Southwest Michigan apple maturity report – September 28, 2016

Golden Delicious harvest is continuing and growers are putting out bins for Red Delicious. Fuji is showing advanced development, but needs cool evenings to develop better skin color and sugar.

General apple harvest comments

Most Jonagold, Empire and some Golden Delicious fruit have been harvested in the area. Recent cooler weather has helped to color fruit and increase sugar content. Brown marmorated stink bug trap catches in the southwest region continue to increase and we have some reports of them feeding on apple fruit. Damage from this insect resembles bitter pit.

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. 27

Variety

Firmness Lbs. (range)

Starch (range)

Brix %

Empire

17.1 (15.0-19.0)

4.3 (3.0-5.2)

12.7

Jonagold

16.4 (15.4-18.0)

6.3 (4.8-7.0)

13.3

Golden Delicious

16.3 (15.4-18.0)

4.9 (2.6-6.4)

12.2

Red Delicious

17.8 (17.0-19.0)

3.8 (3.0-3.8)

10.5

IdaRed

17.4 (17.0-18.0)

2.6 (2.0-3.0)

11.8

Fuji

17.7 (17.0-19.0)

3.3 (3.2-3.4)

12.2

Braeburn

22.0 (21.2-23.0)

2.1 (1.4-3.0)

11.0

Individual variety results

Empire was sampled for the third week. The starch conversion reading this week is 4.3, now exceeding the minimum value of 3.5 recommended for best quality for fresh market. Background color is generally green, but is showing some white tint, indicating fruit maturation. This variety is harvesting later than the predicted peak harvest date of Sept. 12 for fresh market for central Berrien County. Firmness of 17.1 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

Sept. 27

17.1 (15.0-19.0)

4.3 (3.0-5.2)

12.7

Jonagold was sampled for the third week. Background color is still generally green, but shows some brightening. Some of the older Jonagold strains still have insufficient skin color for some markets and have been spot-picked. Starch index is now averaging 6.3, reaching the target starch index of 3.5 for fruit destined for fresh market. The current flesh firmness is averaging 16.4, and generally suitable for mid-term CA storage firmness. The target harvest date for central Berrien County for Jonagold is Sept. 16.

Jonagold 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

Sept. 27

16.4 (15.4-18.0)

6.3 (4.8-7.0)

13.3

Golden Delicious was sampled for the third week. Background color on a few apples are showing some slight yellow, but is still generally green. Pink blush ranges from trace to 40 percent. The current starch index of 4.9 is above the minimum of 3 recommended for fresh market, and the current average firmness of 16.3 poundsis still good for long-term CA storage, but a few sites are below 16 pounds and more suitable for mid-term 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

Sept. 27

16.3 (15.4-18.0)

4.9 (2.6-6.4)

12.2

Red Delicious was sampled for the second week. Blush is 60 to 100 percent red on green background. Current starch index of 3.8 is above the minimum target of 2.5 for good quality fresh market, and the average firmness of 17.8, about the same as last week, is suitable for long-term CA storage. Some watercore is showing in a few apple samples. 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

Sept. 27

17.8 (17.0-19.0)

3.8 (3.0-3.8)

10.5

IdaRed was sampled for the second week. Background color was generally green with very little blush. The current starch index of 2.6 is still below the target 3.5 for fresh market, and the current firmness of 17.4 pounds will allow harvest to be delayed. Firmness down to approaching 15 pounds is considered suitable for long-term CA storage. 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

Sept. 27

17.4 (17.0-18.0)

2.6 (2.0-3.0)

11.8

Fuji was sampled for the first time this week. Background color was green with 40 to 90 percent blush, depending on the strain. The current starch index of 3.3 has reached the minimum target 3.0 for fresh market, and the current firmness of 17.7 pounds is between the range for long- and mid term CA storage. The predicted peak harvest date for fresh market for central Berrien County is Oct. 14. The internal maturity is ahead of the predicted harvest date, but eating quality will improve by waiting for less background green color and higher brix, now testing 12.2

Fuji sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 27

17.7 (17.0-19.0)

3.3 (3.2-3.4)

12.2

Braeburn was sampled for the first time this week. Background color is green with 20 to 70 percent blush, depending on the variety. The current starch index of 2.1 is below the target 3.0 for fresh market, and the current firmness of 22 pounds will allow harvest to be delayed for better size and quality. The predicted peak harvest date for fresh market for central Berrien County is Oct. 14.

Braeburn sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 27

22.0 (21.2-23.0)

2.1 (1.4-3.0)

11.0

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

Braeburn

16

17

18

3

7

*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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