Southeast Michigan fruit update – June 27, 2023
Cherries and raspberries are being harvested and strawberries are wrapping up. Growers are preparing for Spotted Wing Drosophila.
Welcome to the 12th 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.
These days are a bit hazy with smoke coming in from wildfires in Canada. This should clear up in the coming days, but we will continue to have cloudy conditions with showers from mid-week through the weekend.
Despite recent wet weather, our overall precipitation total remains low and our region remains in a state of “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.
Many growers have wrapped up strawberry harvest and will begin renovation soon. Sweet cherries are also off the trees in warmer parts of the region and I have seen both tart cherries and red raspberries for sale at local farms. For some growers there is still time to put ethephon sprays to simplify tart cherry harvest.
While southwest Michigan is out of primary scab season, RimPro models are still showing potential for some small spore releases through July 1. Recent cover sprays should last long enough to protect the trees. Most growers seem to have scab under control this season and I haven’t seen much out in the field. 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. Though scouts haven’t been seeing much spotted wing drosophila yet this season, I have gotten secondhand reports of some infestations. The development of SWD this seasons seems to have been delayed by the dry weather, but it is time to plan for your spotted wing drosophila control methods. Here is a collection of 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.
This week was the last of our Southern Michigan Fruit IPM weekly meetings. 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 mostly complete. King fruit observed in Novi, Fenton, Britton, and Romeo were sizing up to 50 millimeters.
Blueberries: Blueberries in Fenton at full fruit set. In southwest Michigan some deepening of color has started, but we are not that far in our region. Fungicides for anthracnose, Alternaria, and Botrytis should be included in your sprays in addition to sprays to protect against SWD. Blueberry maggot has been captured in southwest Michigan.
Brambles: We are seeing growers harvest red raspberries in Romeo, Fenton, and Britton Blackberries are setting in Lenawee County. Growers should continue to protect plants from anthracnose and spur blights.
Cherries: Most sweet cherries are either harvested or will be picked soon. Some growers have started to harvest tart cherries. Many growers are taking steps to repel birds and in cooler areas there is still time to use ethephon sprays.
Grapes: Fruit set is happening most varieties in Fenton and Ray Township with some earlier cultivars already at pea sized fruit. Some of our discussion on the fruit team has been about smoke taint, which can often be a problem in wine in areas prone to wildfires. Some winemakers in our region may be interested to read up on some smoke taint resources, though we are not likely to have enough smoke exposure to cause noticeable changes.
Strawberries: Many U-picks are still open, though some are already wrapping up harvest. 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. The earliest peaches in the region will be picked as early as the end of next week.
Pears: European pear fruitlets observed at Novi are up to 30 millimeters. Some pear rust has appeared on the leaves as well.
Plums: 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 July 1.
Fire blight strikes have been seen in the region. For shoot blight strikes should be pruned out
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.
Apple maggot: Scouts have started to monitor. There is no action to be taken yet.
Codling moth: Numbers seem to have dropped in response to cover sprays. We are past peak egg laying and first flight is coming to an end.
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. We would expect to see the next generation around 1250 GDD base 50 (810 GDD after the biofix, we were at 507 GDD base 50 on June 6). Second and third generation control are most effective at reducing infestations during harvest.
Obliquebanded leafroller: 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: Some egg hatching has been reported in southwest Michigan.
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.
Spotted wing Drosophila: Scouts in southeast Michigan have yet to report any catches and SWD development was likely delayed by the hot and dry weather. I have gotten some secondhand reports of SWD in the area and it is time to start treating susceptible crops like blueberries. Familiarize yourself with information on our SWD factsheets page. More information can be found in the meeting recording (see above)
Woolly apple aphid: These have started to move to terminals.
Seasonal weather update
These days are a bit hazy with smoke coming in from wildfires in Canada. This should clear up in the coming days, but we will continue to have cloudy conditions with showers from mid-week through the weekend. High temperatures will range from the low 70s degrees Fahrenheit midweek to the 80s F over the weekend. Low temperatures will range from the 50s F midweek to the low 60s F over the weekend.
Despite recent wet weather, our overall precipitation total remains low and our region remains in a state of “moderate drought” conditions 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 pull us out of drought conditions.
|Liquid Precipitation Accumulation Mar. 1 - June 26, 2023, issued June 26, 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)||8.6||190||11.5||204|
|Emmett (St. Clair)||11.5||217||9.4||219|
|Average of stations in this region:||8.7||182.5||10.4||198.6|
|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 20||Rainfall Total (in.) June 26||Difference from June 20-June 26||Hours with Rainfall June 20||Hours with Rainfall June 26||Difference from June 20-June 26|
|East Lansing MSU Hort (Ingham)||8.4||8.6||0.2||184||190||6.0|
|Emmett (St. Clair)||10.7||11.5||0.8||196||217||21.0|
|Average of stations in this region:||8.0||8.7||0.7||170.5||182.5||11.9|
The medium range guidance calls for normal to above-normal temperatures in the next two weeks with normal to above-normal precipitation.
Our regional average growing degree day accumulation for the season has once again dropped slightly below 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 - June 26, 2023, Forecast from June 27-July 2, 2023; issued June 26, 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)||1398||1431||1566||1175||1208||1326||857||879||978|
|Emmett (St. Clair)||1238||1297||1393||1023||1085||1160||721||777||828|
|Average of stations in this region:||1346||1384||1509||1125||1166||1271||810||847||926|
|Difference in Degree Day Accumulation from Mar. 1 observed June 20, and June 26, 2023; issued June 26, 2023|
|Station (County)||Degree Days Base 42 F June 20||Degree Days Base 42 F June 26||Degree Days Base 42 F Difference||Degree Days Base 45 F June 20||Degree Days Base 45 F June 26||Degree Days Base 45 F Difference||Degree Days Base 50 F June 20||Degree Days Base 50 F June 26||Degree Days Base 50 F Difference|
|East Lansing MSU Hort (Ingham)||1224||1398||174.0||1019||1175||156.0||732||857||125.0|
|Emmett (St. Clair)||1081||1238||157.0||884||1023||139.0||612||721||109.0|
|Average of stations in this region:||1176||1346||170||973||1125||152||688||810||122|
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.