Southwest Michigan fruit update – May 20, 2025
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EmailBloom is cooling off, as is the rest of the state.
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 started warm. Southwest Michigan saw temperatures close to 80 degrees Fahrenheit for much of the week. A line of severe thunderstorms caused localized damage to structures and downed trees throughout the region on Thursday, May 15, and resulted in a quarter to an inch of rain. A cold front brought cooler, drier air on Saturday. The temperatures have stayed near 60 F through today, May 20.
Another rain system entered the region Tuesday morning. Another round of scattered showers are expected on Wednesday, May 21. Temperatures should stay in the upper 50s or 60s for the rest of the week before some mild warming early next week.
Tree fruit
Oriental fruit moth and codling moth catches continue. Biofix for oriental fruit moth was the end of April. Codling moth biofix was likely early last week. Plum curculio damage is now being seen.
Cherries are at shuck split. Some varieties are at 7-8 millimeters (mm).
Plums are out of the shuck. Plums are also more vulnerable to plum curculio and tarnished plant bug once they emerge and the fruit is noticeable. Control of black knot begins at petal fall. Fungicides in combination with pruning out the knots is important for this disease.
Peach and nectarine are out of the shuck. Some varieties are up to 14 mm.
Apple are beginning to size. Zestar at the southwest Michigan Research and Extension Center are about 20 mm. Thinning sprays at this time 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. Protectants are preferred over systemic fungicides at this time of year for scab control.
Pears are also beginning to show fruitlets. As with apples, scab sprays are needed as green tissue emerges if we see any precipitation over the next week.
Small fruit
Grapes are at close to 12 inches of growth with clusters separating and elongating. With the cool weather, we are still more than a week before bloom. Some slower hybrids and early vinifera are around 6 inches of growth.
Early season sprays target phomopsis on the developing shoots. Several broad-spectrum fungicides are effective against this disease. Mancozeb is a popular choice this time of year.
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. 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.
Blueberry bloom is finishing up. Bluecrop is finishing up petal fall in Berrien County. Cranberry fruitworm moths are being caught in traps. This past week, there was a substantial increase in cranberry fruitworm caught in traps at the Trevor Nichols Research Center. Normally this would signal to start spraying for control, but with the cool week coming, there will be slow GDD accumulation with around 24 GDD base 50 over the next week predicted. This means that the 80-100 GDDs needed for cranberry fruitworm will take longer than usual and sprays should most likely wait until 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 with something like Assail, Delegate or entrust. As always, make sure and consult the label before application. More information can be found in the “Michigan Fruit Management Guide.”
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. Early locations have fruit beginning 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.
Brambles flowers are being found on summer bearing raspberries. Fall bearing varieties are up to 2 feet of growth.
Surveys
Please fill out this survey from our colleagues across the Midwest about novel weed sprays!
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.
Want to learn more about Bulletins Live Two? Join Jackie Perkins and Cheyenne Sloan on May 22 at one of two webinars to learn more. For more information and the link to sign up, check out this article.
