Southwest Michigan apple maturity report – October 5, 2016

Golden Delicious harvest is nearly done and Red Delicious harvest has begun. Weather continues to be good for harvesting.

General apple harvest comments

Harvest is moving rapidly in southwest Michigan thanks to dry conditions. Controlled atmosphere (CA) storage facilities are filling quickly. Fruit quality is good and fruit maturation seems to be somewhat variable. This year we are seeing more than usual oriental fruit moth larvae entry into the calyx end of fruit. In some cases, the injury is difficult to see without close inspection.

Brown marmorated stink bug activity continues to increase as they move out of harvested field crops and seek new food sources. This insect can move into an orchard, cause damage to fruit and move out again without being detected. So far we have not found traps to be reliable indicators of local hot spots. Stink bug damage can be confused with bitter pit symptoms, which are common on bitter-pit prone varieties such as Braeburn, Honeycrisp and Jonagold and to a lesser extent on 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.

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 Oct. 3, 2016

Variety

Firmness Lbs. (range)

Starch (range)

Brix %

Golden Delicious

15.2 (15.0-16.1)

5.5 (4.6-6.6)

12.2

Red Delicious

16.9 (16.0-18.0)

4.9 (3.4-7.0)

11.4

IdaRed

16.2 (16.0-17.0)

3.1 (2.4-4.0)

12.4

Fuji

16.5 (15.0-18.0)

4.2 (3.6-4.6)

12.5

Braeburn

21.0 (20.0-22.0)

2.6 (1.6-3.4)

11.1

Rome

20.7 (20.0-21.3)

3.1 (3.0-3.2)

10.6

Individual variety results

Golden Delicious was sampled for the fourth week. Most blocks in central Berrien County have been partially or completely picked. More fruit are showing some slight yellow background, but is still generally green. Pink blush ranges from trace to 40 percent. The current starch index of 5.5 is well above the minimum of three recommended for fresh market, and the current average firmness of 15.2 pounds is between the ranges for mid- and short-term storage. The predicted peak harvest date for fresh market for central Berrien County was Sept. 19.

Golden Delicious maturity sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Sept. 12

18.2 (17.0-19.0)

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

Oct. 4

15.2 (15.0-16.1)

5.5 (4.6-6.6)

12.2

Red Delicious was sampled for the third week. Blush is 60 to 100 percent red on green background. Current starch index of 4.9 is well above the minimum target of 2.5 for good quality fresh market, and the average firmness of 16.9, about 1 pound less than last week, is in the range for mid-term CA storage. Some slight internal water core is common in a few sites. The predicted peak harvest date for fresh market for central Berrien County was 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

Oct. 4

16.9 (16.0-18.0)

4.9 (3.4-7.0)

11.4

IdaRed was sampled for the second week. Background color was generally green with very little blush. The current starch index of 3.1 is still below but approaching the target of 3.5 for fresh market, and the current firmness of 16.2 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 was 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

Oct. 4

16.2 (16.0-17.0)

3.1 (2.4-4.0)

12.4

Fuji was sampled for the second week. Background color was green with 40 to 90 percent blush, depending on the strain. The current starch index of 4.2 has is above the minimum recommended target of 3.0 for fresh market, and the current firmness of 16.5 pounds is in range for 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 12.5

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

Oct. 4

16.5 (15.0-18.0)

4.2 (3.6-4.6)

12.5

Braeburn was sampled for the second week. Background color is still green with 20 to 70 percent blush, depending on the variety. The current starch index of 2.6 is approaching the target of 3.0 for fresh market, and the current firmness of 21 pounds, about the same as last week, 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

Oct. 4

21.0 (20.0-22.0)

2.6 (1.6-3.4)

11.1

Rome was sampled for the first time this week. Background color is green with 60 to 100 percent blush, depending on the variety. The current starch index of 3.1 has reached the target 3.0 for fresh market, and the current firmness of 21 pounds will allow harvest to be delayed for better size and quality. Harvesting of 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 for central Berrien County was Sept. 30.

Rome sampling for the harvest season

Date of sample

Firmness Lbs. (range)

Starch (range)

Brix %

Oct. 4

20.7 (20.0-21.3)

3.1 (3.0-3.2)

10.6

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. Cameo, not in the table, harvests between Red Delicious and Idared, and Evercrisp is pegged to harvest after Fuji, but before Goldrush.

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.

VarietyFirmness (pounds)*Starch Index*
Short CAMid-CALong CAMatureOver 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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