East Michigan fruit update – June 30, 2020

Strawberry harvest has finished at most farms. Summer red raspberry, sweet cherry and saskatoon harvest is getting started. A few areas received good precipitation last weekend, but drought conditions continue in most areas.

Saskatoons
Saskatoon harvest begins. Photo by Bob Tritten, MSU Extension.

Weather

Precipitation totals from rain on Friday evening, June 26, and Saturday morning of last week varied widely across the region. Rainfall totals ranged from 0.0 to 1.44 inches. Overall, soils over much of the region have continued to dry out. Signs of drought stress are being seen more commonly this week than last week, especially in newly planted tree and small fruit crops, in shallow rooted fruit crops, and this week in younger plantings that are a few years old. Sod in most orchards has turned brown, and lanes and driveways are very dusty.

As a result of another week of warm temperatures, we saw another good increase in growing degree day (GDD) accumulations. Most of our Michigan State University Enviroweather stations have seen a rise of 130 GDD base 50 accumulations in the last week.

Our season is still hovering a few days ahead to a few days behind normal for both growth stages and GDD.

East Michigan growing degree day (GDD) totals for March 1 to June 29, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

1424

1196

865

Deerfield (Monroe County)

1580

1333

980

Emmett (St Clair County)

1390

1163

841

Flint (Genesee County)

1545

1306

957

Freeland (Saginaw County)

1383

1156

832

Lapeer (Lapeer County)

1414

1185

854

Pigeon (Huron County)

1319

1104

803

Romeo (Macomb County)

1444

1212

877

Tree Fruits

Apples have continued to size well over the last week, despite dry soils. Most apple fruit are now 1.375 to 1.5 inches in diameter. Most apple varieties have between 22 and 24 inches of new terminal growth. The lingering, long and steady June drop has just about ended, but I am still finding a few small freshly dropped fruitlets on the orchard floor in many varieties. Hand thinning has not started yet in apples but will be needed in many apple varieties.

I have two new insect pests to report in apples this week. Apple maggot trap catch started in the region yesterday, June 29. Low numbers of adults have been caught on both yellow sticky boards and red ball traps. Apple rust mites are the second new pest to report this week. While numbers are still low, they will bear watching in this hot weather. Potato leafhoppers numbers have risen dramatically at some farms in the last week, with a good amount of leaf curling. Two weeks ago week I reported San Jose scale adult male trap catch and last week found some crawlers. This week I am just starting to see a few crawlers waxing over, meaning that the crawler control window is beginning to close.

Trap catch of obliquebanded leafroller adults is dropping off. European red mite and twospotted spider mites continue to be found in higher numbers, but neither are at threshold levels yet. A few white apple leafhopper adults continue to be found feeding on leaves, as well as a few woolly apple aphids around pruning scares. I continue to see a few codling moth larvae in apples. Trap counts of adults are generally low at this time. Beneficial or predator numbers continue to build. This week I am finding minute pirate bugs, red velvet mites, lady beetles and lacewing adults.

I am seeing entire limbs that are wilting and browning from black rot infections in the wood tissue. I have no new reports of growers finding fire blight strikes. A number of growers are finding cedar apple rust symptoms on fruit, more than they have seen in years. Apple scab fruit lesions continue to be found. Some apple blocks continue to have high numbers of powdery mildew infected terminals on mildew prone varieties. Protection programs need to be ongoing on mildew prone varieties.

Leaf mottling has started to be found on Honeycrisp leaves. The mottling is caused by the accumulation of large starch granules in the leaves that reduce photosynthesis.

Pears are mostly 1.25 to 1.5 inches in diameter. Pear psylla adult numbers continue to slowly rise as suckers continue to elongate. Sucker removal is beginning in pear blocks.

Peaches are between 1.25 and 1.375 inches in diameter. Pit hardening is just beginning. Thinning continues in some blocks; others will not require thinning due to frost damage. Green peach aphids continue to be found in many peach blocks. I have not seen any flagging from oriental fruit moth in peaches but expect to find some soon. Peach leaf curl symptoms are common across the region, but as new leaves develop, the symptoms appear to be diminished.

Sweet cherry harvest started at a few farms in the last few days, others will begin harvest later this week. Unfortunately, harvest has quickly wrapped up at most farms due to the short crop. Leaf spot symptoms are a new pest to report in sweet cherries this week; control programs need to be maintained. A good amount of bird damage is being found in the remaining fruit, mostly from cedar waxwings and robins.

Due to the short crop, most growers do not need to be concerned about spotted wing Drosophila (SWD) control in sweet cherries. SWD trap catch started to be seen in all traps across the region two weeks, it rose by just a few last week, and this week the number found in traps have only slightly climbed.

Tart cherries have colored well in the past week. They are mostly 16 to 18 millimeters in diameter. As is the case in sweet cherries, I have seen a good amount fruit drop in tarts over the last six weeks. Most blocks only have 5 to 10% of a crop remaining, but a few may have 30 to 40% of a crop. Many growers report they don’t have enough of a tart crop to even pick. Leaf spot control programs need to be maintained as cherry leaf spot symptoms are starting to be seen.

For growers with a crop of tart cherries to harvest, you need to be concerned with spotted wing Drosophila (SWD) control. SWD trap catch started in all traps across the region two weeks ago, but their numbers have been fairly low since then. With the start of harvest for some blocks of tart cherries approaching, protection programs will need to start soon to control it.

Plums are approaching an inch in diameter for European varieties, with Japanese varieties at 1.375 inches. As is the case for both sweet and tart cherries, most plum blocks have a poor crop due to freeze/frost damage.

Small fruits

Strawberry harvest has wrapped up in the last few days at farms to the south of Flint, Michigan, with others to follow later this week. Demand for both ready picked and pick your own strawberries was very strong this year. Leaves on newly planted strawberries continue to emerge from the crown, along with flower trusses and runners. Deflowering is taking place. Renovation is beginning at many farms this week. Growers with dry soils may need to get their irrigation systems back into strawberry fields fairly quickly to begin irrigation as renovation is wrapped up.

Raspberry harvest is underway for early maturing summer red raspberries. Later maturing varieties are coloring well and will begin harvest soon. Berry size is small where soils have been dry over the last month. Growth has continued to be good on fall bearing raspberries that have been irrigated, the tallest canes are 30 inches in length. Flower buds are starting to be seen on the bud berry canes or shorter fall red raspberry canes.

Some light amounts of raspberry cane borer and raspberry sawfly larvae feeding damage is being found at just a few farms. Spotted wing Drosophila (SWD) trap catch started to be seen in all traps across the region two weeks ago and continued to be seen in low numbers through this week. With the start of harvest for summer red raspberries, protection programs need to be underway.

Blueberries are continuing to color well; berry size is mostly between 8 to 12 millimeters in diameter. Blueberry maggot trap catch has been seen in southwest Michigan, but none over here on this side of the state yet. I expect to see trap catch soon.

Grape growth has moved quickly again this week, with concords at BB sized fruit. Vinifera varieties at petal fall. Many new canes are 48 inches in length. Japanese beetle adults were found in grape late last week. Their number are low but they are on their way. Grape berry moth populations are very high in southwest Michigan, but I have not seen feeding damage or webbing.

Saskatoon harvest began over the weekend. Remaining fruit are continuing to size and color well. Most fruit are between 11 and 13 millimeters in diameter. Heavy bird feeding continues in saskatoons, mostly from cedar waxwings and robins.

Haskap harvest is underway. Unfortunately, most of the fruit has been consumed by bird feeding over the last few weeks.

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