Southeast Michigan fruit regional report – June 9, 2015

Strawberry harvest begins in southern counties, others to follow later this week. Primary apple scab season continues.


With widely varying amounts of rain over the last two weeks, most fruit growers report their soil moisture levels are working their way back to normal. Rainfall totals for the last two weeks vary greatly across east Michigan, ranging from 1.1 to 4.1 inches. However, growers need to keep an eye on their subsoil moisture levels as most are still dry and need more moisture.

For most of east Michigan our season is running about normal for growing degree day (GDD) totals as well as growth stages, with the exception for strawberries which remain several days behind normal. Widely scattered reports of pea-sized hail have been reported by a few apple growers, some from thunderstorms Thursday, May 28, and others this past Sunday, June 7. While damage to fruit can be found, it was not extensive.

East Michigan GDD totals from March 1 to June 8, 2015





Commerce (Oakland)




Emmett (St Clair)




Flint (Genesee)




Lapeer (Lapeer)




Petersburg (Monroe)




Pigeon (Huron)




Romeo (Macomb)




Tree fruits

Apples are mostly 1-1.25 inches and have sized well in the last week due to good rains at most farms. June drop is just starting for some growers and is in full swing for others. Apple crop load remains mixed and extremely variable across the region this season, some growers are waiting to see if their last thinner application is going to remove more fruit. While it is early in the season to accurately assess crop load, I think in the end there will be more apples than growers currently think they have. Most blocks will require some hand-thinning to even out the crop variability from tree to tree and in the tops of trees.

Most apple blocks have put on a good amount of new leaf and twig growth in the last week. The exception is apple blocks where leafs were heavily eaten by leafrollers after bloom. Summer application of NAA to encourage flower bud formations for next year’s crop are approaching for apple growers; these should be applied five, seven and nine weeks post-bloom. Additional details can be found in the Michigan State University Extension article, “Use summer NAA to enhance return bloom on apple varieties.”

Unfortunately, apple scab lesions continue to show up in light amounts in many apple blocks, mostly on leaves and this week on more fruit. The number of spores released in wetting or rain on Sunday, June 7, continues to decline, but I did catch spores and we are still in primary apple scab season. According to the MSU Enviro-weather apple scab maturity model, we were at 100 percent of spores being mature May 25-28. However, once spores mature they still need two to four wetting events to be released.

More widely scattered fire blight strikes are being seen in apple blocks. I have heard several growers report in the last few days they have never seen this much fire blight in there orchard. I have seen a few newly planted or young apple blocks where there has been as high as 15 to 20 percent tree mortality from fire blight. I have not found any oozing from last season’s cankers. Growers need to inspect fire blight-sensitive varieties closely for infections and remove infected limbs or trees as soon as possible.

Powdery mildew-infected twigs are starting to be seen in a few apple blocks. The leaf stage of black rot, known as frogeye leaf spot, is starting to be found in a few apple blocks. I continue to see orange leaf spots from cedar apple rust in a few apple blocks.

Codling moth trap catches continue to decline for first generation flight. Many growers biofixed for codling moth May 19 or 20 and in the last few days have applied cover sprays for codling moth egg hatch. Spotted tentiform leafminer mines from first generation adult flight are starting to be found. A few colonies of rosy apple aphids continue to be found on interior twigs. A few green apple aphids and apple grain aphids are being seen. Predators or beneficials seem to be doing a good job of controlling all three aphid pests. A few potato leafhopper adults continue to be seen, as well as tarnished plant bugs. Oystershell scale crawlers are starting to wax over. San Jose scale adult males continue to be caught in traps in high numbers; no crawlers are being found. Most of the blocks that had high populations of leafrollers a few weeks ago now have them under control. European red mite egg hatch continues, as well as a few rust mites. Good numbers of beneficial insects continue to be found in many apple blocks.

Lastly, there is some scaring on apple skins that do not appear to be from diseases or insects. I believe most of this surface browning is from cold injury on one of our frosty nights/mornings, most likely the morning of Saturday, May 23. Other apples have frost rings on fruit.

Pears are mostly 20 to 23 millimeters in size, much of the side bloom is starting to drop. All stages of pear psylla continue to be seen this week.

Peach are 1 inch for those few growers with a crop this season. There is a fair amount of oozing on trunks and scaffold limbs from winter injury. Growers continue to remove dead and dying trees; most of these blocks are older. Green peach aphids are being found in a few blocks. Tarnished plant bugs continue to be seen this week.

Sweet cherries are 13 to 15 millimeters in size, about the same size as last week. Most varieties continue to see straw-colored fruit with some starting to have a few red fruit. This straw- and red-colored fruit may be prone to drop early – I hope not as most farms have a light crop of sweets. Cherry leaf spot-infected leaves are starting to be found in just a few blocks. Now is a time to control it as new leaves continue to emerge.

Tart cherry are at 10 to 12 millimeters in size, again about the same size as last week. Cherry leaf spot needs to be controlled at this time.

European plums are 16 to 18 millimeters and Japanese plums 8 to 20 millimeters. Some Japanese plum varieties have little to no crop this season.

Small fruits

Grape shoots for Concord types have extended quickly again this past week with many being 36 inches in length. Flower buds continue to elongate. Bloom is expected later this week. Many European varieties have extensive winter kill and growers have either pruned them back to just above the bud or pulled them out entirely.

Strawberry harvest is just getting started for farms in the south. Many other farms south of Flint and Port Huron, Michigan, open for first harvest later in the week. The start of strawberry harvest will be several days later than normal. Tarnished plant bugs continue to be found at a few farms. Leaf spot disease is more common this season compared to most seasons, mostly on older of first of the season leaves.

Raspberries are at small green fruit for early flowering summer varieties. Dead cane tips continue to be seen in several varieties of summer fruiting raspberries. These dead cane tips should be pruned at this time. Fall red raspberry canes continue to put on good new growth, with the longest canes being 30 to 36 inches in length.

Blueberries have small green fruit, the largest are 14 millimeters in size. Some varieties have had poor leaf growth this spring, such as Bluecrop. New growth and leaves are starting to look better this season on these varieties.

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