East Michigan fruit update – Sept. 4, 2018

Most areas received ample rains over the last two weeks, bringing seasonal totals back to normal to above normal levels. Drought continues for a few growers, mainly in the southern reaches of the region.


The average precipitation total for the last two weeks for the eight Michigan State University Enviroweather stations listed in the following table was 2.7 inches. The seasonal trend of great variability of precipitation over the region continues over the last two weeks, with the range being as low 0.55 inch at Deerfield to a high of 4.53 inches for Freeland.

Prior to these recent rains, most areas of the region were running 2 to 4 inches below normal rainfall for the season. Now, most growers are back to normal to above normal for seasonal rainfall totals.

There are still some isolated pockets of the region that have not had good rainfall events since early to mid-June. These areas are mainly to the south. So for these growers, the drought continues.

Our season continues to be 14 days ahead of normal in degree-day totals and about five days ahead of normal in terms of the start of harvest for summer fruit crops. However, some early fall apple and most peach varieties are starting harvest just a few days ahead of their normal harvest dates. Degree-day totals have continued to build rapidly with hot day time temperatures and warm morning lows.

East Michigan GDD totals for March 1 to Sept. 3, 2018





Commerce (Oakland County)




Deerfield (Monroe County)




Emmett (St Clair County)




Flint (Genesee County)




Freeland (Saginaw County)




Lapeer (Lapeer County)




Pigeon (Huron County)




Romeo (Macomb County)




Tree fruits

Apple harvest is quickly approaching for the first of our traditional fall apple varieties: Gala, Honeycrisp and McIntosh. Growers have been busy staging bin piles and even begun setting some bins in the orchard row. SweeTango harvest is complete. I expect to see harvest of Gala and Honeycrisp to begin over the next week. A few growers on early sites are spot-picking just a few Honeycrisp, Gala and even some early maturing McIntosh strains. This early harvest is mainly on young trees with a light crop.

Fruit color is not good at this time. Growers are hoping for cooler temperatures to improve color. Fruit size is smaller than expected at most farms, except for growers that have been irrigating on a regular basis and for the few fortunate growers that have not been experiencing drought conditions over most of summer. Application of harvest management aids have continued on several varieties.

With the exception of codling moth at some farms, woolly apple aphids and brown marmorated stink bugs, most apple insect pest populations have been declining over the past two weeks. This includes apple maggot, European red mites, twospotted spider mites and San Jose scale crawlers.

Light to moderate amounts of codling moth feeding damage is being found at several farms, even on farms that have been using mating disruption. Trap counts are still high at a few farms that have had high codling moth pressure for the entire season. Another cover may be needed in these high-pressure blocks.

Brown marmorated stink bug (BMSB) trap catch continues to rise slowly but steadily at most trapping locations, both adults and young nymphs are being caught in traps. Over the last few weeks, growers have continued to find some limited BMSB feeding damage on fruit as it is being sorted or graded. It has been very hard to find this damage in the orchard prior to harvest. Most of this feeding damage is three to four weeks old.

Woolly apple aphid numbers on young terminals have risen sharply in a few isolated locations in a few apple blocks.

I continue to find reduced numbers of predators, as their food supplies are declining. I am still finding lacewing adults, lady bug adults and minute pirate bugs.

Sooty blotch and flyspeck are pests I first reported a few weeks ago; more growers are finding it on fruit since the recent rain events. I am concerned about these pests for growers that have had heavy rainfall over the past few weeks. Track wetting hours on the Enviroweather sooty blotch/flyspeck model. Another fungicide cover may be needed to control it on later season varieties.

Black rot symptoms on fruit are being on several varieties at some farms, mostly on Honeycrisp. A few more “waves” of leaf yellowing and drop have been seen on Golden Delicious and related strains from necrotic leaf blotch. Many unsprayed apple and crabapple trees are experiencing extensive leaf yellowing and drop caused by apple scab. Watching these trees can give you an idea of pest pressure for next season, and even the possibility of pin head scab developing in stored fruit this fall.

Pear harvest is mostly complete for Bartlett and related varieties. Other winter varieties need more time to mature.

Peach harvest is nearing an end for late season varieties. Light amounts of brown marmorated stink bug (BMSB) feeding damage has been seen at many farms, mostly as fruit was being graded. The fruit damage was hard to find in the orchard. If you find suspected BMSB feeding damage or adults in peaches, I would like to hear from you (contact me at tritten@msu.edu or 810-244-8555).

I have had several reports of late season peach varieties having light amounts of bacterial spot infection on the fruit causing spotting.

Sweet cherry and tart cherry growers have continued seeing leaf yellowing, cupping and drop, which has been found mostly where soils have been dry. Most of this leaf damage was caused by a combination of drought stress and cherry leaf spot disease.

Plum harvest is wrapping up for European and Japanese varieties; most varieties had a short crop. Some blocks continue to have light amounts of bacterial spot infection on the fruit causing spotting.

Small fruits

Strawberries continue to look better and better for growers who have received good rainfall over the last three weeks. The rows in renovated fields are filling in nicely. New plantings continue to runner well on farms where soil moisture has been adequate, with the rows filling in nicely here as well. Some new plantings continue to have high populations of potato leafhopper.

An herbicide application window is open here in early September for weed control through the fall. Some hard to control weeds are growing well in renovated berries, especially yellow woodsorrel, white cockle, butter and eggs and wild carrot.

Raspberry harvest continues on fall bearing red raspberries. Blackberry harvest has begun over the last week or so. Now that most farms have had good precipitation over the last three weeks, production has once again ramped up to more normal levels.

Spotted wing Drosophila (SWD) populations continue to build in fall raspberries and will continue to rise throughout the fall. Be watchful that covers for control for SWD are being made on a five-to-seven-day basis, and more often after rain events.

Blueberry harvest has wrapped up on late season varieties.

Saskatoon leaves on unsprayed plants have continued to drop due to post-harvest feeding damage from apple skeletonizers.

Grape veraison is in full swing, with harvest of Concord types expected in the next week or so. Downy mildew has taken off again on several grape varieties.

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