Southwest Michigan fruit update – April 29, 2026
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EmailKeep an eye on crop phenology as incoming weather cools down.
MSU fruit updates
Happy spring! If you haven’t signed up to come to the Tuesday night South Michigan Fruit IPM meetings, sign up now.
Tree fruit
Apricot trees have small fruit forming in central Berrien and Van Buren counties, with an average of 5 mm fruit, although much of the crop was lost through spring frost. Surviving fruitlets are sizing rapidly. Controlling plum curculio now prevents unmarketable fruit later in the season. The first catches of plum curculio occurred last week in Berrien County.
Peaches and nectarines are done blooming in southwest Michigan. During post-bloom, make note of the remaining fruit set before making any thinning decisions.
Brown rot protection is critical during bloom and after, particularly under warm, wet conditions, so maintain tight spray intervals (around three to five days) when weather favors infection, prioritize high-efficacy materials with rotation among FRAC groups, and ensure applications are made ahead of rainfall events with strong coverage throughout the canopy. Brown rot pressure is expected to be low for the upcoming week, as temperatures will remain lower than necessary for fast disease progression.
In blocks that experienced bud loss, some natural thinning is already occurring, which may reduce the need for aggressive thinning later, but variability within trees and across blocks is likely to be significant. Focus on early, block-specific assessments rather than assuming uniform set, and avoid making aggressive thinning decisions until actual fruit retention is clear. This season in particular will require adjusting strategy based on observed conditions rather than bloom intensity alone.
Plum curculio has been caught in Berrien, Van Buren and Allegan counties. Insecticide selection for plum curculio at petal fall should prioritize rapid knockdown of immigrating adults combined with enough residual activity to protect newly exposed fruit during the oviposition window. Broad-spectrum materials with strong efficacy on plum curculio, such as Imidan 70 WP, Avaunt 30 WG, Voliam Flexi or Besiege, provide the most consistent control and are well suited for blocks with confirmed activity. Pyrethroids including Warrior II, Mustang Maxx and Baythroid XL can be highly effective during warm periods of active movement due to their fast knockdown, though their shorter residual and impact on beneficials should be considered. Neonicotinoids like Assail 30 SG or Actara 25 WG offer additional activity but generally require higher rates or tank-mix support for reliable plum curculio control.
In all cases, product choice should be paired with tight application timing at petal fall and follow-up coverage based on temperature-driven activity, since protection must be present before egglaying occurs to prevent irreversible fruit injury.
Plum fruit are now pushing out of the shuck in both Japanese and European types, entering a stage where the crop becomes directly exposed to pest pressure. As the cuticle develops and fruit begin to size, they become attractive targets for plum curculio egglaying and plant bug feeding, while also becoming increasingly susceptible to brown rot and bacterial spot under favorable weather. This period marks a shift from protecting blooms to protecting fruit, where even brief lapses in coverage can result in permanent damage.
Management should focus on maintaining a consistent protective program, timing insecticides with periods of pest activity and keeping fungicide coverage ahead of rain events to limit infection during early fruit development. More information on American brown rot can be found in this MSU Extension article.
In cherries, tart cherries and sweet cherries are in petal fall in Berrien and Van Buren counties.
This is a critical window for brown rot control, particularly under warm, wet conditions. Time applications ahead of rain events with effective materials and good canopy coverage.
At the same time, petal fall signals the beginning of meaningful insect pressure as fruit become exposed. Plum curculio, obliquebanded leafroller, green fruitworm and tarnished plant bug can all contribute to early fruit injury, with feeding and oviposition occurring shortly after petal fall.
Management should focus on a well-timed insecticide application targeting this transition, with products that provide both knockdown of active insects and residual protection as new fruit tissue develops. Broad-spectrum materials such as Imidan 70 WP, Avaunt 30 WG, Voliam Flexi or Besiege offer strong control across multiple pests, while pyrethroids like Warrior II or Mustang Maxx provide rapid knockdown during periods of active movement. Softer materials such as Surround WP or Entrust can be used in constrained systems but require tighter intervals and excellent coverage. As with disease management, timing is critical; applications should align with pest activity and environmental conditions to prevent early-season injury that cannot be corrected later.
Most apple varieties are in full bloom. Smitten, Zestar! and early Fuji are at the end of bloom and fruit are setting, while Honeycrisp, Cameo and Fuji entered full bloom over the weekend. Low temperatures during bloom may reduce pollination. The cool weather over the past week has increased the difficulty of pollination as bees are less active. Additional strategies for increasing pollinator activity in apple orchards is available in this Penn State article.
Apple scab risk is still low over the next several days. While risk is low, maintaining adequate fungicide protection is important to stop the spread of disease during wetting events. Copper should be avoided beyond half-inch green to reduce the risk of fruit russeting. SDHI fungicides are excellent choices to control primary scab. The MSU Enviroweather apple scab model can be used to track infection periods and better time applications.
During bloom, managing fire blight becomes the main concern. To effectively manage fire blight, using antibiotic applications is necessary during bloom when infection risk is high. Proper timing and coverage are critical, as these materials work by suppressing bacterial populations on open blossoms before infection occurs. Detailed guidance on using streptomycin, Kasumin and oxytetracycline including rates, timing and resistance management can be found in this MSU Extension article. Wetting events forecasted for the next few days in combination with high temperatures make apple fire blight a concern.
Avoid using insecticides during this period to protect pollinators. Honey bees and other pollinators are actively foraging in orchards, and insecticide exposure at this stage can significantly reduce pollination efficiency and colony health. Even materials considered “softer” can pose risk when applied during active bloom, particularly if they contact open flowers or are applied during daylight hours. Delay insect management until petal fall, when pollinator activity has ceased and fruit are no longer dependent on insect visitation for set.
Pears are in late petal fall across Berrien and Van Buren counties, marking the transition from bloom protection to early fruit management. As petals drop and fruit become exposed, susceptibility to both disease and insect injury increases. This is a key window for pear scab, particularly under periods of rainfall or extended leaf wetness. Fungicide programs should remain active and well-timed ahead of precipitation to prevent infections from establishing that can carry through the season. Maintaining thorough coverage is especially important as canopy density begins to increase and new tissue continues to emerge.
Insect activity also becomes more relevant at this stage, with pests such as plum curculio and tarnished plant bug posing a risk to newly set fruit. Feeding and oviposition can begin shortly after petal fall, leading to early fruit deformities or drop. Timely insecticide applications may be warranted where pressure is present, with product selection balancing efficacy against target pests and preservation of beneficial organisms.
Small fruit
Juice grapes and early hybrids are at full bud break with first leaves starting to fold out. Other hybrids and early vinifera varieties have opened. The disease focus now is on phomopsis, black rot, anthracnose and powdery mildew. Once leaf tissue is visible, contact fungicides that include broad-spectrum/contact fungicides like the EBDCs (FRAC M3) and captan are effective and function similar to dormant applications by sanitizing the vineyard before bloom. The first grape berry moths have been caught. The first catch is the suicidal males, and we are still watching out for wild grape bloom.
Blueberry are at early pink bud through southern Allegan County. Blooms are out in Van Buren County with many early varieties nearing full bloom. These early varieties are showing frost damage (show frost blueberry picture here). With bees out and about, it’s important to keep pollinators in mind while spraying.
Mummy berry is the next pathogen to manage. Bloom is imminent, and once flowers are out, we will be thinking about flower thrips and beginning to monitor other insects. Monitoring for cherry fruitworm and cranberry fruitworm has begun. Blueberry gall midge, a minor pest that damages growing tips, should be emerging in the next week or so.
Fertilization typically begins around bloom which is fast approaching. Make sure your irrigation systems are up and running. The frost-free date for most of Michigan is the middle of May, so it's good to be prepared for potential frost protection between now and then.
Strawberry flowers are out. Critical temperatures for strawberries are 10 F when they’re in the ground and 20 F when they’re out of the ground. Keep an eye on the phenology of your strawberries. The official frost-free date for southern Michigan is in the middle of May and we have cold weather coming this weekend. Check out this article from the University of Minnesota for more information about protecting your strawberries from frost.
Growers are looking at early season herbicides to control overwintering weeds. When selecting an herbicide, check the preharvest interval (PHI). We are getting to the part of spring where some herbicide PHIs are cutting it close to predicted harvest dates.
Brambles leaves are emerging.
Upcoming meetings
This year, we are hosting Tuesday Night Fruit IPM meetings. They take place in person at the Southwest Michigan Research and Extension Center in Benton Harbor and online via Zoom. The meetings cover phenology, insect and disease progression and selected topics from experts in Extension. These meetings cover small fruit for southwest Michigan and tree fruit for southwest and southeast Michigan. The meetings start at 5:30 p.m. and occur weekly until June 24. Sign up for the online option. Past meeting recordings are available online via MSU Mediaspace.
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.
