Southwest Michigan apple maturity report – September 14, 2016

Honeycrisp harvest is underway in southwest Michigan. Stink bug trap catches have increased significantly over the past week.

General apple harvest comments

Gala harvest is still underway in area orchards. Hot weather has slowed skin color development for some varieties. Jonathans and some Empire are being picked for taffy apples. Honeycrisp harvest is increasing. Brown marmorated stink bug trap catches in the southwest region have increased significantly over the past week.

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.

Apple maturity in southwest Michigan for apples harvested Sept. 12

Variety

Firmness Lbs. (range)

Starch (range)

Brix %

Honeycrisp

15.5 (15.0-16.4)

5.2 (4.4-6.2)

13.5

Empire

18.3 (17.2-19.1)

2.5 (1.8-3.0)

11.7

Jonagold

18.2 (17.7-19.0)

2.7 (2.2-4.0)

12.4

Jonathan

17.8 (17-18)

3.7 (3.0-4.6)

11.8

Golden Delicious

18.2 (17-19)

2.2 (1.6-2.8)

11.7

Individual variety results

Last week, Early Fuji tested mature with a starch conversion reading of 5.2, well over the target starch index 3, and firmness down to 15.6 pounds. The predicted peak harvest date for the Southwest Michigan Research and Extension Center site is Aug. 23, but hot days and warm nights slowed blush development and background color development needed for best flavor and appearance.

Early Fuji 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 7

15.6 (14.5-16.5)

5.2 (3.6-5.8)

12.3

Honeycrisp was sampled for the second time. Target starch index for this variety this week is 3.5 and the predicted peak harvest date for central Berrien County is Sept. 3. All Honeycrisp sites tested mature for long-term controlled atmosphere (CA) storage, skin color ranged from poor to excellent. Some water core was detected. As is the case with Honeycrisp, there is a wide of ripening and some pre-harvest drop. Brix of 13.5 is approximately the same as last week. Firmness dropped about 1 pound since last week.

Honeycrisp 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 6

16.7 (16.2-18.1)

5.4 (4.8-6.2)

14.0

Sept. 12

15.5 (15.0-16.4)

5.2 (4.4-6.2)

13.5

Empire was sampled for the first time this week. The starch conversion reading this week is 2.5 compared to the target value of 3.5. Background color was generally green. Retain applications are holding back maturity including firmness and color development, but even untreated fruit appear to be behind the predicted peak harvest date of Sept. 12 for fresh market for central Berrien County. Good firmness will allow harvest to be delayed for better fruit quality development for fresh market and for higher quality processing uses.

Empire maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 12

18.3 (17.2-19.1)

2.5 (1.8-3.0)

11.7

Jonathan predicted peak harvest date for central Berrien County is Sept. 16. The current starch test is 3.7, which is considered sufficient for successful CA storage. However, skin background color is generally green and fruit intended for fresh market will improve with additional ripening on the tree.

Jonathan maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 12

17.8 (17-18)

3.7 (3.0-4.6)

11.8

Jonagold was sampled for the first time this week. Background color was generally green and the fruit taste green as well. Target starch index for fruit destined for fresh market is at least 3.5, and this week tested at only 2.7. Current firmness of 18.2 is still good and harvest can wait for more starch conversion and skin color development for fruit intended for fresh market. The target harvest date for central Berrien County for Jonagold is Sept. 16.

Jonagold 2016 maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 12

18.2 (17.7-19.0)

2.7 (2.2-4.0)

12.4

Golden Delicious was sampled for the first time this week. Background color was generally green with very little blush. Current starch index of 2.2 is below the target 3 for fresh market, and very firm flesh will allow harvest to be delayed. The predicted peak harvest date for fresh market for central Berrien County is Sept. 19.

Golden Delicious maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 12

18.2 (17-19)

2.2 (1.6-2.8)

11.7

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.

Normal and predicted 2016 peak harvest dates for apple varieties in southwest Michigan based on SWMREC weather data.

Variety

Normal date

2016 predicted date

Paula Red

8/22

8/12

Zestar

8/22

8/12

Gingergold

8/20

8/10

McIntosh

9/10

8/30

Gala

9/8

8/28

Early Fuji

9/3

8/23

Honeycrisp

9/13

9/3

Empire

9/18

9/12

Jonathan

9/22

9/16

Jonagold

9/22

9/16

Golden Delicious

9/25

9/19

Red Delicious

9/28

9/22

Ida Red

10/5

9/30

Rome

10/5

9/30

Fuji

10/20

10/14

Braeburn

10/20

10/14

Goldrush

10/26

10/20

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

Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety.

Variety

Firmness (pounds)*

Starch Index*

Short CA

Mid-CA

Long CA

Mature

Over mature

McIntosh

14

15

16

5

7

Gala

16

17

18

3

6

Honeycrisp

15

16

17

3.5

7

Empire

14

15

16

3.5

6

Early Fuji

16

17

18

3

7

Jonagold

15

16

17

3.5

5.5

Jonathan

14

15

16

3.5

5.5

Golden Delicious

15

16

17

3

6.5

Red Delicious

16

17

18

2.5

6

Idared

14

15

16

3.5

6

Fuji

16

17

18

3

7

Rome

15

16

18

3

5.5

*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: .(JavaScript must be enabled to view this email address).

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