Southeast Michigan fruit regional report – June 25, 2013

Strawberry harvest is nearly finished in the southeast region and sweet cherry harvest is beginning.

Weather

Warmer temperatures and adequate soil moisture supplies pushed growth ahead, resulting in a spurt of growth for most of our fruit crops in the last week. Our season is running back toward normal again in terms of growth stages, growing degree day (GDD) totals and the start of harvest of our fruit crops.

Reports of scattered hail were reported at farms in Monroe and Lenawee counties from strong thunderstorms that quickly moved through the region on Saturday, June 22. Rainfall totals varied greatly across the region in the last week, from a low of a few hundreds to an inch to 1.3 inches. Soil moisture is more than adequate at most farms.

East Michigan growing degree day totals for March 1 to June 24

Location

GDD42

GDD45

GDD50

Commerce (Oakland)

1281

1081

781

Emmett (St Clair)

1260

1062

767

Flint (Genesee)

1428

1219

907

Lapeer (Lapeer)

1301

1103

806

Petersburg (Monroe)

1447

1232

909

Pigeon (Huron)

1208

1017

734

Romeo (Macomb)

1304

1104

799

Tree fruits

Apples are 1.5 inches in the south and 1.25 inches in the Flint, Mich., area. June drop is starting to be seen at most farms, and fruit drop from thinning continues to be seen. Even larger fruit are dropping. More and more apples are showing up as time goes on. Almost all apple growers will need to do a fair amount of hand-thinning this season, as thinners did not do the entire thinning job in most apple blocks. Honeycrisp leaves continue to show their typical leaf modeling symptoms.

Two-spotted spider mites are starting to be seen in apples in the last few days. San Jose scale crawlers are being seen at more farms this week. Potato leafhopper adults are being seen at more farms this week, especially on younger trees. Green apple aphid populations continue to be high in many blocks, with some blocks starting to see some honeydew. Rosy apple aphid leaf curling remains, however the pest has been controlled well this season by predators in most apple blocks. Wooly apple aphids are moving from the tree trunks to the terminal branches. Codling moth and oriental fruit moth trap catches remain low. Trap catches have remained low again this week. Plum curculio populations have remained very low this season in most of the region, with little fruit “stinging” on any tree fruit this season. Mullein bugs continue to be found in apples – they are now predators. There continues to be high numbers of predators being seen this season.

Early last week I caught just a few apple scab spores at both of our spore trapping stations during wetting events and thus I affirmed that we are at the end of primary apple scab season. I can find just a touch of apple scab leaf infection at most apple farms, and I’ve seen fruit scab at a handful of farms in the last week. I have not seen any new fire blight strikes in the last week. I continue to see twig infections of powdery mildew, mainly on susceptible varieties.

Pears are 1.5 inches at most farms where growers who have a crop. All stages of pear psylla are now present.

Peaches are now 1.25 inches. Peaches fall into two groups this season. Most have an abundant crop and others have no crop at all. The foliage in these blocks with no crop had been yellowing and stunted thus far this season, however it looks much more like normal in the last few weeks. Bacterial spot infection on the leaves continues to be found at many farms.

Sweet cherry harvest has just started in the last few days at many farms. Fruit size is a problem at most farms. One of my astute fruit growers noted that the fruit stems on many of the cherries, particularly in the lower part of the tree, are a pale yellow color and are not the normal size and color. I have seen this at many farms this week as well. Perhaps these stems were damaged from frost and are contributing to poor size. Birds are continuing to feed in most sweet cherry blocks. Cherry leaf spot disease symptoms are seen in many blocks.

Tart cherries are at 18 to 20 millimeters in size. Tart cherries continue to color, and I have the same concerns about poor fruit size for tarts that I do for sweet cherries. I have heard the term “pits and stems” more than once in the last few days. Cherry leaf spot disease symptoms are seen in most tart cherry blocks, and in the last week yellowing leaves have developed and are starting to drop to the orchard floor.

Plums are 1 inch for both European and Japanese types. Aphid populations are continuing to grow.

Small fruits

Strawberry harvest is in full swing. Warmer temperatures have pushed ahead ripening. Farms in the south are hoping to have enough berries to stay open through the end of the week, and growers in the Flint, Mich., area are thinking they will be ready for harvest into early next week. Growers need to start thinking about renovation. Potato leaf hopper feeding and leaf curling is being seen in most new plantings. Newly planted berries are runnering well.

Raspberries are at 30 inches of new growth for summer-bearing types, with red fruit being seen in early varieties. Canes of fall-bearing types are about 30 to 36 inches tall. According to Michigan State University Extension, spotted wing Drosophila traps need to be set in summer raspberries at this time in order to detect first catch of adults.

Blueberries are 14 to 16 millimeters for Blueray and Bluecrop and 10 millimeters for Jersey and have not sized much in the last week. Spotted wing Drosophila traps need to be set in blueberries at this time in order to detect first catch of adults.

Grape cane growth continues at a rapid pace, with new canes having 48 inches of growth. Concord types are at buck shot in size and French hybrid types are at petal fall. Grape berry moths have been very active in wild grape vines.

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