Southeast Michigan fruit update – June 20, 2023
Growers in southeast Michigan are preparing for cherry harvest and spotted wing Drosophila.
Welcome to the 11th 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.
Last week we had severe weather, including a hail event that caused some damage in the region. Hail damage in particular brings about high risk for fungal disease and should be followed up with a timely fungicide spray. Despite the severe weather, our overall precipitation total remains low and our region remains in a state of either “abnormally dry” or “moderate drought” 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. We do have more rain in the forecast, though it won’t be enough to pull us out of drought conditions.
While strawberry harvest is well under way, we have some growers starting to pick sweet cherries and red raspberries are nearly ready as well. It is time to start thinking about ethephon sprays for tart cherries to prepare for harvest.
While southwest Michigan is out of primary scab season, we still have the potential for some final spore releases with the coming rain. 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. Rusty spot has been seen in peaches in the region.
Not much has changed with insects in the past week, with populations of various aphids and mites climbing. It is time to start thinking about spotted wing drosophila control and rereading some of the SWD factsheets that MSU Extension has put out. Oblique banded leaf rollers are being caught regularly, so you may want to read this recent article on OBLR management by Julianna Wilson and John Wise. There is continued sustained catch of codling moth above threshold even in mating disrupt blocks. We are past the window for San Jose Scale crawler control, though there could still be time in northern parts of the region.
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 Mediaspace (these may take a few days to upload after the Monday meetings).
Apples: June drop is underway and in places that are still hanging on to fruit you can usually see which apples are staying and which are dropping. King fruit observed in Novi, Fenton, and Romeo were sizing up to 40 millimeters.
Blueberries: Blueberries in Fenton are past bloom and at full fruit set. In southwest Michigan some deepening of color has started, but we are not that far in our region. We are also at the time to start controlling for gall wasp in blueberries.
Brambles: We are seeing ripening fruit in red raspberries in Romeo and Fenton. Blackberries are flowering in Lenawee County.
Cherries: Some varieties of sweet cherries are being harvested in Britton and Fenton and they are getting close to harvest around the region. Tart cherries have mostly turned red and are starting to soften. Many growers are taking steps to repel birds and it is time to start thinking about ethephon sprays.
Grapes: Fruit set is happening most varieties in Fenton and Ray Township with some later cultivars like Petite Pearl still blooming.
Strawberries: U-picks are open at several sites. Most sites are starting to see ripe fruit. Renovation should start as soon as harvest is finished.
Peaches and nectarines: Most growers have gone through their first round of hand thinning peaches. Peach pits at Fenton and Romeo are still soft enough to be cut through with a knife, but those pits are firming up. Fruit sizes are being seen up to 30 millimeters.
Pears: European pear fruitlets observed at Novi are up to 25 millimeters. 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.
While southwest Michigan is out of primary scab season, we still have the potential for some final spore releases with the coming rain we expect this week. In addition to apple scab it could encourage 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, but we are not quite at the end of primary scab season. Primary scab season ends when the last of the ascospores are ejected and this is projected to continue through next week.
Peach rusty spot has been seen in the region.
In tree fruit we are starting to prepare for summer pests like spotted wing drosophila and apple maggot. 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. These include woolly apple aphids, rosy apple aphids
Apple Maggot: Scouts will be putting traps up soon. There is no action to be taken yet.
Codling Moth: We have had high catches of codling moth over threshold even in mating disrupt blocks. I have biofix set at May 18. We are past the time for ovicidal sprays.
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.
Oblique Banded Leaf Roller: These are being seen across the region, though most growers won’t be at threshold for action yet. To be prepared for action, read this recent article on OBLR control by Julianna Wilson and John Wise.
Plum Curculio: Scouting for fruit damage should occur before June drop.
San Jose Scale: The window for control is over and scales will be starting to wax up. Not much damage has been seen in the region so far this year.
Woolly Apple Aphid: Some have been observed by regional scouts, but management is usually done later in the summer.
Seasonal weather update
Although we have seen a little rain and severe weather, the overall lack of precipitation has put the majority of our region into “moderate drought” according to the U.S. Drought Monitor. MSU Extension has a collection of articles related to drought on its drought resources page. We do have more rain in the forecast, though it won’t be enough to take us out of drought conditions.
In the next week we expect mostly sunny, warm, and dry weather. Scattered showers are possible on Friday and Saturday with thunderstorms potentially happening later in the weekend. High temperatures will stay in the mid to upper 80s F until the end of the week when they will drop to the upper 70s F. Lows will be in the 50s F and 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 - June 20, 2023, issued June 20, 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)||8.4||184||10.2||191|
|Emmett (St. Clair)||10.7||196||8.4||209|
|Average of stations in this region:||8.0||170.5||9.5||188.3|
|Difference in Liquid Precipitation Accumulation from Mar. 1 observed June 13 and June 20, 2023; issued June 20, 2023|
|Station (County)||Rainfall Total (in.) June 13||Rainfall Total (in.) June 20||Difference from June 13-June 20||Hours with Rainfall June 13||Hours with Rainfall June 20||Difference from June 13-June 20|
|East Lansing MSU Hort (Ingham)||8.0||8.4||0.4||178||184||6.0|
|Emmett (St. Clair)||9.5||10.7||1.2||184||196||12.0|
|Average of stations in this region:||7.5||8.0||0.5||162.1||170.5||8.4|
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 (GDD) accumulation for the season has once again dropped slightly below the five-year average. Read this Michigan State University Extension article to learn more about degree days: Understanding growing degree-days.
|Degree Day Accumulation Mar. 1 - June 20, 2023, Forecast from June 21-June 26, 2023; issued June 20, 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)||1224||1274||1274||1019||1069||1069||732||769||769|
|Emmett (St. Clair)||1081||1139||1248||884||945||1033||612||666||731|
|Average of stations in this region:||1176||1225||1342||973||1025||1123||688||735||810|
|Difference in Degree Day Accumulation from Mar. 1 observed June 13, and June 20, 2023; issued June 20, 2023|
|Station (County)||Degree Days Base 42 F June 13||Degree Days Base 42 F June 20||Degree Days Base 42 F Difference||Degree Days Base 45 F June 13||Degree Days Base 45 F June 20||Degree Days Base 45 F Difference||Degree Days Base 50 F June 13||Degree Days Base 50 F June 20||Degree Days Base 50 F Difference|
|East Lansing MSU Hort (Ingham)||1053||1224||171.0||870||1019||149.0||617||732||115.0|
|Emmett (St. Clair)||943||1081||138.0||767||884||117.0||528||612||84.0|
|Average of stations in this region:||1014||1176||161||833||973||140||583||688||105|
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.