MSU Extension

General apple harvest comments

This will be our final apple maturity report from the southwest Michigan region for 2016. We appreciate the many growers who provided samples for testing.

Fruit quality was generally good this year with only some issues with bitter pit on some varieties such as Honeycrisp and Braeburn, and coloring problems on Honeycrisp and older Jonagold strains. Red Delicious crop volume was less than expected. This year, we saw more than usual oriental fruit moth larvae entry into the calyx end of fruit. In some cases, the injury was difficult to see without close inspection.

Brown marmorated stink bug activity continues to go up and down with the temperature, with many more bugs found on fruit in sunny and warm days. Stink bug damage can be confused with bitter pit symptoms, which are common on bitter pit-prone varieties such as Braeburn, Honeycrisp, Jonagold and, to a lesser extent, Golden Delicious and Red Delicious. Stink bug damage will tend to be worse on edges of blocks close to woods where the bugs will congregate on some wild tree types. See “Michigan brown marmorated stink bug report for Oct. 5, 2016” from Michigan State University Extension for more information about stink bugs this season and prospects for next season.

The normal and estimated 2016 peak harvest dates for apple varieties in southwest Michigan table is included at the end of this report. Data in the following tables are based on samples collected from commercial orchards in the central Berrien County area. Firmness and starch ranges are the observed low and high mean values. The summaries for Evercrisp and Cameo are based on samples from the Southwest Michigan Research and Extension Center variety trial.

Individual variety results

IdaRed was sampled for the fourth week. Most of the Idared blocks in the area are harvested. Skin color is 50 to 90 percent pink blush on mainly green back. The current starch index of 3.8 has reached the target of 3.5 or more recommended for fresh market, and the current average firmness of 15.5 pounds is still above the mark of 15 pounds considered suitable for long-term controlled atmosphere (CA) storage. Some individual sites are already below this firmness. The predicted peak harvest date for fresh market for central Berrien County was Sept. 30.

Fuji was sampled for the third week. Background color was still largely green with 40 to 90 percent blush, depending on the strain. The current starch index of 6.4 made a sizable jump compared to last week and is well-above the minimum recommended target of 3.0 for fresh market, and the current firmness of 15.5 pounds is below the recommended range for mid-term CA storage. At this stage of maturity, Fuji are best suited for more immediate sales. The internal maturity is ahead of the predicted harvest date of Oct. 14 for fresh market in central Berrien County.

Braeburn was sampled for the third week. Background color is still green with 20 to 98 percent blush, depending on the variety. The current starch index of 3.6 has reached the target of 3.0 for fresh market, and the current firmness of 20.1 pounds, slightly lower than last week, will still allow harvest to be delayed for better size and quality. The predicted peak harvest date for fresh market in central Berrien County is Oct. 14.

Rome was sampled for the second time this week. Background color is green with 60 to 100 percent blush, depending on the variety. The current starch index of 3.9 has reached the target 3.0 for fresh market, and the current firmness of 19.3 pounds has been holding and will allow harvest to be delayed for better size and quality. Harvesting Romes for processing has already started in some blocks in order to avoid red color skin color bleeding into the flesh. The predicted peak harvest date for fresh market in central Berrien County was Sept. 30.

Predicted peak fresh market apple harvest dates

These dates are an estimate and will be affected by the apple strain, rootstock, crop load, fertility, soil type, and other factors including current weather. Cameo, not in the table, harvests between Red Delicious and Idared, and Evercrisp is pegged to harvest after Fuji, but before Goldrush.

Source: R. Beaudry, P. Schwallier, and M. Lennington. 1993. Apple maturity prediction: an extension tool to aid fruit storage decisions. HortTechnology 3:233-239.

*Firmness is measured with a mechanical 11-millimeter wide probe inserted into the pared flesh of a fruit to a distance of 8 millimeters. Starch index is measured on equatorial cross section of an apple stained with iodine solution and rated using the Cornell University starch-iodine index chart for apples on a 1-8 scale (Predicting Harvest Date Window for Apples by Blanpied and Silsbey, Cornell Extension Bulletin 221.)

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.

The Southwest Michigan Apple Harvest Report is produced by Bill Shane, fruit specialist, Southwest Michigan Research and Extension Center, Benton Harbor, Michigan. Email: shane@msu.edu.