Southwest Michigan apple maturity report – Sept. 11, 2019

Taffy apples and Galas are being targeted for harvest in southwest Michigan.

General apple harvest comments

Recent dry and hot weather has increased the need for trickle irrigation in sandy sites for high density apples on dwarfing rootstock. Area growers are busy picking Jonathan and Empires for taffy apples, McIntosh and Early Fuji. Some spot picking of Gala is underway. Honeycrisp harvesting has slowed, generally waiting for more attractive skin coloring.

Brown marmorated stink bug has been a minor pest so far this year. The speculation is that the large-scale migration of the summer generation of this insect is triggered by drying down of soybeans, which are generally still green in the area.

Please be aware that samples we collect for this report are from the central Berrien County region, targeting more mature fruit on the outside of the tree canopy. Fruit in the interior of the tree will be less advanced than shown here. Sites with heavier soils and greater crop loads will generally be less mature.

Apple maturity in southwest Michigan for apples harvested Sept. 9-10, 2019

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Mac

16.0 (16.0-16.1)

3.6 (3.2-4.0)

12.0

Honeycrisp

16.0 (14.0-19.2)

3.8 (1.6-6.2)

11.9

Early Fuji

18.8 (18.0-19.3)

4.4 (3.2-5.8)

13.5

Gala

20.6 (18.3-23)

4.3 (2.0-6.4)

11.5

Jonathan

19.0 (18.0-21.0)

3.0 (3.0-3.0)

11.2

Empire

19.4 (18.0-22.0)

2.2 (2.2-2.5)

11.2

Jonagold

19.3 (18.0-20.0)

2.4 (2.0-3.4)

11.6

Individual variety results

McIntosh

The current starch test average of 3.6 is still below the recommended target starch index of 5. Average firmness is now approximately 16 pounds, the minimum recommended for long-term controlled atmosphere (CA) storage. Predicted peak harvest date for central Berrien County is Sept. 16. In cool seasons, like 2019, McIntosh tend to harvest earlier than Gala. Macs are being harvested in the area.

McIntosh maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 3

17.0 (17.0-17.0)

3.3 (3.0-3.6)

12.4

Sept. 10

16.0 (16.0-16.1)

3.6 (3.2-4.0)

12.0

Gala

Target starch index for maturity for this variety is 3. The current average 4.3 jumped from last week’s 2.7, but the range is wide, with some blocks testing as high as 6.4. Relative firmness is averaging 21, about the same as last week, with the minimum firmness of 18 pounds recommended for long-term CA storage. Predicted peak harvest date for central Berrien County is Sept. 14. Skin color is good on many blocks. Some fruit cracking has been noted for sites with advanced starch readings.

Gala maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 3

21.1 (20.0-23.0)

2.7 (1.4-4.4)

10.8

Sept. 10

20.6 (18.3-23)

4.3 (2.0-6.4)

11.5

Honeycrisp

The current average is 3.8 compared to 2.5 for last week, with a target mature starch index of 3.5 for this variety. The current average firmness of 16 pounds, compared to last week’s 18.3, is below the general guideline of 17 pounds for best long-term CA storage. The predicted peak harvest date is Sept. 20 for central Berrien County. Blocks with light crops, common in southwest Michigan this year, will generally harvest earlier than those with normal or heavier crops. As is typical with this variety, there is a tendency for drop, especially for large fruit. Use of stop drop is important to avoid loss.

Honeycrisp maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 3

18.3 (17.0-20.0)

2.5 (1.8-3.8)

12.0

Sept. 10

16.0 (14.0-19.2)

3.8 (1.6-6.2)

11.9

Early Fuji

A starch test of 3 is generally used as the target for mature for this variety, compared to the current average of 4.4. The general guideline is 18 pounds for best long-term CA storage, although this variety is generally used for direct fresh sales rather than long-term storage. The current average is 18.8 pounds. The predicted peak harvest date is Sept. 10 for central Berrien County.

Early Fuji maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 3

19.2 (19.0-19.4)

2.5 (3.0-4.0)

12.9

Sept. 10

18.8 (18.0-19.3)

4.4 (3.2-5.8)

13.5

Jonathan and Empire

Jonathan and Empire were sampled for the first time this week. These two varieties are generally utilized as taffy apples, with less concern about reaching ideal maturity. For both varieties, 3.5 is the target starch test for mature apples destined for fresh market. Predicted harvest dates for fresh market for central Berrien County are the last week of September.

Jonagold 

Jonagold was sampled for the first time this season. Starch conversion is averaging 2.4, with 3.5 as the target for mature for this variety. The predicted peak harvest date is Sept. 30 for central Berrien County. Fruit firmness averaged 19.3 pounds with the general guideline of a minimum of 17 pounds firmness for best long-term CA storage. This variety has a ways to go before it is mature for long term storage.

Normal and predicted 2019 peak harvest dates for apple varieties in central Berrien County in southwest Michigan based on weather data at the Southwest Michigan Research and Extension Center, Benton Harbor, MI.

Variety

Normal date

2018 Predicted peak harvest date

2019 Predicted peak harvest date

Paula Red

Aug. 22

 Aug. 20

Aug. 28

Zestar

Aug. 22

 Aug. 20

Aug. 28

Gingergold

Aug. 20

 Aug 18

Aug. 26

McIntosh

Sept. 10

 Sept 8

Sept. 16

Gala

Sept. 8

 Sept 6.

Sept. 14

Early Fuji

Sept. 3

 Sept. 1

Sept. 10

Honeycrisp

Sept. 13

 Sept. 13

Sept. 20

Empire

Sept. 19

 Sept. 23

Sept. 26

Jonathan

Sept. 22

 Sept. 24

Sept. 30

Jonagold

Sept. 22

 Sept. 24

Sept. 30

Golden Delicious

Sept. 25

 Sept. 27

Oct. 1

Red Delicious

Sept. 28

 Oct. 1

Oct. 7

Ida Red

Oct. 5

 Oct. 8

Oct. 15

Rome

Oct. 5

 Oct. 8

Oct. 15

Fuji

Oct. 20

 Oct. 22

Oct. 28

Braeburn

Oct. 20

 Oct. 22

Oct. 28

Goldrush

Oct. 26

 Oct. 28

Nov. 3

 

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.)

 


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