Southeast Michigan fruit update – June 6, 2023

Fruit set in tree fruit, small fruit bloom, dry weather.

Blueberry fruits.
Blueberry fruits starting to show color at Spicer’s Orchard in Fenton, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Welcome to the ninth in-season fruit article update for southeast Michigan for the 2023 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

The dry conditions from the last week have put the southern parts of our region into “abnormally dry” conditions according to the U.S. Drought Monitor. Michigan State University Extension has a collection of articles related to drought on its drought resources page. The dry and warm conditions will continue, though we have a chance for some showers over the weekend. Many of you have been irrigating your crops for some time and I expect that to continue for the foreseeable future. On the positive side, our entomology experts believe that the low moisture conditions will delay and reduce the incidence of spotted wing Drosophila.

The warm weather has pushed more of our crops along in their development. Tree fruits are starting to size up and many small fruits are setting. Grapes, the last of our major crops to bloom, are starting to open their flowers.

The continued dry weather should keep scab and fire blight risk at bay until the showers this weekend. Based on the RimPro models at the Romeo station, for which you can see you an overview by following the link, we will see continued risk for apple powdery mildew.

We continue to see insect movement, with populations of various aphids and mites climbing. A local scout reported first flight of obliquebanded leafroller at a warmer site in Oakland County in addition to continued sustained catch of codling moth above threshold even in mating disrupt blocks, San Jose scale males on traps, woolly apple aphid colonies, black cherry aphids and peach aphids. Plum curculio has been seen, but numbers remain low. Many mite pests also attack fruit crops and we have a mite control article updated in 2022 discussing different options for choosing miticides.

I encourage our growers to attend the weekly southern Michigan grower meetings virtually on Monday evenings by registering at Monday Night Southwest Michigan Fruit IPM Meeting 2023. 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 northern parts of the region, growers are still doing some chemical thinning. King fruit observed in Novi, Fenton and Romeo were in the 22–24 mm range, while in Almont we were still seeing fruitlets closer to 15 mm.

You may want to read this 2022 MSU Extension article on crop load management to prepare for whether and how you may want to treat your trees during and after bloom to ensure return bloom and marketable fruit size. If you are concerned about bitter pit (especially in Honeycrisp production), now would be the time to prepare for calcium sprays.

Apple fruitlets.
Apple fruitlets in Novi, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Blueberries in Fenton are past bloom and at full fruit set. In southwest Michigan, cranberry fruit worms continue to fly, and these can be a problem in blueberry crops. We are also at the time to start controlling for gall wasp in blueberries. The hot weather should slow down the start of spotted wing Drosophila development and early ripening cultivars may not need as many sprays.

Blueberry fruits.
Blueberry fruits starting to show color at Spicer’s Orchard in Fenton, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Brambles: We are seeing fruit set in red raspberries in Romeo and Fenton. There are floral buds on blackberry in Lenawee County. Early black raspberries in Washtenaw County are at full bloom.

Raspberry Fruits.
Raspberry fruit set in Fenton, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Cherries: Both sweet and tart cherries in Romeo and Fenton have hardened pits and further north in Almont the tart cherry pits have hardened in the last week. Sweet cherries in Romeo and Fenton are sizing up to 18 mm while tart cherries in Novi, Fenton and Romeo are around 15 mm. Both sweet and tart cherries in Fenton are starting to develop red color.

Tart cherries.
Tart cherries starting to develop color in Fenton, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Grapes: Wild grapes in Ray Township near Youngblood Vineyard started blooming in the last week, which is used as a biofix for grape berry moth. Grape berry moth damage on grape clusters on the edge of vineyards has been seen in southwest Michigan. Some cultivated vines have started to bloom in Fenton, while the earliest varieties (like Frontenac) have yet to bloom in Ray Township.

Wild grapes in bloom.
Wild grapes blooming in Ray Township, Michigan, June 5, 2023; Photo by Photo by Derek Plotkowski, MSU Extension.

Strawberries: We are seeing some fruit set in field strawberries in Romeo and Fenton.

Strawberries.
Fruit development in field strawberry in Fenton, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Peaches and nectarines: Growers in the area are starting to hand thin their peaches. Peach pits at Fenton and Romeo are still soft enough to be cut through with a knife with sizes up to 25 mm. It’s time to start thinking about your thinning strategies. Here is a 2006 article from Bill Shane and a more recent 2022 article from Penn State on the topic of thinning peaches.

Peaches.
Sliced peach fruitlet in Romeo, Michigan, June 5, 2023. Photo by Derek Plotkowski, MSU Extension.

Pears: European pear fruitlets observed at Novi are up to 15 mm. Some pear rust has appeared on the leaves as well.

Plums: European plums are well past bloom. The critical periods for most fungal control is for petal fall to late June, but for brown rot specifically the critical times are during bloom and later on at fruit coloring.

Disease conditions

With the continuing dry weathe,r our main disease concern is for apple powdery mildew. Although we are in a dry period now, our next wetting event has potential for being a large spore release event. We may get showers over the weekend, which could bring risk for apple scab and grape black rot.

Apple powdery mildew has been seen in the region, and the RimPro model indicates that we are in a period of high infection risk.

Apple scab has been reported in the region in susceptible cultivars and locations. Models indicate that most spores have already been released.

Insect conditions

With grape bloom imminent there is still time to review this 2022 article on reducing pesticide risks to bees during fruit crop bloom. As always, we implore you to avoid applying insecticides during bloom.

I have started to set up trap line traps for both the Michigan Department of Agriculture and Rural Development (MDARD) and MSU fruit research. These include traps for plum curculio, light brown apple moth, summer fruit tortrix moth, plum fruit moth, oriental cherry fruit fly, woolly apple aphid and San Jose scale in addition to scouting for spotted lanternfly. I will keep you up to date on these as needed.

In tree fruit our current insect concerns include plum curculio, scale, obliquebanded leafroller and codling moth. More in-depth information can be found by watching the latest weekly fruit meetings for southern Michigan on MSU’s Kaltura Mediaspace (these may take a few days to upload after the Monday meetings). The E-154 guide can be purchased here: https://shop.msu.edu/products/bulletin-e0154.

Aphids: Various aphids have been seen in our fruit crops so far this season. One of the primary ways they damage fruit crops is by producing honeydew that can lead to sooty mold growth. These can be found curled up in leaves or on the leaf undersides and prefer dry conditions with temperatures between 65-80 degrees Fahrenheit. Aphids protected by leaves are difficult to control.

Codling moth: We have had live catches of codling moth over threshold even in mating disrupt blocks. I have biofix set at May 18. The northern parts of the region may still have time to use selective products with ovicidal activity 100 growing degree days (GDD) base 50 after biofix.

Grape berry moth: This pest attacks developing grape clusters and has been seen in southwest Michigan. Wild grape bloom, which indicates biofix, is set at June 2. Second and third generation control are most effective at reducing infestations during harvest.

Obliquebanded leafroller: Local scouts have observed flight in warmer pasts of the region.

Plum curculio: Some adult plum curculios have been caught by a scout in the region. I have also caught some in Washtenaw and Saginaw counties. Scouting for fruit damage should occur before June drop.

San Jose scale: Some male San Jose scale have been seen on traps in the region and these numbers are higher in places that regularly see San Jose scale pressure. The next opportunity to control them is during their crawler stage around the second cover in apples.

Woolly apple aphid: Some have been observed by regional scouts, but management is usually done later in the summer.

Seasonal weather update

We haven’t seen any precipitation in the last week (see table) and temperatures have been climbing. The dry conditions from the last few weeks have put the southern parts of our region into “abnormally dry” conditions according to the U.S. Drought Monitor.

In the next week, we expect fair and dry conditions to continue through Friday, June 9, with highs in the low 80s and lows in the upper 40s and low 50s at night. We may see scattered showers over the weekend followed by a return to dry weather early next week.

Since we are past bloom in most fruit crops the dry weather should be favorable for cover sprays, but some sprays should not be used at high temperatures so as always look at your labels.

Liquid Precipitation Accumulation March 1 - June 6, 2023, issued June 6, 2023
Station (County) Rainfall Total (in.) Current Hours with Rainfall Current Rainfall Total Average (5 Yr.) Hours with Rainfall  Average (5 Yr.)
Commerce (Oakland) 7.8 168 8.6 172
Deerfield (Monroe) 7.1 155 9.4 177
East Lansing MSU Hort (Ingham) 7.8 173 8.1 169
Emmett (St. Clair) 8.6 166 6.2 179
Flint (Genesee) 8.1 163 7.6 174
Freeland (Saginaw) . . . .
Hudson (Lenawee) 5.5 146 9.7 193
Ithaca (Gratiot) 6.9 141 7.8 153
Lapeer (Lapeer) 4.2 116 7.4 166
Linwood (Bay) 6.8 133 8.2 164
Pigeon (Huron) 7.0 138 6.9 154
Richville/Frankenmuth (Tuscola) 6.5 137 6.8 149
Sandusky (Sanilac) 7.1 159 7.0 148
Romeo (Macomb) 8.1 168 7.5 155
Average of stations in this region: 7.0 151.0 7.8 165.7
Difference in Liquid Precipitation Accumulation from March 1 observed May 30 and June 6, 2023; issued May 30, 2023
Station (County) Rainfall Total (in.) May 30 Rainfall Total (in.) June 6 Difference from May 30- June 6 Hours with Rainfall May 30 Hours with Rainfall June 6 Difference from May 30- June 6
Commerce (Oakland) 7.8 7.8 0.0 168 168 0.0
Deerfield (Monroe) 7.1 7.1 0.0 155 155 0.0
East Lansing MSU Hort (Ingham) 7.8 7.8 0.0 173 173 0.0
Emmett (St. Clair) 8.6 8.6 0.0 166 166 0.0
Flint (Genesee) 8.1 8.1 0.0 163 163 0.0
Freeland (Saginaw) . . . . . .
Hudson (Lenawee) 5.5 5.5 0.0 146 146 0.0
Ithaca (Gratiot) 6.9 6.9 0.0 141 141 0.0
Lapeer (Lapeer) 4.2 4.2 0.0 116 116 0.0
Linwood (Bay) 6.8 6.8 0.0 133 133 0.0
Pigeon (Huron) 7.0 7.0 0.0 138 138 0.0
Richville/Frankenmuth (Tuscola) 6.5 6.5 0.0 137 137 0.0
Sandusky (Sanilac) 7.1 7.1 0.0 159 159 0.0
Romeo (Macomb) 8.1 8.1 0.0 168 168 0.0
Average of stations in this region: 7.0 7.0 0.0 151.0 151.0 0.0

The medium range guidance calls for normal to above-normal temperatures in the next two weeks with normal to below-normal precipitation.

Our regional average growing degree day accumulation for the season is very close has pulled just slightly ahead of the five-year average. Read this Michigan State University Extension article to learn more about degree days: Understanding growing degree-days.

GDD maps.

Degree Day Accumulation Mar. 1 - June 6, 2023, Forecast from June 7-June 12, 2023; issued June 6, 2023
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) 879 874 1012 720 715 835 505 492 592
Deerfield (Monroe) 970 993 1107 795 817 915 555 571 646
East Lansing MSU Hort (Ingham) 931 913 1067 767 749 885 543 518 633
Emmett (St. Clair) 820 811 945 666 658 772 458 447 536
Flint (Genesee) 961 951 1092 791 784 905 560 548 646
Freeland (Saginaw) 849 850 978 690 695 802 476 478 559
Hudson (Lenawee) 931 911 1072 767 747 889 544 517 637
Ithaca (Gratiot) 968 888 1105 803 730 922 574 505 664
Lapeer (Lapeer) 872 877 995 713 719 818 499 498 578
Linwood (Bay) 792 787 916 640 638 745 438 432 515
Pigeon (Huron) 798 758 931 646 614 762 444 417 529
Richville/Frankenmuth (Tuscola) 949 895 1080 783 737 897 557 512 642
Sandusky (Sanilac) 826 792 950 673 646 779 465 442 542
Romeo (Macomb) 893 891 1021 731 729 841 507 503 588
Average of stations in this region: 889 871 1019 728 713 841 509 491 593
Difference in Degree Day Accumulation from Mar. 1 observed May 30, and June 6, 2023; issued June 6, 2023
Station (County) Degree Days Base 42°F  May 30 Degree Days Base 42°F  June 6 Degree Days Base 42°F Difference Degree Days Base 45°F May 30 Degree Days Base 45°F June 6 Degree Days Base 45°F Difference Degree Days Base 50°F May 30 Degree Days Base 50°F June 6 Degree Days Base 50°F Difference
Commerce (Oakland) 690 879 189.0 552 720 168.0 373 505 132.0
Deerfield (Monroe) 780 970 190.0 626 795 169.0 421 555 134.0
East Lansing MSU Hort (Ingham) 732 931 199.0 589 767 178.0 401 543 142.0
Emmett (St. Clair) 649 820 171.0 515 666 151.0 341 458 117.0
Flint (Genesee) 762 961 199.0 613 791 178.0 417 560 143.0
Freeland (Saginaw) 667 849 182.0 530 690 160.0 350 476 126.0
Hudson (Lenawee) 739 931 192.0 595 767 172.0 408 544 136.0
Ithaca (Gratiot) 756 968 212.0 612 803 191.0 418 574 156.0
Lapeer (Lapeer) 697 872 175.0 558 713 155.0 378 499 121.0
Linwood (Bay) 612 792 180.0 481 640 159.0 314 438 124.0
Pigeon (Huron) 618 798 180.0 487 646 159.0 320 444 124.0
Richville/Frankenmuth (Tuscola) 745 949 204.0 600 783 183.0 409 557 148.0
Sandusky (Sanilac) 642 826 184.0 510 673 163.0 337 465 128.0
Romeo (Macomb) 702 893 191.0 561 731 170.0 372 507 135.0
Average of stations in this region: 699 889 189 559 728 168 376 509 133

Watch Jeff Andresen's weekly 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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