Southeast Michigan fruit update – September 4, 2024
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EmailApple harvest moves into Honeycrisp. Cold-hardy wine grapes are at peak harvest.
Welcome to the 16th 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
Apple maturity reports for the season from around the state have started. You can find these reports on the Michigan State University Extension Apple Maturity page. Southeast Michigan apple maturity is covered in this report and in the statewide apple report, which will be published after the other reports.
In the two weeks since the last update, many farms have opened their cider mills and apple u-picks for the season. Seedless and wine grape harvests are also in their peak period.
We’ve seen an average of 0.8 inches of rain in the region over about 6.6 hours of rainfall in the last two weeks while we’ve experienced warmer than normal temperatures. When using Michigan State University (MSU) 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 legacy version of Enviroweather is currently unavailable, so for the time being it is necessary to use the newer version of the site. A virtual training was offered on using Enviroweather on Friday, June 26, and the recording can be found here.
We are expecting a front of rain to come through later this week ushering in cool fall-like conditions into the weekend. You can see you an overview of disease risks on the RimPro interactive location chart. Make sure to check the models frequently as they change with weather forecasts.
Many of our major pest populations are on the decline, including codling moth, oriental fruit moth and apple maggot. Brown marmorated stink bug counts are climbing in orchards. Brown marmorated stink bug can be challenging to control because of their activity close to harvest. See this fact sheet on managing brown marmorated stink bug. Spotted wing drosophila pressure is very high this year across the state in blueberries and brambles. Low trap counts do not necessarily correlate with low presence in fruit. Secondary scab pressure remains low and powdery mildew seems to have been kept under control, but the risk of powdery mildew in tree fruit and grapes remains high for the entire week. Bitter pit incidence, especially in ‘Honeycrisp’ apples has been very high this year.
Fruit-by-fruit conditions
Apples
Growers in warmer parts of the region (Lenawee and Monroe counties) have harvested ‘RubyMac’ and done first picks of ‘Honeycrisp.’ Non-retained ‘Gala’ in warmers parts were harvested last week while retained fruit will be picked later this week. You can see our predicted harvest dates for southeast Michigan. We expect high infection probability for powdery mildew the entirety of the next week.
Blueberries
Blueberry harvest has largely wrapped up, with a few u-picks open to pick the last berries.
Brambles
Many raspberry u-picks are open for their fall bearing fruit. Spotted wing drosophila (SWD) has been caught in the region. See our MSU Extension collection of factsheets and videos on SWD.
Grapes
The statewide grape report is published weekly on the MSU Extension Grapes website. Seedless grape harvest continues, with ‘Marquis’ harvest wrapping up in Britton and ‘Mars’ on the horizon. Cold-hardy wine grape continues, with growers moving through ‘Itasca,’ ‘Petite Pearl’ and ‘Prairie Star.’ ‘Concord’ harvest in Britton could start by the end of the week, while further north in Romeo growers are still picking ‘Fredonia’ and waiting on ‘Niagara.’ RimPro models for Romeo through Sept. 13 indicate very low risk of black rot conidia infection. Downy mildew risk will be high on Sept. 6-7. Powdery mildew will have moderate to severe risk for the entire week.
Pears
‘Bartlett’ pear harvest has wrapped up in Fenton. Bosc pears harvest has not yet started. Some sooty blotch has been seen, which is a problem exacerbated by pear psylla.
Plums
Italian plums in Romeo have been harvested with ‘Stanley’ plums expected in the next week or so. Like other crops their harvest is likely to be ahead of schedule.
Insect conditions
Our late summer insect conditions remain relatively consistent from week to week and the last few weeks have been pretty quiet. In tree fruit, our primary insect concern is brown marmorated stink bug. In small fruit, spotted wing drosophila and grape berry moth are the biggest concerns.
Aphids: Some light infestations of green apple aphids continue to be reported by scouts. Woolly apple aphid counts are down after a mid-summer spike. While some aphids are best controlled during dormancy, woolly apple aphids are controlled during the season. Woolly apple aphids have moved towards terminals, which is a transition that happens in mid-summer. Aphids can stunt shoot growth and pave the way for secondary fungal infections like sooty mold.
Brown marmorated stink bug: Scouts are reporting increasing adults, especially in orchards that have historically had problems. See this factsheet on managing brown marmorated stink bug in Michigan orchards.
Borer complex: Lesser peachtree borer numbers are declining after a brief increase in Fennville and greater peachtree borer and dogwood borer counts are down to zero. You can read about the current status of Lorsban in this 2024 update. 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.
Codling moth: Codling moth catches have increased in Fennville but remain low in southeast Michigan. You can track the codling moth model on Enviroweather.
Grape berry moth: Grape berry moth catch is low in Fennville, with no problem reports in southeast Michigan. Control is usually most effective in the second and third generations.
Japanese beetle: These are generalist feeders with a single generation per season. They have been seen in apple orchards in the region but we seem to be past the peak. If needed insecticides can be used to control populations.
Oriental fruit moth: Counts remain low in Fennville and haven’t been caught recently southeast Michigan. If control for the first generation wasn’t effective, sprays may be needed to control egg laying and larvae in the subsequent generation.
Pear psylla: This may need control throughout the season.
San Jose scale: Characteristic spots on fruit are starting to appear in some locations. Male San Jose scale counts have dropped over the last couple weeks in Fennville. See the fruit guide. Some growers have asked about mating disruption in San Jose scale. Research indicates that it is an effective tool but there are no commercially available approved products. This survey is gauging interest in this method of control.
Spotted wing drosophila are still be caught in traps and larvae are still being found in fruit. Trap counts don’t necessarily correlate with crop pressure- high pressure can exist with low trap counts.
Disease conditions
Apple scab: This week has a low probability of secondary scab infection. Scab pressure has been light this year.
Brown rot: This disease affects stone fruit and can proliferate during bloom. There may still be time to control in later varieties starting 3 weeks before harvest when fruits start to color, but be mindful of pre-harvest intervals.
Cherry leaf spot: We do not expect the risk of infection in the next week except for a slight risk on September 6. See this 2013 article on cherry leaf spot management. It can be helpful to control cherry leaf spot outside of the season to prevent inoculum buildup in the orchard.
Fire blight: We do not anticipate fire blight risk this week. Strikes have primarily been reported in orchards that have had fire blight in past years, but there do not appear to be many new infections this year. Fire blight is not limited to springtime infection and it can infect orchards with existing infections in the fall. Read this 2020 article from George Sundin for fire blight management options.
Fruit rots: Rots like bitter rot and black rot can be controlled as early as first cover in apples. Our recent wet weather tends to favor rot development.
Grape black rot: There is not much infection risk this week. See this 2014 article for grape black rot management options and consult E-154.
Orange rust: Orange rust continues to be a potential problem in brambles.
Peach leaf curl: Control needed to be done before bud break. The next chance to control it will be with fall sprays in preparation for next season.
Phomopsis: In blueberries the Phomopsis fungus is active from bud swell until after harvest. Phomopsis has been seen in grapes in the region.
Powdery mildew of apple and pear: You can start to include products labeled for powdery mildew in sprays starting at tight cluster. There is a high risk of infection the entire week.
Powdery mildew and downy mildew of grape: Scouting should start early for these diseases. Powdery mildew will have moderate to severe risk for the entire week. Downy mildew risk will be high on Sept. 6-7.
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, we saw about 6.6 hours of rain accumulating to 0.8 inches of precipitation. We are ahead of the five-year average in both time and amount of rainfall.
| Liquid Precipitation Accumulation Jan. 1 - September 4, 2024, issued September 4, 2024 | ||||
|---|---|---|---|---|
| Station (County) | Rainfall Total (in.) Current | Hours with Rainfall Current | Rainfall Total Average (5 Yr.) | Hours with Rainfall Average (5 Yr.) |
| Commerce (Oakland) | 26.8 | 370 | 22.6 | 350 |
| Deerfield (Monroe) | 23.8 | 389 | 21.0 | 352 |
| East Lansing MSU Hort (Ingham) | 23.4 | 369 | 20.9 | 337 |
| Emmett (St. Clair) | 20.3 | 388 | 19.3 | 372 |
| Flint (Genesee) | 26.1 | 400 | 22.5 | 352 |
| Freeland (Saginaw) | 18.1 | 305 | 16.0 | 299 |
| Hudson (Lenawee) | 21.9 | 371 | 21.1 | 360 |
| Ithaca (Gratiot) | 19.2 | 417 | 19.9 | 334 |
| Lapeer (Lapeer) | 23.7 | 502 | 19.3 | 357 |
| Linwood (Bay) | 20.9 | 344 | 19.9 | 320 |
| Pigeon (Huron) | . | . | . | . |
| Richville/Frankenmuth (Tuscola) | 23.8 | 362 | 19.3 | 311 |
| Romeo (Macomb) | 26.9 | 384 | 22.0 | 332 |
| Sandusky (Sanilac) | 18.2 | 487 | 17.2 | 361 |
| Average of stations in this region: | 22.5 | 391.4 | 20.1 | 341.3 |
| Difference in Liquid Precipitation Accumulation from Jan. 1 observed August 20 and September 4, 2024; issued September 4, 2024 | ||||||
|---|---|---|---|---|---|---|
| Rainfall Total (in.) | Rainfall Total (in.) | Hours with Rainfall | Hours with Rainfall | |||
| Station (County) | 20-Aug | 4-Sep | Difference | 20-Aug | 4-Sep | Difference |
| Commerce (Oakland) | 26.0 | 26.8 | 0.8 | 360 | 370 | 10.0 |
| Deerfield (Monroe) | 21.9 | 23.8 | 1.8 | 382 | 389 | 7.0 |
| East Lansing MSU Hort (Ingham) | 22.0 | 23.4 | 1.4 | 361 | 369 | 8.0 |
| Emmett (St. Clair) | 19.7 | 20.3 | 0.6 | 380 | 388 | 8.0 |
| Flint (Genesee) | 25.0 | 26.1 | 1.1 | 396 | 400 | 4.0 |
| Freeland (Saginaw) | 17.5 | 18.1 | 0.6 | 300 | 305 | 5.0 |
| Hudson (Lenawee) | 21.5 | 21.9 | 0.4 | 367 | 371 | 4.0 |
| Ithaca (Gratiot) | 19.0 | 19.2 | 0.2 | 413 | 417 | 4.0 |
| Lapeer (Lapeer) | 22.7 | 23.7 | 1.0 | 495 | 502 | 7.0 |
| Linwood (Bay) | 20.4 | 20.9 | 0.5 | 338 | 344 | 6.0 |
| Pigeon (Huron) | . | . | . | . | . | . |
| Richville/Frankenmuth (Tuscola) | 23.0 | 23.8 | 0.8 | 356 | 362 | 6.0 |
| Romeo (Macomb) | 26.2 | 26.9 | 0.8 | 373 | 384 | 11.0 |
| Sandusky (Sanilac) | 17.9 | 18.2 | 0.3 | 481 | 487 | 6.0 |
| Average of stations in this region: | 21.7 | 22.5 | 0.8 | 384.8 | 391.4 | 6.6 |
In the short term, we are expecting sunny and dry weather through Thursday. Storms overnight Thursday will bring in colder and cloudier conditions for the weekend. Temperatures through Thursday will be in the mid-80s, but over the weekend highs will be in the 50s and 60s with lows in the 40s.
The medium term outlooks are projecting a transition to warmer than normal conditions with below normal precipitation after the cool temperatures of the next few days. The long lead currently calls for warmer than normal conditions with normal precipitation.
Our regional average growing degree day accumulation for the season are ahead of the five-year averages. 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 -September 4, 2024, Forecast from September 5-10, 2024; issued September 4, 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) | 3646 | 3437 | 3789 | 3163 | 3018 | 3285 | 2420 | 2329 | 2509 |
| Deerfield (Monroe) | 3982 | 3756 | 4131 | 3478 | 3286 | 3607 | 2703 | 2564 | 2799 |
| East Lansing MSU Hort (Ingham) | 3706 | 3508 | 3843 | 3213 | 3054 | 3330 | 2456 | 2359 | 2540 |
| Emmett (St. Clair) | 3359 | 3285 | 3494 | 2886 | 2842 | 3001 | 2165 | 2165 | 2246 |
| Flint (Genesee) | 3823 | 3649 | 3965 | 3332 | 3191 | 3453 | 2571 | 2487 | 2659 |
| Freeland (Saginaw) | 3600 | 3456 | 3738 | 3123 | 3012 | 3240 | 2390 | 2331 | 2475 |
| Hudson (Lenawee) | 3850 | 3582 | 4001 | 3362 | 3128 | 3493 | 2613 | 2432 | 2710 |
| Ithaca (Gratiot) | 3834 | 3601 | 3970 | 3345 | 3151 | 3461 | 2585 | 2455 | 2669 |
| Lapeer (Lapeer) | 3615 | 3425 | 3749 | 3134 | 2976 | 3134 | 2398 | 2292 | 2480 |
| Linwood (Bay) | 3375 | 3243 | 3506 | 2912 | 2811 | 3023 | 2202 | 2148 | 2281 |
| Pigeon (Huron) | 3463 | 3301 | 3601 | 2994 | 2868 | 3111 | 2280 | 2205 | 2363 |
| Richville/Frankenmuth (Tuscola) | 3673 | 3528 | 3807 | 3190 | 3079 | 3303 | 2438 | 2384 | 2520 |
| Romeo (Macomb) | 3686 | 3506 | 3829 | 3201 | 3056 | 3323 | 2455 | 2361 | 2540 |
| Sandusky (Sanilac) | 3539 | 3345 | 3666 | 3063 | 2908 | 3170 | 2338 | 2237 | 2413 |
| Average of stations in this region: | 3654 | 3473 | 3792 | 3171 | 3027 | 3281 | 2430 | 2339 | 2515 |
| Difference in Degree Day Accumulation from Jan. 1 observed August 20 and September 4, 2024; issued September 4, 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-Aug | 4-Sep | Difference | 20-Aug | 4-Sep | Difference | 20-Aug | 4-Sep | Difference | |
| Commerce (Oakland) | 3251 | 3646 | 395.0 | 2812 | 3163 | 351.0 | 2142 | 2420 | 278.0 |
| Deerfield (Monroe) | 3569 | 3982 | 413.0 | 3109 | 3478 | 369.0 | 2404 | 2703 | 299.0 |
| East Lansing MSU Hort (Ingham) | 3315 | 3706 | 391.0 | 2868 | 3213 | 345.0 | 2181 | 2456 | 275.0 |
| Emmett (St. Clair) | 3003 | 3359 | 356.0 | 2574 | 2886 | 312.0 | 1923 | 2165 | 242.0 |
| Flint (Genesee) | 3415 | 3823 | 408.0 | 2969 | 3332 | 363.0 | 2282 | 2571 | 289.0 |
| Freeland (Saginaw) | 3221 | 3600 | 379.0 | 2788 | 3123 | 335.0 | 2125 | 2390 | 265.0 |
| Hudson (Lenawee) | 3446 | 3850 | 404.0 | 3002 | 3362 | 360.0 | 2321 | 2613 | 292.0 |
| Ithaca (Gratiot) | 3430 | 3834 | 404.0 | 2986 | 3345 | 359.0 | 2298 | 2585 | 287.0 |
| Lapeer (Lapeer) | 3229 | 3615 | 386.0 | 2792 | 3134 | 342.0 | 2126 | 2398 | 272.0 |
| Linwood (Bay) | 3011 | 3375 | 364.0 | 2593 | 2912 | 319.0 | 1952 | 2202 | 250.0 |
| Pigeon (Huron) | 3084 | 3463 | 379.0 | 2660 | 2994 | 334.0 | 2018 | 2280 | 262.0 |
| Richville/Frankenmuth (Tuscola) | 3285 | 3673 | 388.0 | 2847 | 3190 | 343.0 | 2169 | 2438 | 269.0 |
| Romeo (Macomb) | 3287 | 3686 | 399.0 | 2846 | 3201 | 355.0 | 2174 | 2455 | 281.0 |
| Sandusky (Sanilac) | 3162 | 3539 | 377.0 | 2732 | 3063 | 331.0 | 2078 | 2338 | 260.0 |
| Average of stations in this region: | 3265 | 3654 | 389 | 2827 | 3171 | 344 | 2157 | 2430 | 273 |
| Difference in Liquid Precipitation Accumulation from Jan. 1 observed August 20 and September 4, 2024; issued September 4, 2024 | ||||||
|---|---|---|---|---|---|---|
| Rainfall Total (in.) | Rainfall Total (in.) | Hours with Rainfall | Hours with Rainfall | |||
| Station (County) | 20-Aug | 4-Sep | Difference | 20-Aug | 4-Sep | Difference |
| Commerce (Oakland) | 26.0 | 26.8 | 0.8 | 360 | 370 | 10.0 |
| Deerfield (Monroe) | 21.9 | 23.8 | 1.8 | 382 | 389 | 7.0 |
| East Lansing MSU Hort (Ingham) | 22.0 | 23.4 | 1.4 | 361 | 369 | 8.0 |
| Emmett (St. Clair) | 19.7 | 20.3 | 0.6 | 380 | 388 | 8.0 |
| Flint (Genesee) | 25.0 | 26.1 | 1.1 | 396 | 400 | 4.0 |
| Freeland (Saginaw) | 17.5 | 18.1 | 0.6 | 300 | 305 | 5.0 |
| Hudson (Lenawee) | 21.5 | 21.9 | 0.4 | 367 | 371 | 4.0 |
| Ithaca (Gratiot) | 19.0 | 19.2 | 0.2 | 413 | 417 | 4.0 |
| Lapeer (Lapeer) | 22.7 | 23.7 | 1.0 | 495 | 502 | 7.0 |
| Linwood (Bay) | 20.4 | 20.9 | 0.5 | 338 | 344 | 6.0 |
| Pigeon (Huron) | . | . | . | . | . | . |
| Richville/Frankenmuth (Tuscola) | 23.0 | 23.8 | 0.8 | 356 | 362 | 6.0 |
| Romeo (Macomb) | 26.2 | 26.9 | 0.8 | 373 | 384 | 11.0 |
| Sandusky (Sanilac) | 17.9 | 18.2 | 0.3 | 481 | 487 | 6.0 |
| Average of stations in this region: | 21.7 | 22.5 | 0.8 | 384.8 | 391.4 | 6.6 |
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.
