.S. Drought Monitor has designated the soils in southwest Michigan as being abnormally dry for much of the winter, continuing to the most recent report late last week.
Tree fruit
Plum curculio oviposition is underway. Neonicotinoids are recommended as oviposition deterrents as well as a general toxicant at this time.
Apricots are close to full size. Pits are hardening.
Plums are beginning June drop, the self-thinning of the crop after fruit set.
Peach and nectarine continue to size. Some varieties are 0.75 inches.
Apples are beginning to size. Zestar at the Southwest Michigan Research and Extension Center are at about an inch. Thinning sprays are critical for fruit load management and sizing at harvest. Apple scab spores are still being caught. Scab sprays may be needed to protect the green tissue as it continues to emerge.
Pears are also sizing. Some varieties are at 15 millimeters (mm). As with apples, scab sprays are needed as green tissue emerges if we see any precipitation over the next week.
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 have started blooming at the Southwest Michigan Research and Extension Center. Most other early varieties appear to be a week or so from bloom.
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. With the exception of 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 F to trigger a possible infection.
Growers are beginning to scout wild grapes. We are a week or more from wild grape bloom but locating the vines so you can regularly check them in the coming weeks should be performed soon. Some growers are reporting the beginning of wild grape bloom. 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. With the weather coming up and the early reports coming in, expect biofix some time over the next week.
Blueberry bloom is finishing up. Bluecrop is finishing up petal fall in Berrien County. Last week, cranberry fruitworm moths were being caught in traps. This past week, there was a substantial decrease in cranberry fruitworm caught in traps at the Trevor Nichols Research Center. The cool week that just passed slowed growing degree day (GDD) accumulation. This means that the 80-100 GDDs needed for cranberry fruitworm will take longer than usual and sprays should most likely wait until later this week or early June.
Flower thrips have been seen in elevated number this year, much like last. You can check for thrips by walking through your field, selecting five to 10 random flower clusters and shaking them over your phone screen to look for the small, slow moving yellow thrips. If you find them in most of your clusters, consider spraying for them with something like Assail, Delegate or entrust.
As always, make sure and consult the label before application and more information can be found in E154. With bloom wrapping up, if you apply granular fertilizer, it’s almost time for the second split application. Split applications are recommended since it helps spread out the “food” for your blueberries instead of feeding them one big meal all at once.
Strawberry bloom continues. Fruit are continuing to size.
Irrigation for frost can make it so that fungicides have a hard time sticking. If sprays are needed, use systemic options and treat early in the morning for the most time for the plant to absorb the fungicide before the next watering. With bloom and bee activity, do not use insecticides.
Cool, wet conditions can favor angular leaf spot, a bacterial disease. The only effective bacterial controls are copper formulations. Growers are looking at early season herbicides to control overwintering weeds and have begun spreading straw. When selecting an herbicide, check the preharvest interval.
Bramble flowers are being found on summer bearing raspberries. Fall bearing varieties are up to 2 feet of growth.
Surveys
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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.
