Southwest Michigan apple maturity report – September 21, 2016

Golden Delicious harvest is underway and Red Delicious harvest is around the corner. Weather has been generally good for harvesting.

General apple harvest comments

Warm weather has pushed along internal fruit ripening but slowed blush development. Empires are slow to mature this year. The Golden Delicious we have tested from central Berrien County are generally mature enough to harvest, as well as some Red Delicious. Brown marmorated stink bug trap catches in the southwest region continue to increase.

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. 19

Variety

Firmness Lbs. (range)

Starch (range)

Brix %

Empire

18.0 (17.0-19.0)

3.0 (2.4-4.0)

12.0

Jonagold

17.1 (16.2-18.0)

4.7 (3.2-6.0)

13.0

Jonathan

16.2 (16.0-16.4)

5.7 (4.3-6.8)

12.2

Golden Delicious

17.2 (16.0-18.4)

3.0 (2.6-3.8)

12.3

Red Delicious

17.8 (17.0-19.0)

3.1 (2.4-4.2)

10.2

IdaRed

18.0 (17.0-19.0)

2.8 (2.6-3.0)

11.6

Individual variety results

Empire was sampled for the second time this week. The starch conversion reading this week is 3.0, still below the target value of 3.5 for fresh market. Background color was generally green. Retain applications are holding back maturity including firmness and color development, but even untreated fruit appear to be later than the predicted peak harvest date of Sept. 12 for fresh market for central Berrien County. Firmness of 18 pounds is still in the range sufficient for long-term controlled atmosphere (CA) storage and 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

Sept. 20

18.0 (17.0-19.0)

3.0 (2.4-4.0)

12.0

Jonathan predicted peak harvest date for central Berrien County is Sept. 16. The current starch test is 5.7, which is considered sufficient for successful CA storage and the firmness of 16.2 is still adequate for long-term CA, but is expected to drop into the firmness range for midterm CA storage. Most area Jonathans have already been harvested for taffy apples.

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

Sept. 19

16.2 (16.0-16.4)

5.7 (4.3-6.8)

12.2

Jonagold was sampled for the second week. Background color is still generally green but shows some brightening. Starch index is now averaging 4.7, reaching the target starch index of 3.5 for fruit destined for fresh market. The current flesh firmness is averaging 17.1, still suitable for long-term CA storage, but may soften to midterm CA storage firmness by this time next week. 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

Sept. 19

17.1 (16.2-18.0)

4.7 (3.2-6.0)

13.0

Golden Delicious was sampled for the second week. Background color is still generally green. The current starch index of 3 is at the minimum of 3 recommended for fresh market, and the current firmness of 17.2 pounds is good for long-term CA storage—once they fall to 16 pounds then the recommendation is for midterm CA storage. 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

Sept. 19

17.2 (16.0-18.4)

3.0 (2.6-3.8)

12.3

Red Delicious was sampled for the first time this week. Blush is 80 to 98 percent red on green background. Current starch index of 3.1 is above the minimum target of 2.5 for fresh market, and the average firmness of 17.8 is suitable for long-term CA storage. The predicted peak harvest date for fresh market for central Berrien County is Sept. 22.

Red Delicious maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 19

17.8 (17.0-19.0)

3.1 (2.4-4.2)

10.2

Idared was sampled for the first time this week. Background color was generally green with very little blush. The current starch index of 2.8 is below the target 3.5 for fresh market, and the current firmness of 18 pounds will allow harvest to be delayed. The predicted peak harvest date for fresh market for central Berrien County is Sept. 30.

Idared sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 19

18.0 (17.0-19.0)

2.8 (2.6-3.0)

11.6

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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