Southeast Michigan fruit update – May 30, 2024

Strawberry harvests are starting in southeast Michigan.

Ripened strawberries on a bush.
Strawberries ripening at Westview Orchards in Romeo, Michigan, May 28, 2024. Photo by Derek Plotkowski, MSU Extension.

Welcome to the seventh 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

Many growers in the region are starting to pick strawberries, with many opening for U-pick this weekend. The crop is looking good this year.

The last week has largely seen increased precipitation along with above average temperatures, despite a few days with cooler temperatures. 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. Tree fruit fruitlets are expanding and many growers are still doing thinning applications while the threats of scan and fire blight wane. In brambles and blueberries, we are seeing fruit set with some continued bloom. Grapes are getting close to bloom and we have seen wild grape bloom in warmer parts of the state.

We are expecting scattered showers developing on Saturday, June 1, and lasting through the weekend into Monday. 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 continue to report catches of codling moth males in the region, with one scout commenting that the counts are very high. There hasn’t been much scab seen, but powdery mildew pressure is high this year. Fire blight has been seen in orchards where it has been a problem in the past. The trap line report at the Trevor Nichols Research Center in Fennville, Michigan,  also that insects in the cherry borer complex are continuing activity while leaf roller catches are down.

I encourage our growers to attend the weekly southern Michigan grower meetings virtually on Monday evenings 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 sizing up to 22-25 millimeters (mm) in Fenton and Romeo and as large as 30 mm in Britton. 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. Growers in cooler regions may still have time for sprays for chemical thinning. You can consult this 2022 article from Michigan State University Extension on apple thinning strategies.

Apples hanging from a tree.
‘Golden Delicious’ at 22 mm at the Blake’s in South Lyon, Michigan, May 28, 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 blights and phomopsis. Cranberry fruitworm counts are increasing at the Trevor Nichols trap line.

Blueberry fruitlets.
Blueberry fruitlets up to 11 mm in Fenton, Michigan, on May 28, 2024. Photo by Derek Plotkowski, MSU Extension.


We are seeing continued fruit set in summer red raspberries at sites in Fenton and Romeo while blackberries in warmers parts of the region are in full bloom and starting fruit set. I’ve gotten reports of orange rust in the region. Watch out for orange rust and raspberry sawfly.

Blackberries starting to bloom.
Fruit set and continued bloom in blackberries in Plymouth, Michigan, on May 30, 2024. Photo by Derek Plotkowski, MSU Extension.


We are seeing fruit expansion in both sweet and tart cherries in Fenton and Romeo with fruit at 15 mm in tart cherries and 18 mm in sweet cherries. Sweet cherries in warmer areas are starting to show color. There is a risk of cherry leaf spot infection on June 2, 5-6 and 8.

Sweet cherries growing on a tree.
Sweet cherry coloring in Britton, Michigan, on May 29, 2024. Photo by Derek Plotkowski, MSU Extension.


Inflorescences continue to develop in table and wine grapes. I have yet to see wild grape bloom, which is the biofix we use for control of grape berry moth, but it has been seen in other parts of the state.

Grapes growing.
‘Concord’ grape with inflorescence in Fenton, Michigan, on May 28, 2024. Photo by Derek Plotkowski, MSU Extension.


Harvest is starting. Be aware of preharvest intervals if you have to do any additional sprays.

Ripe strawberries on a bush.
Fruit ripening in field strawberries in Romeo, Michigan, on May 28, 2024. Photo by Derek Plotkowski, MSU Extension.

Peaches and nectarines

Peaches in Fenton and Romeo are growing quickly, with some as high as 29 mm in diameter. The next chance to control brown rot will begin three weeks prior to harvest.

A peach hanging from a tree.
Peach fruitlets in Fenton, Michigan, May 28, 2024. Photo by Derek Plotkowski, MSU Extension.


Pears observed in Fenton were at 24 mm.

Pears hanging from a tree.
Pear fruit development in Fenton, Michigan, May 28, 2024 Photo by Derek Plotkowski, MSU Extension.


European plums in Fenton are 18 mm in diameter. 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.

A plum hanging from a tree.
Plum fruit at 18 mm in Fenton, Michigan, May 20, 2023. Photo by Derek Plotkowski, MSU Extension.

Insect conditions

Much of this week’s information is the same as last week’s. With many fruits at petal fall we are moving into first cover, but if your crops are still blooming remember to prioritize pollinator protection. In tree fruit our insect concerns include codling moth and San Jose scale. In small fruit, grape berry moth, raspberry sawfly, cranberry fruit worm are of concern. 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: 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 American plum 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” for more information. 

Codling moth: Codling moth catches are up, with scouts indicating that it is a heavy year. We are roughly at 300 GDD50 after biofix, so there may be time for egg hatch larvicidal sprays in cooler areas (normally at 250 GDD50 after biofix) with delayed spray timing occurring around 350 GDD50 after biofix. 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.

Oriental fruit moth: Catches remain low. We are past the control points for oriental fruit moth.

Plum curculio: Plum curculio remains active around the region. In warm conditions like the ones we are experiencing, adults move from overwintering sites into orchards. Watch especially in areas near woods or hedgerows. Products that as oviposition deterrents and feeding killers can be used in apples and cherries at this point, while those that are just feeding killers are no longer recommended.

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

Redbanded leaf roller: Flight are decreasing.

Rose chafer: These emerge from soil in late May to early June. Treatment is only necessary with large populations.

San Jose scale: Crawler stage has been reported by scouts in southeast Michigan. At this control point, crawlers can be targeted with larvicidal sprays. See the 2024 Fruit Management Guide.

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

Disease conditions

Apple scab: We are at the end of primary scab season. RimPro is currently reporting a risk of secondary scab infection events on June 2, 5 and 6 in the region. Scab pressure seems light this year.

Apple scab on apple leaf.
Apple scab on leaves in Monroe County on May 29, 2024. Photo by Derek Plotkowski, MSU Extension.

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 moderate risk of infection on June 2, 5-6 and 8. 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. Monitor RimPro, Enviroweather and integrated pest management updates for spray timing. Read this 2020 article from George Sundin for fire blight management options.

Grape black rot: There is potential conidi infection on June 2, 5 and 6 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 hitting 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 2, 4 and 5.

Powdery mildew and downy mildew of grape: Scouting should start early for these diseases. There is risk of downy mildew infection on June 2, 5 and 6 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 week, southeast Michigan has seen on average of nearly 22 hours of rain accumulating to 1.3 inches of precipitation. We are ahead of the five-year average in both time and amount of rainfall.

Liquid Precipitation Accumulation Jan. 1 - May 30, 2024, issued May 30, 2024
Station (County) Rainfall Total (in.) Current Hours with Rainfall Current Rainfall Total Average (5 Yr.) Hours with Rainfall  Average (5 Yr.)
Commerce (Oakland) 12.1 254 10.2 229
Deerfield (Monroe) 14.5 291 11.5 244
East Lansing MSU Hort (Ingham) 10.9 236 9.9 228
Emmett (St. Clair) 11.3 261 9.7 254
Flint (Genesee) 12.0 266 9.8 235
Freeland (Saginaw) 9.8 205 . .
Hudson (Lenawee) 14.6 275 10.5 243
Ithaca (Gratiot) 11.4 295 9.7 204
Lapeer (Lapeer) 12.3 305 8.3 216
Linwood (Bay) 10.7 231 9.9 206
Pigeon (Huron) . . . .
Richville/Frankenmuth (Tuscola) 12.2 245 8.6 200
Sandusky (Sanilac) 9.5 259 8.7 198
Romeo (Macomb) 12.6 248 9.6 212
Average of stations in this region: 11.8 259.3 9.7 222.5
Difference in Liquid Precipitation Accumulation from Jan. 1 observed May 20 and May 30, 2024; issued May 30, 2024
  Rainfall Total (in.)  Rainfall Total (in.)    Hours with Rainfall  Hours with Rainfall   
Station (County) 20-May 30-May Difference 20-May 30-May Difference
Commerce (Oakland) 11.2 12.1 0.9 241 254 13.0
Deerfield (Monroe) 12.8 14.5 1.7 276 291 15.0
East Lansing MSU Hort (Ingham) 10.0 10.9 0.0 219 236 17.0
Emmett (St. Clair) 9.6 11.3 1.7 239 261 22.0
Flint (Genesee) 10.2 12.0 1.8 242 266 24.0
Freeland (Saginaw) 8.9 9.8 1.0 187 205 18.0
Hudson (Lenawee) 13.6 14.6 1.0 263 275 12.0
Ithaca (Gratiot) 9.9 11.4 1.5 276 295 19.0
Lapeer (Lapeer) 10.4 12.3 2.0 284 305 21.0
Linwood (Bay) 9.6 10.7 1.1 208 231 23.0
Pigeon (Huron) . . . . . .
Richville/Frankenmuth (Tuscola) 11.0 12.2 1.2 219 245 26.0
Sandusky (Sanilac) 8.7 9.5 0.9 198 259 61.0
Romeo (Macomb) 10.2 12.6 2.4 228 248 20.0
Average of stations in this region: 10.5 11.8 1.3 236.9 259.3 22.4

In the short term, we are expecting scattered showers developing on Saturday and lasting through the weekend into Monday. Temperatures will hit highs in the mid-80s next week with the weekly lows happening Friday, hitting the 40s.

In the medium-term, we are looking at above normal precipitation and temperatures into early June. 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 280 GDD at 42 F, 236 GDD at 45 F and 162 GDD at 50 F (see table below). This puts us 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 -May 30, 2024, Forecast from May 31-June 5, 2024; issued May 30, 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) 994 709 1151 803 561 941 535 366 644
Deerfield (Monroe) 1161 827 1320 948 658 1089 648 434 759
East Lansing MSU Hort (Ingham) 1083 752 1236 883 599 1018 596 395 703
Emmett (St. Clair) 911 656 1054 725 514 850 466 331 563
Flint (Genesee) 1083 785 1241 884 627 1024 599 416 709
Freeland (Saginaw) 946 679 1098 762 538 896 507 352 611
Hudson (Lenawee) 1072 753 1228 873 600 1011 592 396 700
Ithaca (Gratiot) 1029 725 1183 837 580 973 563 385 671
Lapeer (Lapeer) 1004 722 1152 813 573 944 544 378 645
Linwood (Bay) 844 617 992 671 483 801 431 310 532
Pigeon (Huron) 830 606 976 653 477 781 416 309 515
Richville/Frankenmuth (Tuscola) 998 733 1152 809 585 945 537 389 644
Sandusky (Sanilac) 889 637 1031 707 503 831 459 327 555
Romeo (Macomb) 998 718 1150 804 566 938 532 366 637
Average of stations in this region: 989 709 1140 798 562 932 530 368 635
Difference in Degree Day Accumulation from Jan. 1 observed May 20 and May 30, 2024; issued May 30, 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 
  20-May 30-May Difference 20-May 30-May Difference 20-May 30-May Difference
Commerce (Oakland) 773 994 221.0 611 803 192.0 390 535 145.0
Deerfield (Monroe) 914 1161 247.0 731 948 217.0 480 648 168.0
East Lansing MSU Hort (Ingham) 861 1083 222.0 690 883 193.0 451 596 145.0
Emmett (St. Clair) 704 911 207.0 547 725 178.0 335 466 131.0
Flint (Genesee) 856 1083 227.0 687 884 197.0 449 599 150.0
Freeland (Saginaw) 724 946 222.0 570 762 192.0 363 507 144.0
Hudson (Lenawee) 831 1072 241.0 662 873 211.0 430 592 162.0
Ithaca (Gratiot) 799 1029 230.0 637 837 200.0 412 563 151.0
Lapeer (Lapeer) 792 1004 212.0 630 813 183.0 407 544 137.0
Linwood (Bay) 642 844 202.0 498 671 173.0 306 431 125.0
Pigeon (Huron) 626 830 204.0 479 653 174.0 291 416 125.0
Richville/Frankenmuth (Tuscola) 776 998 222.0 616 809 193.0 393 537 144.0
Sandusky (Sanilac) 679 889 210.0 526 707 181.0 326 459 133.0
Romeo (Macomb) 773 998 225.0 608 804 196.0 384 532 148.0
Average of stations in this region: 768 989 221 607 798 191 387 530 143

A map of Michigan with areas highlighted showing the differences in heat accumulation.

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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