East Michigan fruit update – June 18, 2019

Strawberry harvest is finally underway across the region. Many fruit growers received another inch or two of precipitation in the last week.

Weather

Wet soils continue to be a major challenge for fruit growers across east Michigan. The never-ending precipitation cycle brought more rain to most of the region over the last week. Most fruit farms saw 1.2 to 2.0 inches of precipitation over spread over the last week, with many of our Michigan State University Enviroweather stations across the region receiving measurable precipitation in four to five of the last seven days. This was the fifth to sixth week in a row for growers receiving measurable rainfall over so many days.

Our season remains cool as well. We are still running between four to seven days behind normal when looking at both flowering stages and growing degree day totals for region, even with warmer daytime temperatures.

A few farms are reporting hail in the last week.

East Michigan growing degree day totals for March 1 to June 17, 2019

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

987

793

520

Deerfield (Monroe County)

1144

929

629

Emmett (St Clair County)

737

564

328

Flint (Genesee County)

1054

856

570

Freeland (Saginaw County)

947

764

498

Lapeer (Lapeer County)

961

773

508

Pigeon (Huron County)

792

619

381

Romeo (Macomb County)

1018

822

544

Tree fruits

Apples in the mid-parts of our region (Ann Arbor through Flint) are mostly 24 to 32 millimeters in size. With all of the precipitation we have received this season, apple size is very large compared to most seasons. The tail end of June drop is taking place in a few apple varieties. Many apple blocks will require some hand thinning, which can begin at any time. Overall, most growers have a good fruit set at this time.

New or terminal growth of branches and leaves has continued to be rapid over the past month. Some leaves this season are very large and oddly shaped, with some having lobes on them. Some newly planted trees still have bloom on them.

Insect pest pressure in apples has mostly leveled off this week. The only new insect development is the start of trap catch for obliquebanded leafroller adults. Obliquebanded leafroller larvae were first seen in late April and early May. Codling moth trap counts have generally leveled off this week, with most traps catching numbers below the threshold of five moths per trap. Most growers biofixed two weeks ago. If I had to set a regional biofix date, it would be May 31.

White apple leafhopper adults and trap catch of brown marmorated skink bug adults continue to be found. A few more tarnished plant bug adults and this week more nymphs are being seen, along with some fruit damage. I am seeing more plum curculio damage or stings this week in apples and other tree fruit crops. I continue to see a few green apple aphids and potato leafhopper adults. Again this week I expected to find the first signs of woolly apple aphids, but I have not found any yet. A few blocks of apples have spotted tentiform leaf miner larva in the leaves. A few green lacewing adults and eggs are the only beneficial I have found this season.

Silver leaf symptoms are showing up in a few apple varieties this season, some in blocks that have never shown symptoms. I think the wet soils are causing more of this disease to show up this season. This is the only new disease to report this week. A few fire blight shoot strikes continue to be found. More streptomycin leaf yellowing or burn continues to show up on more sensitive varieties. Apple scab lesions on fruit continue to be found, but at low levels. Powdery mildew infected terminals continue to be found in more apple blocks. More signs of cedar apple rust symptoms continue to be found on leaves. Oddly, I am not finding any galls on nearby cedar trees.

Pears are 21 to 24 millimeters in size. Pear psylla adult flight continues.

Peaches are mostly 18 to 24 millimeters in diameter for the largest sized fruit. Hand thinning has begun in peaches. A few green peach aphids continue to be found. Peach leaf curl symptoms are very common this season in many blocks.

Sweet cherries are starting to put on a flush in size and are starting to color, they are mostly 14 to 16 millimeters in size for the largest fruits. Fruit drop is continuing in sweet cherries this week. Most growers had a great crop of sweets as of a few weeks ago; with the fruit drop, they still have an OK to good crop coming along. There are early some signs of cherry leafspot disease showing up on leaves at a few farms.

Tart cherries remain mostly at 11 to 13 millimeters in size for the largest fruits, with some drop occurring in tarts as well. Some coloring is starting to be seen in tarts as well.

Plums are 15 to 19 millimeters in diameter for European varieties and 18 to 22 millimeters in diameter for Japanese varieties t. Many Japanese varieties have a light crop this season.

Apricots are mostly 32 to 35 millimeters in size.

Small fruits

Strawberry harvest for early varieties began late last week at most farms. Mid-season varieties will begin harvest soon as well. Berry size has been excellent this season. I am glad to see the cooler weather continue, as it will help preserve berry quality. The only new pest in strawberries this week are a few reports of angular leaf spot symptoms—scout soon for this disease. Scout closely for slugs due to wet soils this season.

Raspberry canes continue to elongate in both summer and fall raspberries; most summer raspberries have small fruitlets that are continuing to size, with no coloring yet. Fall bearing blackberries have been very slow to emerge from the ground this season. Some of this might be due to winter injury. I had the first of the season trap catch of spotted wing Drosophila adults in traps two weeks ago, but did not have any catch this week.

Blueberries mostly have fruitlets around 9 to 11 millimeters in size. Bloom has ended. I had the first of the season trap catch of spotted wing Drosophila adults in traps two weeks ago, with none were caught this week, although it is too early to have fruit damage in blueberries.

Saskatoons are 8 to 9 millimeters in size with a nice crop coming along this season. Fruit are beginning to color.

Grapes are at prebloom, most have 24 to 30 inches of new growth. Some mildew signs are starting to show up. Wild grapes are beginning to flower.

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