Northwest Michigan fruit update – May 1, 2018

The snow is finally melting and growers are clearing brush, planting trees and preparing for early season fruit management.

Growing degree day accumulations as of April 23, 2018, at the Northwest Michigan Horticulture Research Center








28 Yr. Avg.

















2018 Growth Stages as of April 23, 2018

  • Bartlett pear – Dormant
  • Potomac pear – Dormant
  • Mac – Early silver tip
  • Gala – Dormant
  • Red Delicious – Ear. silver tip
  • HoneyCrisp – Ear. silver tip
  • Montmorency – Early bud swell
  • Balaton – Bud swell
  • Hedelfingen – Bud swell
  • Gold – Bud swell
  • Napoleon – Bud swell
  • Riesling – Dormant

 Weather report

It has been a slow start to the 2018 season. So far, we have accumulated 75.6 growing degree days (GDD) base 42 degrees F and 24.2 GDD base 50 degrees F. These accumulations are significantly lower than our 28-year average of 214.9 GDD base 42 degrees F and 89.9 GDD base 50 degrees F. Our records show that in the last 15 years, this season is most similar to the degree day accumulations of spring 2014. Temperatures for the remainder of the week are predicted to be in the 60s, warmer and more seasonal for this time of year. There is also a good chance for rain in the forecast beginning on Wednesday through Friday (May 2-4). We expect crop development to move along quickly with warm temperatures and rainfall. Despite the pockets of snow still present in orchards, conditions are drying out quickly with the warmth and low humidity. There is a severe fire danger reported across northwest Michigan, so burning brush is not recommended at this time.

Crop report

Cherry buds are just starting to swell, and some side green has been observed in tart cherries at the NWMHRC. Sweet cherries are also starting to swell, and apples at the station are at early silvertip. With the recent snowmelt, Michigan State University Extension reports growers have been able to move in and remove brush, and growers have been planting trees during this stretch of nice weather.​

There are concerns about the brine cherry situation in northwest Michigan. We are currently investigating horticultural tactics that may be available for minimizing the crop in blocks where growers do not intend to harvest the fruit. More information will be forthcoming. With this current situation, many growers have questions about the finances associated with decision-making; please call us at the station if you need help.

Pest report

While spots of snow remain in orchards, growers have been taking advantage of the stretch of warm weather to not only clear brush and plant trees, but to prepare delayed dormant management approaches for pests and diseases.

San Jose scale – a pest of pome and stone fruits – has been a hot topic lately as this pest has become ubiquitous in orchards across the state.  Lecanium scales have also become more noticeable in sweet cherry orchards, particularly in blocks adjacent to woodlots with maple trees. Delayed dormant is the first chance in the season to take action against scales and mites and this strategy could be particularly important for growers with historically high populations/substantial scale damage. In our regions, we have continued to receive reports of sweet cherry orchards with scale densities that could cause substantial limb death. This pest is also gaining attention in apples and peaches in southerly Michigan regions. We have not observed San Jose scale causing damage in tart cherries.

In cherries, liquid formulations of chlorothalonil could be in short supply this season and this situation has raised concerns for growers that have used the special local need registration 24 (c) for post-shuck split use of Bravo WeatherStik. We remind growers that there are other efficacious cherry leaf spot fungicides available for use at this timing; please refer to the MSU Fruit Management Guide E-154 and future reports for additional information regarding cherry leaf spot management at this timing.

Most apples do not have green tissue present at this time, but growers have been planning for primary apple scab management in anticipation of green tissue showing up following recent warm temperatures and predicted wet weather. Like our colleagues in west Michigan, we will use Enviroweather and RIMpro models ( in our future scab reports.

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