Southwest Michigan fruit update – June 10, 2026
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EmailHigh temperatures and rain forecasted for this week means summer is here.
Chance of severe weather this week
Heat, rain and severe weather should be watched closely for the rest of this week. Northwest Indiana and southwest Michigan are in a heat advisory for Wednesday, June 10. Plan around warm conditions, monitor worker safety, and avoid pushing sensitive sprays into the hottest part of the day where possible. Thursday is the greater concern, with a stronger risk for thunderstorms capable of damaging wind and hail.
This weather pattern matters for orchard and vineyard management because storms can remove protective residues, create new infection periods, and cause fruit or foliage injury that changes disease risk. Check rainfastness, re-entry intervals and pre-harvest intervals before making applications ahead of storms. Where heavy rain occurs, blocks may need protection tightened afterward, especially for cherry leaf spot, brown rot-prone stone fruit, apple scab blocks with lesions and bacterial spot-susceptible peaches or plums.
After any severe weather, scout blocks for hail injury, wind damage, broken limbs, leaning young trees, fruit bruising, cracking and new wounds. Hail or wind-driven injury can quickly change the risk profile of a block, especially as cherries approach harvest and as peaches, nectarines and plums continue through cover sprays. Thursday’s forecast should be treated as the main weather disruption of the week.
You can track severe weather through the National Weather Service national risk outlook or through the regional National Weather Service forecast office for Grand Rapids.
Tree fruit
Apricot trees have medium fruit in central Berrien and Van Buren counties, with an average fruit size of 28 millimeters (mm). As fruit begin ripening over the next few weeks, controlling brown rot becomes the key disease management priority. Conditions across the next week will be hot and humid with many wetting events, the perfect conditions for brown rot development. Keeping coverage is key.
Maintain strong brown rot protection as fruit soften and color. SI fungicides generally provide excellent brown rot control, but keep in mind the rotation and resistance management when choosing a product. As harvest nears, check the pre-harvest interval of any applied products. High temperatures this and next week are expected to hasten ripening and development.
Peaches and nectarines continue to size in southwest Michigan, with most cultivars now moving beyond the small-fruit stage and into pit hardening. Plum curculio pressure is low this week, as most development has already occurred. If you’re still finding fresh oviposition scars, select an insecticide that emphasizes rapid knockdown of immigrating adults and enough residual activity to protect exposed fruit.
For growers dealing with a reduced peach crop this season, a new bulletin from Michigan State University Extension is available that outlines best practices for managing trees when crop load is low. “Best Practices for Peach Orchards with Reduced Crop Load” covers how to adjust fertility, pruning, pest and disease management, and other in-season decisions so that trees remain healthy and productive for next year.
During the cover-spray period in peaches and nectarines, the program can settle into a more protective, maintenance phase. Fruit are still firm, so brown rot is usually a lower priority for the next few weeks, before fruit begin to soften near harvest. For now, the main goal is to keep steady cover on fruit and foliage for scab, anthracnose, green fruit rot and bacterial spot-prone blocks using materials like captan and sulfur rotations where appropriate. The more intensive brown rot program becomes important later, as fruit ripen and become more susceptible.
Lesser peachtree borer flight is declining, with fewer adults caught this week than last, suggesting the main control window is coming to an end. High-risk peach and cherry blocks should still be watched carefully, especially where trees have Cytospora cankers, winter injury, pruning wounds, mechanical damage, weak scaffold crotches or a history of borer infestation. Young trees remain especially vulnerable because even limited feeding injury can affect a large proportion of the trunk or scaffold area.
At this point, treatment decisions should be based on continued trap captures, block history, and visible risk factors rather than routine calendar sprays. Where control is still justified, sprays need to be directed to the trunk, scaffold limbs and wounded or cankered bark since larvae tunnel beneath the bark soon after hatch and are difficult to reach once established. Avoid treating only the outer canopy. Rotate product choices by IRAC group where possible, and check the labels carefully for crop, timing, rate and pre-harvest restrictions.
Plums are around 19 mm and are in the cover-spray period. This is mostly a maintenance window: keep protective coverage on fruit and foliage, especially where plum curculio, scab/fruit spots or bacterial spot-susceptible Japanese plum cultivars are a concern. Brown rot generally becomes more important later as fruit soften, or sooner if fruit are wounded by insects, hail, cracking or other injury. Lesser peachtree borer can also affect plums, particularly in injured or cankered trees, but declining flight suggests the main control window is winding down.
Tart and sweet cherry fruit continue to size rapidly across Berrien and Van Buren counties, with average fruit size near 14 mm in tart cherry and 18 mm in sweet cherry. As tart cherry harvest approaches, shift management efforts toward preharvest priorities, including protecting fruit quality, keeping leaves functional, managing insect contamination risk and maintaining enough flexibility for weather or harvest delays.
Cherry leaf spot remains the main disease concern in tart cherries. Even where pressure has been limited so far, protection should continue through warm, wet periods to prevent early defoliation and protect return bloom and crop potential for next year. Fungicide programs at this timing can still include FRAC 3, 7, 11 and M04 materials, with attention to resistance management, rainfastness and pre-harvest intervals.
Brown rot and spotted wing Drosophila are becoming more important as fruit color and soften. Risk can increase quickly after warm rain, cracking, bird injury or delayed harvest, even if trap captures or visible disease pressure are still low. Tighten coverage and spray intervals as harvest windows get closer, especially in blocks with a history of brown rot, spotted wing Drosophila pressure, cracking or uneven ripening.
Apple fruits are sizing across the region and are generally between 22 and 35 mm. Primary apple scab spore release is finished, marking the end of the primary scab period. Blocks that stayed clean through primary scab should now be moving into a lower-risk period. However, blocks with visible lesions can still produce secondary scab infections that spread to fruit and foliage during wetting events. Where conditions are marginal, the MSU Enviroweather apple scab model remains useful for identifying infection periods and refining spray timing.
Powdery mildew risk is low this week.
Captan does not provide powdery mildew control, so captan cover sprays alone are not sufficient where mildew is active or susceptible cultivars are present. QoI, SDHI and SI fungicides provide stronger mildew activity. For resistance management, tank-mix these materials with a protectant fungicide, such as an EBDC, where labels and crop stage allow.
Codling moth management should now be based on local biofix and accumulated degree days, with product choice matched to the life stage being targeted. Egg-focused programs are timed earlier, around biofix plus 100 degree-days (DD), while larvicides are aimed at the egg hatch period beginning at biofix plus 200 to 250 DD. For much of southwest Michigan, we are in the larvicidal window through the end of the week.
In higher-pressure blocks, early ovicidal timing, such as an application made last week, should be followed by larvicidal coverage as hatch begins. In lower-pressure blocks, the first larvicide may be delayed closer to 350 DD, with follow-up applications based on trap counts, fresh injury and block history. After treatment is applied, reset cumulative trap counts so additional decisions reflect new moth activity rather than pressure that has already been addressed.
Codling moth programs should rotate modes of action across generations. A practical approach is to keep one chemical class within the first generation, then switch to a different class for the second generation. Premix products require extra attention because they may contain more than one active-ingredient class. Larval-targeting materials, including diamides, spinosyns, neonicotinoids, avermectins, granulosis virus products and other labeled options, depend heavily on timing, ingestion and good coverage before larvae enter the fruit. Pyrethroids and organophosphates are generally poor fit choices at this point because of resistance concerns and the risk of disrupting mites and beneficial insects.
Pear fruit are sizing across southwest Michigan, with many blocks now in the 25 to 35 mm diameter range. Plum curculio activity has largely ended. Fresh injury should still be noted if found but shift your management attention toward pests and diseases that can continue building through early summer.
Primary pear scab risk has also largely ended now that primary spore discharge is complete. Blocks that remained clean through the primary scab period can begin moving into a lower-risk phase. However, continue watching blocks with visible lesions for secondary scab. If lesions are present, secondary infections can still develop during wetting events and may continue to threaten fruit and foliage.
Pear psylla should be the main insect focus moving forward, especially in blocks with a history of pressure. Summer populations can build quickly on new shoot growth, and management is much easier before colonies become well established. Scout for adults, eggs and young nymphs, and pay close attention to honeydew development, which can lead to fruit marking and sooty mold later if populations are allowed to build.
Continue general scouting for lingering injury from tarnished plant bug, green fruitworm and early leafroller feeding. These pests should now be secondary concerns compared with pear psylla and any active secondary scab risk.
Small fruit
Early grape hybrids are post-bloom. Juice grapes with primaries are in bloom or post-bloom. Winegrape bloom should occur in a week or so depending on how this heat impacts the crop. Growers are thinking about grape berry moth control. Tumid gallmaker has been observed. Rose chafer and Japanese beetle are emerging soon.
Blueberries are growing! Damage from flower thrips has been observed in various fields across the region. Monitoring for cherry fruitworm and cranberry fruitworm is in progress. Cranberry fruitworm was caught at the Trevor Nichols Research Center and they are setting the biofix for May 16-17. Both insects have had a decreased trap count at the Trevor Nichols Research Center since last week.
Traps should already be put out for blueberry maggot. None have been caught at the Trevor Nichols Research Center.
Spotted wing Drosophila are being caught at the Trevor Nichols Research Center with catch counts increasing. Make sure your irrigation systems are up and running, especially if you primarily rely on drip. We are likely going to have a drier summer. Japanese beetles should be emerging soon. This is a great time of year to walk the fields and scout for viruses.
Blueberry harvest will be here before we know it. Join the MSU Extension blueberry team online on June 17 for a blueberry pre-harvest webinar. Register today.
Strawberries are being harvested. Growers are focused on controlling leaf spot, preventing fruit rots and picking berries. There may be increased disease pressure and difficulty harvesting with the rain expected in the forecast. Many growers are reporting root rot problems. Some growers are finding thrips damage on their fruit. Thrips damage in strawberries looks like bronzing with extra seediness.
Brambles flowers are beginning to show. Growers are controlling powdery mildew and raspberry sawfly. Raspberry borer has been observed in fields in VanBuren County.
Upcoming meetings
The Strawberry Field Day is taking place July 8 in Three Rivers, Michigan. Sign up to attend.
The Blueberry Pre-harvest Webinar will be held online on June 17. Sign up to attend.
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.
