Southeast Michigan fruit update- July 5, 2023
Growers are harvesting cherries and preparing for spotted wing Drosophila.
Welcome to the 13th 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 is certainly nice to have clear air once again after a week of smoke. In last week's update, I included some information about smoke taint in grapes (which is only a problem that surfaces after fermentation into wine). Another extension educator sent me this article on the effects of wildfire smoke on crops and workers from the University of Minnesota Extension. While we are currently past the most recent period of haze without affecting our farms much (except perhaps deterring some U-pick customers), it could be helpful to read up on what some of the implications of the wildfires could be.
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 are expecting a little more rain this week in addition to warm temperatures
Right now is peak time for harvesting tart cherries and the first crop of red raspberries. Most sweet cherries are off the trees, though some growers are seeing cracking from recent rain in their later crops. The earliest peach cultivars will be harvested this week as well. Many growers are done with their strawberry harvest and are getting ready to renovate.
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 are past primary scab season. There is also risk this week for grape black rot and grape powdery mildew. Rusty spot has been seen in peaches in the region.
Apple maggot and cherry fruit flies have been caught in the region. 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 season 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.
Last 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 Media Space (these may take a few days to upload after the Monday meetings).
Apples: King fruit observed in Fenton and Romeo were sizing up to 55 millimeter. Apple maggot has been caught in the region and the next codling moth flight will be starting soon. 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 to 18 inches below visible damage and instruments should be sanitized between cuts. Here is some practical management information from Washington State Extension.
Blueberries: Blueberries in Fenton are starting to turn blue. Fungicides for anthracnose, Alternaria, and Botrytis should be included in your sprays in addition to sprays to protect against Spotted Wing Drosophila. 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. Most growers have started to harvest tart cherries. Many growers are taking steps to repel birds.
Grapes: We are getting close to berry touch in Fenton and Ray Township. 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 had enough smoke exposure to cause noticeable changes (usually noticeable when smokiness happens after veraison).
Strawberries: Some U-picks are still open, though many 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 just about at pit hardening. Peaches undergo a second round of growth from cell expansion at this stage. The earliest peaches in the region will be picked as early as this week.
Pears: European pear fruitlets continue to grow.
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, and the RimPro model indicates that 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. Models indicate that we are past the primary scab infection window.
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 to 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.
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.
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. We have seen our first catches in warmer parts of the region.
Cherry Fruit Fly: First caught June 18 in the region, but numbers have been low.
Codling Moth: Numbers seem to have dropped in response to cover sprays. We expect the next flight to begin soon.
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.
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: Some egg hatching has been reported in Southwest Michigan.
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 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 and are heavy in some places, particularly in orchards with larger canopy trees.
Seasonal weather update
The haze has cleared up and we have been having hot and wet conditions. We have potential for rain on Thursday, Saturday, and Tuesday and temperatures shouldn't go higher than the low 80s degrees Fahrenheit.
Despite recent wet weather (about 1.25 inches rain last week), 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 - July 5, 2023, issued July 5, 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)||10.1||201||12.2||212|
|Emmett (St. Clair)||12.6||239||10.4||230|
|Average of stations in this region:||9.9||196.8||11.1||206.4|
|Difference in Liquid Precipitation Accumulation from Mar. 1 observed June 26 and July 5, 2023; issued July 5, 2023|
|Station (County)||Rainfall Total (in.) June 26||Rainfall Total (in.) July 5||Difference from June 26-July 5||Hours with Rainfall June 26||Hours with Rainfall July 5||Difference from June 20-June 26|
|East Lansing MSU Hort (Ingham)||8.6||10.1||1.5||190||201||11.0|
|Emmett (St. Clair)||11.5||12.6||1.2||217||239||22.0|
|Average of stations in this region:||8.7||9.9||1.3||182.5||196.8||14.4|
The medium range guidance calls for normal to above-normal temperatures with normal to above-normal precipitation in July.
Our regional average growing degree day accumulation is fairly close to the 5-year average.
|Degree Day Accumulation Mar. 1 - July 5, 2023, Forecast from June 6-July 11, 2023; issued July 5, 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)||1668||1724||1843||1419||1474||1576||1056||1100||1183|
|Emmett (St. Clair)||1486||1570||1654||1244||1330||1394||897||978||1017|
|Average of stations in this region:||1613||1673||1788||1366||1429||1523||1006||1065||1133|
|Difference in Degree Day Accumulation from Mar. 1 observed June 26, and July 5, 2023; issued July 5, 2023|
|Station (County)||Degree Days Base 42 F June 26||Degree Days Base 42 F July 5||Degree Days Base 42 F Difference||Degree Days Base 45 F June 26||Degree Days Base 45 F July 5||Degree Days Base 45 F Difference||Degree Days Base 50 F June 26||Degree Days Base 50 F July 5||Degree Days Base 50 F Difference|
|East Lansing MSU Hort (Ingham)||1398||1668||270.0||1175||1419||244.0||857||1056||199.0|
|Emmett (St. Clair)||1238||1486||248.0||1023||1244||221.0||721||897||176.0|
|Average of stations in this region:||1346||1613||267||1125||1366||241||810||1006||196|
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.