Southeast Michigan fruit update – June 18, 2024

Cherry harvest is starting as strawberry harvest ends. Be prepared for heat and spotted wing drosophila.

Bunches of tart cherries.
Tart cherries ready to harvest at Spicer’s in Fenton, Michigan, June 17, 2024. Photo by Derek Plotkowski, MSU Extension.

Welcome to the ninth in-season fruit article update for Southeast Michigan for the 2024 season. Throughout the season these updates will include information about the weather in the past week and the upcoming week, a fruit-by-fruit guide to current conditions with appropriate pest and disease updates, and other relevant observations. 

General observations 

In the two weeks since the last update, strawberry harvest has come and gone. Many U-picks have started offering raspberries and both sweet and tart cherries are starting soon. Peaches, pear and apples can still be hand thinned. Blueberries and grapes continue to expand, with the earliest blueberry varieties in harvest. In blueberries we are seeing fruit coloration, but we’re not quite at harvest yet. Fruit set has been good on grapes. 

We’ve seen an average of 1.1 inch of rain in the region over about 13 hours of rainfall for the last two weeks, while continued warm temperatures and humidity have brought conditions favorable for disease. When using Enviroweather and other weather models, keep in mind that the weather station closest to you may have different topography or be in the path of weather events that pass by your location. The growing degree-day (GDD) gap is widening and we are even further ahead of previous years on growing degree day accumulation.  

There is a daily chance this week of scattered storms and showers. With these events come increased risk for fungal infections like secondary apple scab and powdery mildew. You can see an overview of disease risks on the RimPro interactive location chart. Make sure to check the models frequently as they change with weather forecasts. These weather conditions may make finding a suitable spray date tricky. 

Local scouts in southeast Michigan have caught both apple maggot and spotted wing drosophila in the region. They continue to report catches of codling moth males in the region, with numbers remaining high. Obliquebanded leafroller populations have also been observed above threshold at some orchards. The trap line report at the Trevor Nichols Research Center in Fennville, Michigan, has caught its first cherry fruit fly for the season, but we haven’t seen it in southeast Michigan yet. Scab and fire blight pressure remain low and powdery mildew seems to have been kept under control, but the risk of powdery mildew in tree fruit and grapes remains high. 

Next week Monday, June 24 is our last Southern Michigan virtual grower meeting. You can attend by registering on our event page. It is a good opportunity to ask questions and receive RUP credits. See the latest weekly fruit meetings for southern Michigan on MSU’s Kaltura Media Space (these may take a few days to upload after the Monday meetings). 

Fruit-by-fruit conditions 


Apples in the region are generally in the 45–55 millimeter (mm) range. June drop has occurred in some orchards and hand-thinning can still be done. RimPro indicates that primary scab season is over with all spores being released, but secondary scab risk continues in places that have existing scab infections. Scab and fire blight strikes have been seen in Monroe County and other fire blight strikes have been seen blocks with historic pressure. 

Apples getting some size and color in Romeo, Michigan, June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Fruit is sizing up and starting to show some color in blueberry plantings in Fenton. We are past the primary season for mummy berry and it’s time to pay attention to fruit rots—Anthracnose and Alternaria. Spotted wing drosophila has been caught in the region. See Michigan State University Extension’s collection of factsheets and videos on spotted wing Drosophila. 

Blueberry fruitlets up to 11 mm in Fenton, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Summer red raspberry U-picks have opened and blackberries are sizing up alongside some continued bloom. Spotted wing drosophila has been caught in the region. See Michigan State University Extension’s collection of factsheets and videos on spotted wing Drosophila. 

Red raspberries ready for picking in Romeo, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Some U-picks in the region are starting tart cherries and sweet cherry harvest will be starting soon. Read this article on bird management options for fruit growers. Spotted wing drosophila has been caught in the region. See Michigan State University Extension’s collection of factsheets and videos on spotted wing Drosophila. 

Sweet cherry nearly ready to pick in South Lyon, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Fruit set in Concords, table grapes and cold hardy wine grapes has been good. Diseases of concern include powdery mildew, black rot and Phomopsis. On the insect side, tumid gallmaker is active this time of year. 

‘Frontenac’ grape fruit set at Youngblood Vineyard in Ray Township, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Harvest is wrapping up. Renovation should begin as soon as you are done harvesting. This is an important step to ensure continued productivity next season. Read this 2023 article on strawberry renovation for additional information. 

Strawberries harvested from a field in Romeo, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 

Peaches and nectarines 

Peaches in Fenton and Romeo are in the stage where expansion levels off and the pit starts to harden. The next chance to control brown rot will begin three weeks prior to harvest.  

Peach and pit sliced open in Romeo, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


Pears observed in Fenton were at 40 mm. 

Pear fruit development in Fenton, Michigan, on June 17, 2024. Photo by Derek Plotkowski, MSU Extension. 


European plums observed in Romeo are 30 mm in length. The critical period for most fungal control is from petal fall to late June, but for brown rot specifically the critical times are during bloom and later on at fruit coloring. 

Plum fruit in Romeo, Michigan, June 17, 2023. Photo by Derek Plotkowski, MSU Extension. 

Insect conditions 

In tree fruit, our insect concerns include codling moth, spotted wing drosophila (for cherries) and apple maggot. In small fruit, grape berry moth and spotted wing drosophila are the biggest concerns. More in-depth information can be found by watching the latest weekly fruit meetings for southern Michigan on MSU’s Kaltura Media Space (these may take a few days to upload after the Monday meetings). 

Aphids: Scouts have seen light infestations of green apple aphids in recent weeks. While some aphids are best controlled during dormancy, woolly apple aphids are controlled during the season. Aphids can stunt shoot growth and pave the way for secondary fungal infections like sooty mold. 

Borer complex: With catches of dogwood borer and lesser peachtree borer in Fennville, it is time to review management options for borers. You can read about the current status of Lorsban in this 2024 update. See the 2024 Fruit Management Guide and the article “Timing trunk sprays for the borer complex in cherries.” While chlorpyrifos is available for use this season, alternatives materials may be used to manage borers as well. Assail is a recommended material for a trunk spray once adult borers are active. 

Cherry fruitworm: Scouts in the state have caught cherry fruitworm. 

Codling moth: Codling moth catches are up, with scouts in southeast Michigan indicating counts are high even after sprays. We are roughly at 600 GDD50 after biofix, which puts us in the period where additional larvicides can be applied if needed. You can track the codling moth model on Enviroweather. 

Cranberry fruitworm: Scouts in the state have caught cranberry fruitworm. 

Grape berry moth: Grape berry moth has been caught, but control is usually most effective in the second and third generations. See this early season grape berry moth management article for more information. 

Oriental fruit moth: We will likely get the second generation of oriental fruit moth adults emerging in the next week (I reported this a couple weeks ago, but it does not seem to have happened yet). If control for the first generation wasn’t effective, sprays may be needed to control egglaying and larvae in the subsequent generation. 

Pear psylla: This may need control throughout the season. 

Potato leafhopper: Populations can build quickly in June and peak in July. These can cause leaf margins to brown and are a bigger issue in young plantings. 

Raspberry sawfly: Adults emerge in the spring and lay eggs on leaves before bloom. Larvae feed on the leaves. 

San Jose scale: Crawler stage has been reported as continuing by scouts in southeast Michigan. At this control point, crawlers can be targeted with larvicidal sprays, but this will likely not be effective for much longer. See the 2024 Fruit Management Guide. 

We have moved past the control periods for rosy apple aphid, mites, green fruitworm, oriental fruit moth, tarnished plant bug, plum curculio and black stem borer. 

Disease conditions 

Apple scab: We are at the end of primary scab season and models are not predicting secondary infection risk in the next week. Scab pressure seems light this year. 

Black knot: There is still time to prune out and burn black knot in plums and sour cherries. Fungicides may be used for limited control to supplement pruning and sanitation efforts. 

Brown rot: This disease affects stone fruit and can proliferate during bloom. The next chance to control is about three weeks before harvest when fruits start to color. 

Cherry leaf spot: We expect risk of infection on June 22. See this 2013 article on cherry leaf spot management. 

Fire blight: Some fire blight strikes have been reported in orchards that have had fire blight in past years, but there do not appear to be many new infections this year. Read this 2020 article from George Sundin for fire blight management options. 

Grape black rot: There is potential conidi infection on June 22 in the region. See this 2014 article for grape black rot management options and consult the 2024 Fruit Management Guide... 

Orange rust: With our advanced growing degree days this year, we are hit the risk period for orange rust in brambles early. Read the linked article for control options. 

Peach leaf curl: Symptoms are starting to appear. Control needed to be done before bud break. The next chance to control it will be with fall sprays. 

Phomopsis: In blueberries, the Phomopsis fungus is active from bud swell until after harvest. 

Powdery mildew of apple and pear: You can start to include products labeled for powdery mildew in sprays starting at tight cluster. We are in a high-risk period for infection, especially June 21, 22 and 27. 

Powdery mildew and downy mildew of grape: Scouting should start early for these diseases. There is risk of powdery and downy mildew infections on June 19–20 and 25–26 in the region. Read the linked article for control options. 

While not a disease, nutrient deficiencies can leave plants more susceptible to disease. Now that the plants have leafed out, you can start to see some symptoms. They can be hard to definitively diagnose without nutrient testing, but this article from Eric Hanson is a handy guide to what nutrient deficiency symptoms look like.  

Seasonal weather update 

In the last two weeks, southeast Michigan has seen on average of over 13 hours of rain accumulating to 1.1 inch of precipitation. We are ahead of the five-year average in both time and amount of rainfall. 

Liquid Precipitation Accumulation Jan. 1 - June 17, 2024, issued June 17, 2024
Station (County) Rainfall Total (in.) Current Hours with Rainfall Current Rainfall Total Average (5 Yr.) Hours with Rainfall  Average (5 Yr.)
Commerce (Oakland) 14.0 275 12.0 252
Deerfield (Monroe) 15.8 307 12.9 264
East Lansing MSU Hort (Ingham) 12.9 256 11.6 248
Emmett (St. Clair) 12.4 283 11.3 278
Flint (Genesee) 13.2 286 11.9 258
Freeland (Saginaw) 10.6 224 . .
Hudson (Lenawee) 16.0 295 12.3 265
Ithaca (Gratiot) 11.9 310 11.5 227
Lapeer (Lapeer) 13.8 328 9.8 241
Linwood (Bay) 12.0 245 11.5 231
Pigeon (Huron) . . . .
Richville/Frankenmuth (Tuscola) 13.3 264 10.4 223
Sandusky (Sanilac) 10.6 318 10.5 224
Romeo (Macomb) 13.9 272 11.1 236
Average of stations in this region: 13.1 281.8 11.4 245.6


Difference in Liquid Precipitation Accumulation from Jan. 1 observed June 4 and June 17, 2024; issued June 17, 2024
  Rainfall Total (in.)  Rainfall Total (in.)    Hours with Rainfall  Hours with Rainfall   
Station (County) 4-Jun 17-Jun Difference 4-Jun 17-Jun Difference
Commerce (Oakland) 12.3 14.0 1.6 261 275 14.0
Deerfield (Monroe) 14.9 15.8 0.9 297 307 10.0
East Lansing MSU Hort (Ingham) 10.9 12.9 1.9 240 256 16.0
Emmett (St. Clair) 11.4 12.4 1.0 269 283 14.0
Flint (Genesee) 12.2 13.2 1.1 272 286 14.0
Freeland (Saginaw) 10.0 10.6 0.6 210 224 14.0
Hudson (Lenawee) 14.8 16.0 1.2 284 295 11.0
Ithaca (Gratiot) 11.6 11.9 0.3 301 310 9.0
Lapeer (Lapeer) 12.5 13.8 1.3 312 328 16.0
Linwood (Bay) 10.8 12.0 1.2 235 245 10.0
Pigeon (Huron) . . . . . .
Richville/Frankenmuth (Tuscola) 12.4 13.3 1.0 251 264 13.0
Sandusky (Sanilac) 9.7 10.6 0.9 . . .
Romeo (Macomb) 12.8 13.9 1.2 255 272 17.0
Average of stations in this region: 12.0 13.1 1.1 265.6 278.8 13.2

In the short term, we are expecting variable conditions with scattered showers and thunderstorms possible every day. The early part of the week will be hot and humid, but early next week will bring dryer and cooler conditions. High temperatures this week will reach the mid-90s in the early part of the week with highs declining to the low 80s early next week. 

Laurel Harduar Morano with MSU’s College of Human Medicine says, “With a hot Michigan summer upon us, it is important to be mindful that hot weather can be dangerous while working outside. The heat produced by your body while working plus high outdoor temperatures makes it more likely for your body to overheat. To prevent overheating, do the following: drink plenty of fluids; take frequent breaks in the shade, and if possible, reschedule high energy tasks for earlier or later in the day.  

“Call 911 immediately if severe symptoms of overheating occur such as confusion, slurred speech, fainting, nausea/vomiting, rapid pulse, seizures, hot dry skin, or heavy sweating. Then, move the person to a cool place and help lower their temperature with a cool wet cloth and/or cool bath. Do not leave the person alone. Death can occur if the body does not cool down, so it is essential to have a plan before such symptoms occur.” 

In the medium term, we are looking at above-normal temperatures and near to above-normal precipitation through the next week. The long lead outlooks are still calling for warmer than normal conditions for the late spring and summer seasons with normal precipitation levels. 

Our regional average growing degree day accumulation for the season are ahead of the five-year average by 287 GDD at 42 F, 243 GDD at 45 F and 168 GDD at 50 F (see table below). This puts us at one to two weeks ahead of normal in most of the region. Read this Michigan State University Extension article to learn more about degree days: Understanding growing degree-days. 

Degree Day Accumulation Jan. 1 -June 17, 2024, Forecast from June 18-June 24, 2024; issued June 17, 2024
Station (County) Degree Days Base 42°F Current Degree Days Base 42°F  Average (5 Yr.) Degree Days Base 42°F Forecast Degree Days Base 45°F Current Degree Days Base 45°F Average (5 Yr.) Degree Days Base 45°F Forecast Degree Days Base 50°F Current Degree Days Base 50°F Average (5 Yr.) Degree Days Base 50°F Forecast
Commerce (Oakland) 1416 1134 1656 1171 932 1393 816 650 1008
Deerfield (Monroe) 1624 1282 1868 1357 1059 1583 968 749 1165
East Lansing MSU Hort (Ingham) 1522 1187 1761 1268 980 1489 894 691 1085
Emmett (St. Clair) 1303 1050 1532 1065 856 1275 721 588 901
Flint (Genesee) 1531 1231 1770 1278 1020 1499 905 721 1095
Freeland (Saginaw) 1384 1106 1613 1146 912 1357 802 639 983
Hudson (Lenawee) 1529 1188 1771 1276 981 1500 907 691 1101
Ithaca (Gratiot) 1503 1176 1739 1257 977 1474 893 693 1081
Lapeer (Lapeer) 1418 1133 1647 1174 931 1385 818 652 999
Linwood (Bay) 1260 1030 1484 1033 842 1239 706 582 881
Pigeon (Huron) 1257 1011 1464 1026 828 1215 701 573 860
Richville/Frankenmuth (Tuscola) 1443 1173 1673 1199 972 1411 839 688 1020
Sandusky (Sanilac) 1312 1045 1534 1076 857 1280 741 594 915
Romeo (Macomb) 1420 1153 1659 1172 947 1393 813 659 1004
Average of stations in this region: 1423 1136 1655 1178 935 1392 823 655 1007


Difference in Degree Day Accumulation from Jan. 1 observed June 4 and June 17, 2024; issued June 17, 2024
Station (County) Degree Days Base 42°F   Degree Days Base 42°F   Degree Days Base 42°F  Degree Days Base 45°F Degree Days Base 45°F Degree Days Base 45°F  Degree Days Base 50°F  Degree Days Base 50°F Degree Days Base 50°F 
  4-Jun 17-Jun Difference 4-Jun 17-Jun Difference 4-Jun 17-Jun Difference
Commerce (Oakland) 1100 1416 316.0 894 1171 277.0 602 816 214.0
Deerfield (Monroe) 1275 1624 349.0 1047 1357 310.0 722 968 246.0
East Lansing MSU Hort (Ingham) 1195 1522 327.0 980 1268 288.0 669 894 225.0
Emmett (St. Clair) 1005 1303 298.0 805 1065 260.0 523 721 198.0
Flint (Genesee) 1196 1531 335.0 983 1278 295.0 673 905 232.0
Freeland (Saginaw) 1060 1384 324.0 861 1146 285.0 580 802 222.0
Hudson (Lenawee) 1183 1529 346.0 969 1276 307.0 664 907 243.0
Ithaca (Gratiot) 1154 1503 349.0 947 1257 310.0 648 893 245.0
Lapeer (Lapeer) 1106 1418 312.0 901 1174 273.0 608 818 210.0
Linwood (Bay) 950 1260 310.0 762 1033 271.0 497 706 209.0
Pigeon (Huron) 938 1257 319.0 746 1026 280.0 485 701 216.0
Richville/Frankenmuth (Tuscola) 1114 1443 329.0 909 1199 290.0 613 839 226.0
Sandusky (Sanilac) 995 1312 317.0 798 1076 278.0 527 741 214.0
Romeo (Macomb) 1100 1420 320.0 891 1172 281.0 595 813 218.0
Average of stations in this region: 1098 1423 325 892 1178 286 600 823 223


Watch Jeff Andresen's biweekly agricultural weather forecast reports.  

More information and reports on normal weather conditions and departures from normal can be found on the NOAA Climate Prediction Center website, NOAA U.S. Climate Normals website, NOAA Climate Normals Quick Access Page (which may be searched by region), and Midwest Regional Climate Center website. 


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