Southeast Michigan fruit update – June 13, 2023
June drop, drought conditions, strawberry time.
Welcome to the 10th 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.
It feels funny writing about drought conditions with rain falling outside my window, but even the rain from this weekend hasn’t been enough to pull us out of what the National Oceanic and Atmospheric Administration (NOAA) calls a “flash drought” where low precipitation combined with high temperatures and wind cause a rapid onset of drought conditions. The weather here has put the southern parts of our region into “moderate drought” conditions and the majority of the state in “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. We do have more rain in the forecast, fortunately.
We are starting our first harvest of fruit in the region with some farms opening already for U-pick strawberries. Tree fruits continue to size up and sweet cherries are turning red and starting to soften. Grapes, the last of our major crops to bloom, are getting to berry set in some of the earlier-blooming cultivars.
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. Obliquebanded leafrollers are being caught regularly in addition to continued sustained catch of codling moth above threshold even in mating disrupt blocks. San Jose scale crawlers are also about and the window for control can be pretty tight. Plum curculio damage has been seen along woodlines, but overall seems to be mild. Many mite pests, like European red mite and twospotted spider mite, also attack fruit crops. 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 Mediaspace (these may take a few days to upload after the Monday meetings).
Apples: In southern parts of the region, June drop is underway. You can already see which apples are staying and which are dropping. King fruit observed in Novi, Fenton and Romeo were in the 28-30 mm range, while further north we were still seeing fruitlets closer to 21 mm.
Blueberries: Blueberries in Fenton are past bloom and at full fruit set. In southwest Michigan, cranberry fruitworms continue to fly. These can be a problem in blueberry crops. We are also at the time to start controlling for gall wasp in blueberries.
Brambles: We are seeing fruit set in red raspberries in Romeo and Fenton. Blackberries are flowering in Lenawee County.
Cherries: Sweet cherries in Britton, Romeo and Fenton have turned red and are starting to soften. Some blush is visible on tart cherries in Fenton, but for most places tart cherries remain green and range from 12 – 16 mm.
Grapes: Frontenac in Ray Township has bloomed and started fruit set. Later varieties like Petite Pearl are opening up. Wild grape bloom has finished.
Strawberries: U-picks have started to open at some sites. Most sites are starting to see ripe fruit.
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 30 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.
Pears: European pear fruitlets observed at Novi are up to 25 mm. Some pear rust has appeared on the leaves as well. Asian pears observed in Macomb Township were at 30 mm.
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.
The recent rains resulted in a large apple scab spore release event after a long dry period. We expect a few more showers this week, 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, 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.
As discussed at last night’s grower meeting, we may have some strikes of raspberry fire blight. These canes should be removed and destroyed with regular disinfection of tools. For more information, see this MSU Extension article on fire blight in brambles.
In tree fruit, our current insect concerns include San Jose 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. These include woolly apple aphids, rosy apple aphids
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.
Dock sawfly: We saw some damage from dock sawfly in apples in the region. Typically, control for this pest is linked to weed management.
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.
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. These numbers are higher in places that regularly see San Jose scale pressure. This is the window for control and an effective insecticide should be used before they start to wax up.
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, the dry weather here has put the southern parts of our region into moderate drought conditions and the majority of the state in abnormally dry 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, fortunately.
In the next week, we expect mostly cloudy conditions with some scattered showers on Tuesday, Thursday, and over the weekend. High temperatures will climb back into the low 80s by the end of the week with lows in the mid-40s and low 50s at night.
Since we are past bloom in most fruit crops, the dry weather should be favorable for cover sprays. Some sprays should not be used at high temperatures, so as always look at your labels.
|Liquid Precipitation Accumulation Mar. 1 - June 13, 2023, issued June 13, 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)||8.0||178||9.4||182|
|Emmett (St. Clair)||9.5||184||7.4||193|
|Average of stations in this region:||7.5||162.1||8.9||178.6|
|Difference in Liquid Precipitation Accumulation from Mar. 1 observed June 6 and June 13, 2023; issued June 13, 2023|
|Station (County)||Rainfall Total (in.) June 6||Rainfall Total (in.) June 13||Difference from June 6-June 13||Hours with Rainfall June 6||Hours with Rainfall June 13||Difference from June 6-June 13|
|East Lansing MSU Hort (Ingham)||7.8||8.0||0.1||173||178||5.0|
|Emmett (St. Clair)||8.6||9.5||0.9||166||184||18.0|
|Average of stations in this region:||7.0||7.5||0.5||151.0||162.1||11.1|
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 13, 2023, Forecast from June 14-June 19, 2023; issued June 13, 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)||1053||1088||1203||870||904||1002||617||639||720|
|Emmett (St. Clair)||943||970||1078||767||797||885||528||552||616|
|Average of stations in this region:||1014||1043||1161||833||864||962||583||609||682|
|Difference in Degree Day Accumulation from Mar. 1 observed June 6, and June 13, 2023; issued June 13, 2023|
|Station (County)||Degree Days Base 42°F June 6||Degree Days Base 42°F June 13||Degree Days Base 42°F Difference||Degree Days Base 45°F June 6||Degree Days Base 45°F June 13||Degree Days Base 45°F Difference||Degree Days Base 50°F June 6||Degree Days Base 50°F June 13||Degree Days Base 50°F Difference|
|East Lansing MSU Hort (Ingham)||931||1053||122.0||767||870||103.0||543||617||74.0|
|Emmett (St. Clair)||820||943||123.0||666||767||101.0||458||528||70.0|
|Average of stations in this region:||889||1014||126||728||833||105||509||583||74|
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.