East Michigan fruit update – July 30, 2019

Protection from spotted wing Drosophila infestation will need to continue to the end of harvest for tart cherries, summer red raspberries, fall raspberries and blueberries.


Rain from several thunderstorms that moved over the region in the last week has brought some much-needed drought relief for some growers. However, precipitation totals from these events have been extremely variable over short distances, ranging from just a few tenths of an inch to over 3 inches. Unfortunately, a few growers received hail during these thunderstorms. Some of these hail storms were severe, causing a good amount of fruit injury.

Our season has again moved forward with the heat of the last week to now being normal to four to eight days ahead of normal when looking at growing degree day (GDD) totals for most of the region. The tip of the Thumb is the only area of east Michigan that remains a few days behind normal. However, when I look at the start of harvest of our fruit crops being currently harvested, we are at least a week ahead of normal for the typical start of harvest dates.

East Michigan GDD totals for March 1 to July 29, 2019





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 growth has picked up again for growers that have received rain over the last few weeks; apples are mostly 2.25 to 2.75 inches in diameter. Harvest of Lodi and other transparent apples has taken place in the last week at most farms. Harvest of other summer apple varieties is quickly approaching. I estimate that Jersey Macs will be ready to harvest in seven to nine days. Hand thinning is just about wrapped up in apples.

I have no new apple pests to report this week. A few apple maggot continue to be caught in both yellow sticky traps and red ball traps this week; however, their numbers are generally low thus far this season. A few more woolly apple aphids are being found in hot spots in apple blocks and a few are moving out toward the terminals. Overall, I am not seeing high numbers of woolly apple aphids as I had expected based on very high populations in many blocks last fall.

Green apple aphid numbers continue to build in a few apple blocks. Japanese beetle adults continue to be seen, but generally their numbers are low for this time of the season. A few European red mite, twospotted spider mite and apple rust mite adults continue to be found. Late last week I started to see just a few scattered trees where leaves are starting to bronze from apple rust mites.

A few orchards are finding obliquebanded leafroller and redbanded leafroller larvae. Oriental fruit moth and obliquebanded leafroller trap catches are on the raise this week. Codling moth larvae feeding injury was seen for the first time last week and trap catch remains steady and low at most farms. Potato leafhopper adults are being found in many apple blocks. There are no new beneficials to report this week; lady beetles, six spotted thrips and green lacewing adults continue to be found.

Keep an eye on the sooty blotch and fly speck Enviroweather model as we are approaching 240 hours of wetting at many of our sites. Apple scab fruit lesions continue to be found in more blocks this week. Growers are asking why so much apple scab is showing up on the fruit with much less than normal showing up on the leaves. Powdery mildew infected terminals continue to be found in many apple blocks.

Pears have taken on a nice swell in the last week, they are mostly 1.75 to 2.25 inches in diameter. Pear psylla continue to be present in all stages.

Peach harvest has begun on a few early varieties. Split pit is an issue in some of these early varieties. Fruit have taken a good swell in the past two weeks; they are mostly 2 to 2.5 inches in diameter for the largest sized fruit. Many varieties are starting to color. A few green peach aphids continue to be found. I am also starting to see some oriental fruit moth feeding damage in fruit, especially were thinning was not adequate and peaches are touching each other.

Sweet cherry harvest is complete across the region. Many growers stopped harvest earlier than expected due to finding fruit infested with either cherry fruit fly or spotted wing Drosophila larvae, mostly in fruit growing in the top/middle of larger trees. This infestation was mostly a spray coverage issue.

Tart cherry harvest has wrapped up for many fruit farms. For some growers, the heat caused fruit to mature quickly and thus fruit quality was poor. For other growers, they stopped harvest earlier than expected due to finding fruit infested with either cherry fruit fly or spotted wing Drosophila larvae, mostly in fruit growing in the top/middle of larger trees. This infestation was mostly a spray coverage issue. Cherry fruit flies continue to be caught in traps. There are blocks with heavy leaf drop from cherry leafspot disease. Now that harvest is complete for most growers, fungicide applications are being made soon to slow the spread of this disease.

Plums are mostly 1 inch in diameter for European varieties, with much less fruit drop this week compared to a week earlier. Methley Japanese plums are close to being ready to harvest or are being harvested. Shiro Japanese plums are coloring well and are mostly 1.75 to 2 inches in diameter. Many Japanese varieties have a light crop this season.

Small fruits

Strawberry renovation is complete at most farms and where precipitation or irrigation has been adequate, regrowth has begun. Newly planted strawberries are runnering well. I continue to see several new plantings with severe leaf curling or cupping from potato leafhopper adult feeding.

Raspberry harvest continues for summer red raspberries, although it is quickly wrapping up due to heat that is causing berries to ripen quickly and diminish quality and size. Black raspberry harvest is complete. Many fall red raspberry growers are picking the bud berries or berries on the shorter interior growing canes. Harvest of this year’s crop of fall red raspberries will begin in earnest soon on early varieties, good numbers of fruit are staring to color. High trap catch of spotted wing Drosophila adult trap continues in all raspberry crops. A few summer red raspberry farms have stopped harvest due to finding berries infested with spotted wing Drosophila larvae. Control measures should have started over a week ago at most farms and will need to continue to the end of harvest.

Blueberry harvest continues this week. Most farms have a nice crop this season. Some varieties have put on a good amount of branch and leaf growth in the last month. High trap catch of spotted wing Drosophila adults continues in blueberries. Control measures should have started over a week ago at most farms and will need to continue to the end of harvest. A few canes are dying from Phomopsis canker.

Grapes are at berry touch this week. Grape berry moth larvae are being found feeding in grape clusters. Japanese beetles continue to be found in greater numbers this week. A few growers are seeing higher numbers of twospotted spider mites. Black rot symptoms are starting to be seen on berries. Powdery mildew symptoms continue to be seen on leaves. Another round of removing suckers from the base of canes is taking place in many varieties.

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