East Michigan fruit regional report – May 24, 2016

Fire blight is still a concern for apple growers for the rest of the week. We had three frost events in the past week, but no flower bud damage is expected.

Weather

We had three frost events in the past week, with temperatures in the lower 30s on Wednesday, May 18, Thursday and Monday mornings. Most strawberry growers frost-protected at least two times and frost fans were running at many farms during these frost events.

Our season has dropped back to being slightly behind normal in terms of fruit crop growth stages and degree-day totals. Based on the 10-day forecast, it appears we will move ahead rapidly over this time period.

Most of our region has had no rain over the past week. Our soils generally have adequate to good moisture supplies at this time.

East Michigan growing degree-day totals for March 1 to May 23, 2016

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

553

416

244

Deerfield (Monroe County)

692

530

312

Emmett (St Clair County)

511

386

228

Flint (Genesee County)

617

477

294

Freeland (Saginaw County)

510

390

235

Lapeer (Lapeer County)

552

426

266

Pigeon (Huron County)

406

301

172

Romeo (Macomb County)

567

430

256

Tree fruits

Apples are mostly at petal fall for growers south of the I-69 corridor and full bloom to the north, with the exception of growers close to Lakes Erie or Huron, where fruit growth is delayed. However, we still have some bloom remaining, and lots of new bloom has appeared on young wood this week. Growers are looking to get their petal fall sprays as soon as possible. Thinning has started at many farms and will be especially challenging this season. With warm temperatures predicted this week, it appears there will be stress on the tree and therefore thinners will work very well.

A few apple growers are seeing apple tree death, mostly in lower lying area of blocks. This is due to cold damage on trees that were not fully hardened during the severe cold temperatures in the winters of 2014 and 2015. Affected trees generally have sections of bark on the trunk or lower scaffold branches with a scruffy or flaky appearance. These trees will most likely die over this or next season. This delayed winter injury will continue to show up for several years.

The only new insect pests to report this week in apples are codling moth trap catch and brown stink bug. Codling moth trap catch numbers are generally not at the biofix levels yet. Oriental fruit moth trap catch continues to rise, with most conventional blocks at biofix. Apple growers will need to be on the lookout for plum curculio and tarnished plant bugs any day now. A few mullein bugs continue being found. I am still finding small larvae of obliquebanded leafroller, redbanded leafroller and fruittree leafroller. A few apple blocks have rosy apple aphids and green apple aphids. Spotted tentiform leafminer adult trap catch has declined again this past week. Beneficials continue to be found in higher numbers, including lady beetle larvae, minute pirate bugs, lacewings and syrphid flies.

Powdery mildew continues to be found in more apple blocks. There is a slight curl or upwards roll in the expanding leaves as well as a few spots on the upper leaf surface.

We did not have any apple scab wetting events at most of our Michigan State University Enviro-weather stations over this past week. My last apple scab spore catch at my apple scab spore trapping location was May 16, catching 145 spores. The numbers of spores are declining as primary apple scab season is working its way to the end. We are not at the end of primary apple scab season.

Fire blight infection has not been an issue at most farms this past week, but the MSU Enviro-weather website MaryBlyt model is predicting high EIP numbers starting today, May 24. With bloom still present, growers may need to be ready for streptomycin applications. MSU Extension advises growers to watch blocks and varieties where fire blight was a problem last season, as well as be on the lookout for oozing fire blight cankers where it was a problem last season.

Pears are mostly 8 to 11 millimeters in diameter. Pear psylla adults continue to fly with nymphs and eggs present as well.

Peaches are 6 to 8 millimeters in size for growers in the south and out of the shuck for most others to the north. Oriental fruit moth trap catch continues to be seen at many farms, with most conventional blocks at biofix. Most growers have a good crop of peaches this season.

Sweet cherries are 8 to 10 millimeters in diameter. Tarnished plant bugs were reported last week in sweet cherry. Brown rot control sprays continue being made.

Tart cherries are mostly at shuck split to 5 millimeters in diameter.

Plums are at 6 millimeters in diameter for European types and Japanese types are mostly 9 millimeters in diameter. However, some Japanese varieties have little to no crop this season.

Small fruits

Grapes took on a good spurt of growth this past week; canes have 4 to 6 inches of new growth for Concord types and mostly at the same stage of shoot growth for European varieties.

Strawberries are at full bloom at most farms. Flower trusses and new leaves continue emerging from the crown. Fungicide cover sprays are being applied to protect for gray mold infections. Most strawberry growers have frost-protected twice in the last week. Strawberry clipper or clipped buds continue being found at several farms, as have spittle bugs at a few farms. Angular leaf spot continues being found on leaves at a few farms.

Raspberry shoots and leaves continue emerging for summer fruiting types, with 3 to 4 inches of new shoot growth. Flower buds continue emerging on summer raspberries. New canes continue emerging from the ground in fall raspberries; the longest canes are 8 to 12 inches in length.

Blueberries remained at full bloom for most varieties. Blueberry stem gall wasp are emerging from overwintering galls and are looking to lay eggs on new shoots. As soon as bees are out, control sprays need be made for this pest. I have not found any signs of mummy berry mummies on the ground this season.

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