Southwest Michigan apple maturity report – October 8, 2014

Harvest of Golden Delicious in southwest Michigan is well underway with Red Delicious ramping up. Rain has hampered harvesting somewhat. Fruit size is generally very good where fruit were thinned properly.

General comments

Brown marmorated stink bug catches over the past week have been low. It appears that problems from this pest this year will end up being minor. Catches of oriental fruit moth are tapering down as we get into cool evenings.

Most of the Jonagolds and Golden Delicious in central Berrien County have been picked. Growers are focusing their attention on Red Delicious.

Next week will be the last Michigan State University Extension apple maturity report from southwest Michigan.

Specific apple variety comments

Golden Delicious orchards in central Berrien County are testing an average of 16.3 pounds firmness with an average starch index of 5.7. They now have sufficient internal maturity for good flavor for immediate sales and sufficient firmness still for mid-term controlled atmosphere (CA) storage. Minimum recommended firmness for mid-term CA is 16 pounds with a starch reading of 3 or more. Current brix is at 13.9, slightly better than last week.

Golden Delicious maturity summary

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2014

16.0

4.2

13.3

10/6/2014

14.6

5.8

12.1

10/6/2014

16.8

6.4

15.3

10/6/2014

16.3

6.6

13.5

10/6/2014

18.4

5.2

16.7

10/6/2014

15.8

6.2

12.5

Current average

16.3

5.7

13.9

Last week’s average

17.9

3.8

13.7

The predicted long-term storage harvest date for Golden Delicious in 2014 at the Southwest Michigan Research and Extension Center (SWMREC) is Oct. 3. Target starch index for Golden Delicious is 3.

Red Delicious picked Monday this week, Oct. 6, are averaging 17 pounds firmness, which is at the minimum recommended firmness for fruit destined for mid-term CA. Starch conversion index averaged 3.7, well into the mature zone for long-term CA. Based on these tests, all blocks are past the optimum point for long-term CA, most for mid-term CA, and some are best suited for short-term CA storage or current fresh market sales. A few apples are showing watercore and moldy core symptoms. Fruit size is good this year.

Red Delicious maturity summary

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2014

16.4

2.8

11.7

10/6/2014

16.8

4.4

12.1

10/6/2014

17.2

3.4

11.6

10/6/2014

16.9

5.2

13.8

10/6/2014

17.3

3.0

10.9

10/6/2014

17.5

3.4

14.3

Current average

17.0

3.7

12.4

Last week’s average

18.0

2.6

11.6

The predicted long-term storage harvest date for Red Delicious in 2014 for central Berrien County is Oct. 7. Target starch index for Red Delicious is 2.5.

Ida Red tested this week are averaging 17 pounds firmness, still above the 16 pound minimum recommended firmness for fruit destined for long-term CA. Starch conversion index averaged 3.1, below the 3.5 sought for best long-term CA. Based on these tests, harvest could be delayed. So far, few Ida Reds have been harvested in the area.

Ida Red maturity summary

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2014

17.8

3.4

12.8

10/6/2014

15.8

2.8

13.4

10/6/2014

17.3

2.8

13.6

10/6/2014

17.1

3.2

11.5

Current average

17.0

3.1

12.8

Last week’s average

18.2

2.2

12.0

The predicted long-term storage harvest date for Ida Red in central Berrien County is Oct. 11. Target starch index for Red Delicious is 2.5

Fuji picked this week are averaging 19.4 pounds firmness, above the 18 pound minimum recommended firmness for fruit destined for long-term CA. Starch conversion index averaged 3.6, above the target of at least 3.0 for good flavor for fruit to be consumed soon. Based on these tests, some blocks could be harvested successfully for long-term CA storage. Fruit maturity has not changed much over the past week except a jump in the brix from 13 to 14.7. The excellent firmness will allow harvest to be delayed to wait for better size, skin color, brix and eating quality. Fruit skin background color is still noticeably green in color and in flavor. A small number of fruit are showing a little amount of watercore.

Fuji (traditional season strains) maturity report

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2012

16.9

4.4

14.1

10/6/2012

19.8

3.6

16.2

10/6/2012

18.8

2.8

13.1

10/6/2012

18.9

3.6

14.9

10/6/2012

22.6

3.8

15.4

Current average

19.4

3.6

14.7

Last week’s average

19.6

3.3

13.0

The predicted long-term storage harvest date for Fuji in central Berrien County is Oct. 25. Target starch index for Fuji is 2.5.

Rome picked this week for sampling are averaging 21.7 pounds firmness, above the 18 pound minimum recommended firmness for fruit destined for long-term CA storage. Starch conversion index averaged 3.1, above the target of 3.0 for successful long-term CA storage. Based on these tests, some blocks could be harvested successfully for long-term CA storage. However, the excellent firmness will allow harvest to be delayed to wait for better size, skin color, brix, and eating quality if intended for fresh market sales. Most Romes for processing in southwest Michigan have already been harvested to minimize red color bleeding into the flesh from the skin.

Rome maturity summary

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2012

23.2

3.2

12.1

10/6/2012

21.0

3.0

12.6

10/6/2012

20.8

3.0

11.8

Current average

21.7

3.1

12.2

The predicted long-term storage harvest date for Romes in central Berrien County is Oct. 15. Target starch index for Romes is 3.0.

Braeburn picked this week are averaging 23.2 pounds firmness, way above the 18 pound minimum recommended firmness for fruit destined for long-term CA storage. Starch conversion index averaged 2.2, below the target of 3.0 for successful long-term CA storage. Based on these tests, harvest of these blocks should be delayed to wait for better size, skin color, brix and eating quality.

Braeburn maturity summary

Date picked

Firmness (pounds)

Starch index

Brix

10/6/2012

23.5

2.4

10.5

10/6/2012

22.8

2.0

10.4

10/6/2012

22.3

1.8

12.4

10/6/2012

24.1

2.6

13.5

Current average

23.2

2.2

11.7

The predicted long-term storage harvest date for Braeburn in central Berrien County is Oct. 25. Target starch index for Braeburn is 3.

Suggested firmness and starch index levels for long-term and shorter-term CA storage for selected varieties

Variety

Firmness (pounds)*

Starch Index*

Short CA

Mid-CA

Long CA

Export CA

Mature

Over mature

Golden Delicious

15

26

17

 

3.0

6.5

Red Delicious

16

17

18

 

2.5

5.0

Ida Red

14

15

16

 

3.5

6.0

Fuji

16

17

18

 

3.0

7.0

Rome

15

16

18

 

3.0

5.5

Braeburn

16

17

18

 

3.0

7.0

*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”).

Contact Bill Shane at the SWMREC, 269-944-1477 ext. 205, or 269-208-1652, if you would like to have samples from your farm tested for maturity. Statewide reports will generally be available on the MSU Apple Maturity Program and Reports page by Wednesday afternoon each week.

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