East Michigan fruit update – July 10, 2018

We have had unusually high apple maggot trap catch in the last week. Dry soils are common across the region, causing wilting in all fruit crops.

July 10, 2018 - Author: Robert Tritten

Weather

Our growing degree-day (GDD) totals have continued to quickly build due to many hot days of the past week and more importantly warm nighttime temperatures. Our season is running 10 to 14 days ahead of normal in GDD totals and about five days ahead of normal in terms of the start of harvest of our fruit crops.

Dry soils over an increasingly larger part of east Michigan are the real story over the past two weeks. Rainfall totals have been extremely variable over short differences. Wilting of newly planted tree and small fruit crops is much more common this week. Yesterday, July 9, I noted some 3- and 4-year-old peach trees beginning to show signs of drought stress. Increasingly, growers are spending more time and energy focusing on irrigation. Keep a close eye on soil moisture supplies for signs of drought stress.

East Michigan GDD totals for March 1 to July 9, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

1878

1640

1262

Deerfield (Monroe County)

2045

1792

1399

Emmett (St Clair County)

1769

1536

1173

Flint (Genesee County)

1992

1748

1364

Freeland (Saginaw County)

1834

1595

1222

Lapeer (Lapeer County)

1832

1596

1227

Pigeon (Huron County)

1701

1474

1121

Romeo (Macomb County)

1919

1681

1307


Tree fruits

Apples have continued to size, but growth has slowed in the past week, most likely due to dry soils at many farms. Apples are mostly in the range of 1.75 to nearly 2 inches in diameter. Most growers have continued hand-thinning this week. The list of which varieties need hand-thinning is quite variable from farm to farm. Most growers need to thin Honeycrisp to help insure good fruit set for next year’s crop. Leaf yellowing or mottling continues to be more prevalent in Honeycrisp.

While there are no new pests to report in apples this week, several farms have seen a huge trap catch of apple maggot on red sticky traps in the last few days. With most of our soils being dry, this high apple maggot trap catch is surprising to me. Green apple aphid populations continue to be very high in many blocks, and this week a few blocks are seeing honeydew residue on apples from this pest. This honeydew can lead to more sooty mold later in the season. Brown marmorated stink bugs are being found in low numbers in traps at several farms this week. Feeding damage to fruit was seen about this time last season and has been found in other parts of the state in the last week.

European red mite and twospotted spider mite numbers have been building quickly, with some bronzing occurring on leaves mostly in the interior of isolated trees. A few blocks are now above threshold levels. Do a good job of scouting for them. Woolly apple aphids are continuing to move to terminal branches, which is early for them to be moving out to terminals.

Japanese beetle populations continue to build in most apple blocks. San Jose scale crawler activity has stopped at most farms. Apple rust mite numbers continue to build, but are generally lower than threshold numbers. Obliquebanded leafroller feeding injury on terminals and fruit continues to be found. White apple leafhopper and potato leafhopper adults are being seen for the fifth week on apple leaves in just a few apple blocks. Codling moth crawlers are being found in a few blocks. Rosy apple aphids continue to be found in a few blocks, causing leaf curling. On the beneficial side, good numbers of green lace wing adults and eggs are being found for the second week.

Sooty blotch and fly speck symptoms are expected to be seen fairly quickly in east Michigan. Many growers have or will be applying a fungicide to control it. More powdery mildew terminal branch strikes continue to be found this week. Cedar apple rust leaf symptoms continue be found this week. I continue to find and get reports from apple growers that just a touch of fire blight is being seen in many apple blocks. Nectria twig blight continues to be found in light amounts.

Pears have put on a good amount of growth this past week, with most being 1.5 to 2 inches in diameter. A few pear blocks are starting to see pear rust mites. Pear psylla populations have continued to build in blocks where control measures have not taken place and where suckers have good growth. Removing suckers will help with pear psylla control.

Peaches have put on a spurt of fruit growth in the past week, they are mostly 1.375 to 1.625 inches in diameter. Harvest of the earliest peach varieties began this week. Red Haven harvest is expected to begin in early August. European red mite numbers have been building quickly in some peach blocks, occurring on leaves mostly in the interior of isolated trees. More growers have reported finding brown marmorated stink bug nymphs feeding on young peach fruit. Be on the lookout for brown marmorated stink bugs in peaches.

Sweet cherry harvest will be wrapping in the next few days at most farms. For growers who are going to be harvesting longer, watch for cherry fruit fly and spotted wing Drosophila (SWD) trap catches. SWD flight has started in the region, but trap catch continues to be limited to a few flies. However, other parts of the state are seeing a big jump in trap catch. Even though trap catch is limited at this time, check traps every few days to determine when SWD start their flight at your farm. When they start being caught in traps, control measures need to start shortly thereafter.

Tart cherry harvest continues but is winding down at most farms. As was covered in the sweet cherry section, watch closely for the first SWD trap catch and begin to control it soon thereafter that catch.

Plums are about the same size as last week, with European varieties being just under 1inch in diameter and 1.5 inches for Japanese varieties. Some European and Japanese varieties have a very light crop on them.

Small fruits

Strawberry renovation continues at most farms. A few farms with late-season varieties have continued with harvest. Some growers are considering delaying the beginning of the renovation process until we get some good rains. Make sure berries are watered well following renovation. Many new plantings need some attention to weed control. Where flower buds have been removed, there is a good amount of runnering taking place in new plantings. Potato leafhopper feeding damage continues in a few newly planted berry fields.

Raspberry harvest continues in summer red raspberries and black raspberries, and a few fall raspberries are being harvested from the short bud berry canes growing in the row. Berry size is on the small size this season. Growth has slowed on new summer and fall bearing raspberries canes.

SWD flight has started in the region, but trap catch continues to be limited to a few flies. However, other parts of the state are seeing a big jump in trap catch. Even though trap catch is limited at this time, check traps every few days to determine when SWD start their flight at your farm. When they start being caught in traps, start control measures shortly thereafter.

I am seeing some potato leafhopper feeding damage to new canes or primocanes in summer and fall raspberries. A few bramble plantings have been hit hard with raspberry sawfly feeding damage.

Blueberry harvest is starting for early varieties with mid-season varieties to follow fairly quickly. Berries have sized well over the past week.

The first trap catch of blueberry maggot was seen early this week at a few farms. Look out for trap catches at your farm. Trap catch of its close relative, the apple maggot, was very high at several farms this week. SWD flight has started in the region, but trap catch continues to be limited to a few flies. However, other parts of the state are seeing a big jump in trap catch. Even though trap catch is limited at this time, check traps every few days to determine when SWD start their flight at your farm. When they start being caught in traps, start control measures shortly thereafter.

Saskatoon harvest continues for the latest varieties and will most likely wrap up late this week. Fruit size remains good. Unsprayed saskatoons are starting to show leafminer injury to the leaves.

Grapes continue to put on a good growth, with Concord types at berry touch and Vinifera types approaching berry touch. Japanese beetle populations continue to build; they were seen early this season and are now clustered up in groups of twos and fours. Powdery mildew continues to be seen on leaves and twospotted spider mite populations continue to build slowly.

Tags: east michigan fruit, fruit update, msu extension


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