Southwest Michigan fruit update – June 11, 2024

Some fruits are beginning to show color.

A cluster of blueberries at varying degrees of ripeness.
Early blueberry varieties are starting to look blue. Photo by Cheyenne Sloan, MSU Extension.


This week is expected to be drier than normal, starting out cool and heating up by the end of the week. This upcoming weather will be sunny and warm with low humidity, which means water needs will be elevated for this week. This dry weather will be good for disease control but keep an eye on your water needs this week. 

Southwest Michigan GDD summary from March 1 – June 10, 2024 


GDD 42 F 

GDD 45 F 

GDD 50 F 

Benton Harbor (SWMREC) 




Lawton (Lawton) 




Fennville (TNRC) 




Grand Junction 




Average for the SW region 




A weather report by Michigan State University meteorologist Jeff Andresen is available online.  

Tree fruit 

San Jose scale crawlers have been active for more than a week in southwest Michigan. This first generation is easier to control than the second and third because the later generations are more spread out and treatment options are fewer closer to harvest. The best brown rot fungicide options close to harvest for stone fruit are the SDHI fungicides Miravis and Merivon, and the second generation DMI Cevya.  

Peach and nectarine predicted harvest dates in southwest Michigan are about five days earlier than normal (e.g., July 26 for Red Haven in central Berrien County). Pits are still soft. Protection against plum curculio and tarnished plant bug is still needed if there is a crop. Trap catches of oriental fruit moth indicates first generation flight is over. The next generation flight should start soon, and larvae from this brood targets fruit.  

The need for rusty spot spray coverage ends with pit hardening. The Trevor Nichols Research Center trap line has recorded moth catches for lesser and greater peachtree borers for the past month. Assail trunk sprays and pheromone disruption are the strategies for managing lesser and greater peachtree borers with the unavailability of Lorsban.  

Peach showing ragged tearing caused by the insect tarnished plant bug. Photo by Bill Shane, MSU Extension. 

Cherry harvest of early season sweet cherry varieties has started. Montmorency cherry shaking harvest is scheduled to begin June 24 in Berrien County, one of the earliest starts in recent years. Ethrel treatment for loosening fruit for shaking generally goes on seven to 14 days prior to anticipated harvest. Brown rot and cherry leaf spot control are the primary disease management concerns now. The early harvest should help to avoid fruit infestations by spotted wing drosophila fly larvae. 

Apple fruit are sizing rapidly. Primary scab season is over based on trap catches. Calcium treatment for suppressing bitter pit should be ongoing for susceptible varieties. Bitter pit tends to be more severe on light crop years, especially where soil reserves of potassium are high. Symptoms for sooty blotch and flyspeck are expected to start showing up in a few weeks. Protection against codling moth larvae should be ongoing. Oriental fruit moth trap catches are expected to increase with the start of the second generation flight. Apple maggot will start to be a concern in the next few weeks for sandy sites, particularly for early ripening summer varieties. 

Pear hand thinning is underway. Primary scab season is over. Pear psylla is causing gumming and sooty symptoms on fruit and leaves in some orchards. Ziram is sometimes used as a protectant fungicide substitute for captan, which is not labeled on pears before harvest. Ziram can cause russeting of Harrow Sweet pears when applied to young fruit. 

Small fruit 

Grape bloom on primary shoots is almost complete. Some advanced hybrids such as Marquette and Brianna are at buckshot berry in some areas. Some vinifera are still finishing bloom on primaries. Juice grapes and hybrids are blooming on secondaries now. Vinifera secondaries are generally a week away from bloom.  

Phomopsis continues to be found in southwest Michigan. Black rot is also showing up more in the past week. This next week should be dry, but with humidity expected some mornings and bloom still in the vineyards, disease coverage is still important.  

20240611_Marquette buckshot.jpg
A Marquette grape cluster at the Southwest Michigan Research and Extension Center. Photo by Michael Reinke, MSU Extension. 

Blueberry fruit is sizing with earlier varieties showing hints of blue. Fruit set looks good. Some farms are reporting poor foliage growth on Bluecrop and other varieties. The cause is unknown so far. Draper drop has been affecting growers across the region. Disease focus should be on early fruit rot management. Cranberry fruitworm and cherry fruitworm have been caught. Spotted wing drosophila and blueberry maggot have been caught in a high-pressure unmanaged site.  

Want more blueberry specific content? Subscribe to Blueberry Bites! 

Strawberry harvest is wrapping up in Berrien and Van Buren counties. Once harvest is over it will be time to renovate perennial strawberry beds.  

Upcoming meetings 

Our weekly Monday Night South Michigan Fruit IPM Meetings will are a hybrid format. The meetings will be held in-person at the Southwest Michigan Research and Extension Center, 1791 Hillandale Rd, Benton Harbor, MI 49022, with virtual attendance available online. Our next meeting is Monday, June 17, at 5:30 p.m. No advanced signup is needed for attending in-person. The meetings are free, and one pesticide applicator credit is available for each meeting.    

The MSU Controlled Atmosphere (CA) Clinic on July 17 in Muskegon, Michigan, is organized by the MSU Department of Horticulture every other year to pass on new information relating to CA storage and warehousing of apple and other temperate fruit. This will be of primary interest to apple growers and storage operators.   

The meeting this year features four internationally recognized leaders in apple postharvest science: Christopher Watkins (New York), Jennifer DeEll (Ontario), Carolina Torres (Washington State University) and David Rudell (U.S. Department of Agriculture Agricultural Research Service – Wenatchee) and Randy Beaudry (MSU). Sign up here.  

The 2024 Michigan Viticulture Field Day is back for its 35th year. It will be held at the Southwest Michigan Research and Extension Center on July 31. Come for the education, stay for the steak dinner and local wine tasting. New this year, we are adding a second day for just the wine makers. The Michigan Enology Experience will be down the street from Southwest Michigan Research and Extension Center at the Lake Michigan College Welch Center the day after Viticulture Field Day on Aug. 1. We will talk wine production and tour some local wineries and see how they manage some of the challenges of winemaking in Michigan. Registration is available online. More information can be found in the article, "The 35th annual Michigan Viticulture Field Day and inaugural Michigan Enology Experience are approaching." 


This work is supported by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] 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.     

Did you find this article useful?