Southeast Michigan fruit update – May 30, 2023
Fruit set in tree fruit, small fruit bloom, dry weather.
Welcome to the eighth 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.
When I was making the tables for the weather summary, I thought I made a mistake because the weather stations all reported no change in total precipitation in the last week, but there was no mistake. The dry weather we have been having is expected to continue in the coming weeks while temperatures will rise. Many of you have been irrigating your crops for some time and I expect that to continue for the foreseeable future.
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.
The continued dry weather should keep scab and fire blight risk at bay. 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. I have received reports of some mild powdery mildew on apples in parts of orchards. If you are having trouble with spraying, I highly recommend looking into the free resource Airblast 101.
We have started to see more insect movement in the last week and I have begun to monitor traps for invasive species. I have received reports of sustained catch of codling moth above threshold even in mating disrupt blocks, San Jose Scale males on traps, and woolly apple aphid colonies starting. We have yet to see flight in oblique banded leaf rollers. Plum curculio has been seen, but numbers remain low. In addition to insect movement, we are also seeing more activity from mammals like deer. Make sure to do your normal preparations for protection from animal damage.
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).
Apples: In southern parts of the region (Deerfield up to Novi) growers are doing late window thinning. King fruit observed at Novi ranged from 13.5 mm in Buckeye Gala to 22 mm in IdaRed. In Fenton and Romeo most fruitlets were in the 15-16 mm range while in Almont we were still seeing 8-9 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.
Blueberries:Blueberries in Fenton range from some varieties hanging on to blooms to full fruit set. In southwest Michigan cranberry fruit worm adults are starting to fly, and these can be a problem in blueberry crops.
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.
Cherries: Both sweet and tart cherries in Romeo and Fenton have hardened pits, while further north in Almont tart cherries have pits that can be easily sliced through with a knife. Sweet cherries in Romeo and Fenton are sizing up to 16 mm while tart cherries in Novi, Fenton and Romeo are around 13-15 mm.
Grapes: We have seen plentiful shoot growth in Fenton and Ray Township in addition to swelling inflorescences. Some of the individual flower buds are starting to separate, but we have yet to see bloom in cultivated or wild grapes in the region.inflorescences. We saw some cold damage last week in some cultivars in Ray Township.
Strawberries: We are seeing some fruit set in field strawberries in Romeo and Fenton.
Peaches and nectarines: Peach pits at Fenton and Romeo are still soft enough to be cut through with a knife with sizes up to 13.5 mm. It’s time to start thinking about your thinning strategies. Here is a 2006 article from MSU Extension and a more recent 2022 article from Penn State on the topic of thinning peaches.
Pears: European pear fruitlets observed at Novi are up to 14 mm.
Plums: uropean 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. but for brown rot specifically the critical times are during bloom and later on at fruit coloring.
With the upcoming dry weather, we don’t expect infection periods for apple/pear scab, fire blight, grape black rot, or apple canker. Although we are in a dry period now, our next wetting event has potential for being a large spore release event.
Apple powdery mildew has been seen in the region, and the RimPro model indicates that we are in a period of high infection risk. but reports indicate it is mild.
Apple scab has been reported in the region in susceptible cultivars and locations.
With small fruit bloom continuing 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 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, wooly 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, tarnished plant bug, green fruit worm, oriental fruit moth, oblique banded leaf roller, and codling moth. 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). The E-154 guide can be purchased at the MSU Bookstore.
Black stem borer: Main control is to target emerging females as they search for new sites to deposit eggs, which should be in the coming weeks.
Codling moth: We have had live catches of codling moth over the last week (though I received a report from a grower of it being caught earlier). I have biofix set at May 18. The next chance for control is to use selective products with ovicidal activity 100 growing degree days (GDD) base 50 after biofix (forecasted in about a week).
Grape Berry Moth: This pest attacks developing grape clusters. Watch for wild grape bloom to indicate biofix (expected in the next week). Second and third generation control are most effective at reducing infestations during harvest.
Oblique Banded Leaf Roller: A few larvae have been seen by scouts, but no observed flight.
Oriental Fruit Moth: We have had sustained catches in the region (biofix May 11). Products with ovicidal activity are suggested for about 100-150 GDD (45) after biofix (should be your next cover if not already applied).
Pear Psylla: We are past the time for early control with dormant oil. Later on control requires the reduction of vegetative flushes and the hand removal of suckers.
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.
Redbanded Leaf Roller: Numbers are falling in the region. The first flight is likely done and many would have been controlled by petal fall sprays.
Rosy Apple Aphid: Can be seen curled in leaves around the region.
San Jose Scale: Some male SJS have been seen on traps in the region. 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. Due to low humidity our night time temperatures have stayed quite cool, but we may have more moisture in the air in the coming days. The dry weather and high potential evaporation rates since the beginning of the month has been pushing our soil moisture down. This is forecast to continue through the second week of June.
In the next week we expect fair and dry conditions to continue with highs in the low 90s degrees Fahrenheit and lows in the low 60s F at night.
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 Mar. 1 - May 30, 2023, issued May 30, 2023|
|Station (County)||Rainfall Total (in.) Current||Hours with Rainfall Current||Rainfall Total Average (5 Yr.)||Hours with Rainfall Average (5 Yr.)|
|East Lansing MSU Hort (Ingham)||7.8||173||7.7||162|
|Emmett (St. Clair)||8.6||166||6.0||175|
|Average of stations in this region:||7.0||151.0||7.3||158.8|
|Difference in Liquid Precipitation Accumulation from Mar. 1 observed May 22 and May 30, 2023; issued May 30, 2023|
|Station (County)||Rainfall Total (in.) May 22||Rainfall Total (in.) May 30||Difference from May 22-May 30||Hours with Rainfall May 22||Hours with Rainfall May 30||Difference from May 22-May 30|
|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|
|Average of stations in this region:||7.0||7.0||0.0||151.0||151.0||0.0|
The medium range guidance calls for drier than normal weather with above normal temperatures, with both shifting back to normal levels by mid-June.
The long lead outlooks are still calling for wetter than normal conditions for the late spring and summer seasons, but these forecasts have shifted towards expected normal temperatures.
Our regional average growing degree day accumulation for the season is very close to the 5-year average. Read this Michigan State University Extension article to learn more about degree days: Understanding growing degree-days.
|Degree Day Accumulation Mar. 1 - May 30, 2023, Forecast from May 31-June 5, 2023; issued May 30, 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|
|East Lansing MSU Hort (Ingham)||732||746||928||589||604||768||401||406||549|
|Emmett (St. Clair)||649||658||825||515||526||673||341||348||469|
|Average of stations in this region:||699||707||887||559||569||729||376||382||
|Difference in Degree Day Accumulation from Mar. 1 observed May 22, and May 30, 2023; issued May 30, 2023|
|Station (County)||Degree Days Base 42 F May 22||Degree Days Base 42 F May 30-||Degree Days Base 42 F Difference||Degree Days Base 45 F May 22||Degree Days Base 45 F May 30||Degree Days Base 45 F Difference||Degree Days Base 50 F May 22||Degree Days Base 50 F May 30||Degree Days Base 50 F Difference|
|East Lansing MSU Hort (Ingham)||580||732||152.0||459||589||130.0||303||401||98.0|
|Emmett (St. Clair)||515||649||134.0||402||515||113.0||258||341||83.0|
|Average of stations in this region:||550||699||149||431||559||128||280||376||95|
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.