Southeast Michigan fruit update- July 18, 2023
Continuing harvests, spotted wing Drosophila catches, and preparing for brown marmorated stink bug.
Welcome to the 15th 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.
The last week brought considerable rainfall, which helps to provide relief from the dryness from earlier in the season. Despite that, our region remains in a state of abnormally dry to moderate drought conditions according to the U.S. Drought Monitor. We expect some more rain later in the week, though likely less than we saw in the last week.
Our early season crops like strawberries and cherries have mostly wrapped up and we are on to our midseason crops. The first peaches in the region have been seen in markets, some blueberry u-picks are open, and red and black raspberries are available. If you haven’t renovated your strawberry fields this should be done very soon.
Based on the RimPro models at the Romeo station, we will see continued risk for apple powdery mildew. We are past primary scab season. There is also risk this week for grape black rot and grape powdery mildew.
Apple maggot, brown marmorated stink bug, cherry fruit fly and spotted wing Drosophila (SWD) have been caught in the region. SWD infestations can still be present when catches are low and the damage from SWD can be extensive enough that for many growers it makes sense to treat susceptible crops even if there are low counts in traps. Here is a collection of SWD fact sheets that MSU Extension has put out. We are starting to see brown marmorated stink bug, which can be a particular problem in peaches and apples. A good way to prepare for it this season is to read this management fact sheet for brown marmorated stink bug in Michigan.
Our Southern Michigan Fruit IPM weekly meetings wrapped up at the end of June. The back catalog of the weekly fruit meetings for southern Michigan can be seen on MSU’s Kaltura Media Space.
Apples: King fruit observed in Fenton and Romeo were sizing up to 60 mm. Apple maggot has been caught in the region as well as codling moth second flight. Some terminal fireblight has been seen in the region, especially in locations where there was physical damage (like hail). Infected branches should be removed 12-18 inches below visible damage and instruments should be sanitized between cuts. Here is some practical management information from Washington State Extension.
Blueberries: The first blueberry fields are open for u-pick in Fenton. In later varieties, there is still time to use fungicides for anthracnose, Alternaria and Botrytis 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 as well as black raspberries in Washtenaw County. Blackberries are setting in Lenawee County and some were even ready to harvest in Detroit. Continue to protect plants from anthracnose and spur blights.
Cherries: Most sweet cherries are harvested. Tart cherry harvest continues with continued need to take steps to repel birds.
Grapes: We are seeing berry touch in tight-clustered cultivars in Fenton and Ray Townships. Some growers have set large crops that may need thinning or cluster removal, which can be done midsummer.
Strawberries: Some growers are still picking, though many are already wrapping up harvest. Renovation should start as soon as harvest is finished.
Peaches and nectarines: The earliest peaches (Rich May, Desiree) are being harvested in Southern parts of the region. Peach pits of free stone peaches at Fenton and Romeo at pit hardening. Peaches undergo a second round of growth from cell expansion at this stage.
Pears: European pear fruitlets continue to grow. Asian pears in Macomb Township were observed up to 40 mm.
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.
Apple powdery mildew has been seen in the region. The RimPro model indicates we are entering another period of high infection risk. Here is a link for a 2010 article on what to do with current apple powdery mildew infection. As always with older articles, cross check the recommendations for chemicals with the current E-154 guide.
Apple scab has been reported in the region in susceptible cultivars and locations. We are past the primary scab infection window. If scab is present in your orchard you may need to spray to prevent secondary infections.
Fire blight strikes have been seen in the region, especially in areas with recurring infections and areas that experienced physical damage. For shoot blight, strikes should be pruned out with cuts 12-18 inches below visible damage and instruments should be sanitized between cuts. Here is some practical management information from Washington State Extension.
We have the potential for some grape black rot with the rain we expect this week.
Pear rust is primarily controlled by separation of juniper species from pear plantings (much like cedar apple rust). Symptoms appear on pears in summer, but most control needs to happen early in the season when galls appear on junipers (around May).
Peach rusty spot has been seen in the region.
Scouts are seeing sooty blotch in the centers of trees with large canopies, but not in high-density orchards with good spray penetration.
Apple maggot: Scouts have seen these around the region. Areas that usually have high pressure are seeing high counts, but numbers are also climbing elsewhere.
Brown marmorated stink bug: We are seeing our first catches of brown marmorated stink bug. Early control is key here because they will continue to be a pest up until harvest when sprays are not possible because of preharvest intervals.
Cherry fruit fly: First caught June 18 in the region, but numbers have been low. Mostly present in sites that have had problems with the pest before.
Codling moth: Areas with high pressure are seeing regular numbers. The second flight has started, though in conventionally managed sites the numbers are staying relatively low.
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 1,250 growing degree days (GDD) base 50, which happened last week in warmer parts of the region and will happen in the next week in the rest. Second and third generation control are most effective at reducing infestations during harvest.
Obliquebanded leafroller: Number seem low across the region at the moment because we may be between generations. To be prepared for action, read this recent article on obliquebanded leafroller control by Julianna Wilson and John Wise.
Oriental fruit moth: Catches were higher this week, mostly between four and five moths in each trap.
Plum curculio: This time of summer will be egg hatching.
Phylloxera: Galls mostly being seen in susceptible cultivars near woodlines with wild grapes.
San Jose scale: The window for control is over and scales will already be waxed up. Not much damage has been seen in the region so far this year.
Spotted wing Drosophila: Scouts in southeast Michigan caught some SWD in grapes and raspberries. Numbers are low in northwest and west-central Michigan, but larvae populations are building in unsprayed blocks. Continue to treat susceptible crops like blueberries. Familiarize yourself with information on our SWD factsheets page.
Woolly apple aphid: These have started to move to terminals and are heavy in some places, particularly in orchards with larger canopy trees.
Seasonal weather update
There will be a chance of showers throughout the week, though we shouldn’t get as much precipitation as last week. Overall temperatures will be warmer with highs mostly in the mid-80s. Low temperatures will drop to the mid-60s.
Despite recent wet weather (about 2.5 inches of rain last week), the region remains in a state of abnormally dry to 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.
|Liquid Precipitation Accumulation Mar. 1 - July 18, 2023, issued July 18, 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)||13.1||222||12.2||224|
|Emmett (St. Clair)||17.2||269||11.3||244|
|Average of stations in this region:||13.0||223.4||12.0||219.7|
|Difference in Liquid Precipitation Accumulation from Mar. 1 observed July 5 and July 18, 2023; issued July 18, 2023|
|Station (County)||Rainfall Total (in.) July 11||Rainfall Total (in.) July 18||Difference from July 11-July 18||Hours with Rainfall July 11||Hours with Rainfall July 11||Difference from July 11-July 18|
|East Lansing MSU Hort (Ingham)||10.7||13.1||2.4||207||222||15.0|
|Emmett (St. Clair)||13.7||17.2||3.5||253||269||16.0|
|Average of stations in this region:||10.5||13.0||2.5||206.3||223.4||17.1|
The medium range guidance calls for cooler than normal temperatures with near normal precipitation in the next couple weeks.
Our regional average growing degree day accumulation is fairly close to the five-year average.
|Degree Day Accumulation Mar. 1 - July 18, 2023, Forecast from June 19-July 24, 2023; issued July 18, 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)||2012||2129||2188||1723||1836||1882||1296||1394||1424|
|Emmett (St. Clair)||1788||1946||1956||1508||1668||1658||1095||1251||1215|
|Average of stations in this region:||1948||2060||2123||1661||1783||1819||1237||1347||1364|
|Difference in Degree Day Accumulation from Mar. 1 observed July 11, and July 18, 2023; issued July 18, 2023|
|Station (County)||Degree Days Base 42°F July 11||Degree Days Base 42°F July 18||Degree Days Base 42°F Difference||Degree Days Base 45°F July 11||Degree Days Base 45°F July 18||Degree Days Base 45°F Difference||Degree Days Base 50°F July 11||Degree Days Base 50°F July 18||Degree Days Base 50°F Difference|
|East Lansing MSU Hort (Ingham)||1831||2012||181.0||1564||1723||159.0||1171||1296||125.0|
|Emmett (St. Clair)||1633||1788||155.0||1374||1508||134.0||996||1095||99.0|
|Average of stations in this region:||1772||1948||176||1507||1661||154||1117||1237||120|
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.