Southeast Michigan fruit regional report – April 7, 2015

Spring is off to a slow start following two brutally cold winters, colder than most fruit growers can remember.

Posted on April 7, 2015 by Bob Tritten, Michigan State University Extension

Weather

Winter. We have just experienced the second cold winter in a row. In fact, most of our Michigan State University Enviro-weather stations reported even colder temperatures this winter than last. Many farms and MSU Enviro-weather stations recorded low temperatures this winter in the range of -22 to -28 degrees Fahrenheit, occurring in two distinct windows: one in mid-January and the second in mid- to late February. There was another unusual cold event in early March as well.

We have experienced cold damage to flower buds, twigs and tree trunks on most of our stone fruit crops, pears, summer brambles, blueberries and grapes. Damage to apples has not been detected yet, but more time is needed to determine potential damage. While it is a bit early in the season to make bold crop loss predictions, needless to say we will have some fruit crops with a significant crop reduction or complete loss, and some with longer lasting effects to the woody tissue in the trunks and scaffold branches. More details to follow in this report.

Spring. Cool to cold temperatures have held back development of our fruit crops; most are slightly behind normal. With warmer daytime temperatures the last few days, fruit crops are just beginning to show signs of bud swell and spring growth. Cold nighttime temperatures have kept crop development to a minimum.

With a general lack of rain this spring, our soil moisture conditions are dry across the region. Ground preparation and planting is taking place much earlier than normal. Most growers are completing their winter pruning, brush chopping and removal, and general spring chores in the orchard, as well as just starting to tune-up and calibrate sprayers for the season.

East Michigan growing degree day (GDD) totals for March 1 to April 6, 2015

Tree fruits

Apples are at slight bud swell to silver tip for a few varieties. A few more warm days and we will begin to see green tip in Ida Reds and other early leafing varieties. I have not found bud damage in apples. Bud burst will be the time when a more accurate assessment can be made as to possible flower bud damage. Recall that last year there was significant damage to major scaffold branches and trunks that was not anticipated in apples. This damage was most pronounced in Golden Delicious and related strains. This damage did not begin to show up until mid-May or so, and resulted in total tree loss in many blocks. It is too early to assess this type of damage.

Pears show no movement and show some bud damage due to cold temperatures this winter. A more accurate assessment can be made at bud burst when whole blocks rather than individual buds can be assessed. A few pear psylla adults were flying yesterday, April 6.

Peaches are one of the most cold-tender tree fruits and flower bud loss is expected when temperatures fall below -13 F. Most injury occurs between -13 and -16 F. Most growers are experiencing significant flower bud losses, many appearing dehydrated and will be falling off in the next few weeks. It was so cold at many farms that I can see damage to twigs, scaffold branches and even trunks. This damage is showing up as brown- to cinnamon-colored cambium tissue.

Sweet and tart cherries remain dormant to the slightest bud swell and show damage to the fruit buds even on good cherry sites. Tart cherries mostly show less damage in the colder sites than sweets; generally two to three dead florets are being seen in the flower cluster or bud. These levels of damage are greater than damage from a light frost during bloom or a wet, rainy day during pollination at bloom.

Plum damage is extensive in Japanese plums with less in European plums as they are more cold hardy.

Small fruits

Grapes show no movement. There is some damage in Concords and extensive damage to wine grapes varies, however damage varies greatly between varieties and sites.

Strawberry leaves are not emerging from the ground, even at our most southern farms. According to Michigan State University Extension recommendations, it is a bit early to remove mulch.

Raspberry canes of summer fruiting types have a significant amount of cambium browning, indicating potential winter injury. Fall raspberries were mowed a month ago at most farms.

Blueberry buds are starting to show some bud swell. Initial bud assessments indicate damage to flower buds. The damage takes two forms: dead flowers in the flower cluster, or bud and withered shoot tips that dried from cold winds and subfreezing conditions. Generally, what we are seeing is several dead florets per bud.

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