NOVEL CORONAVIRUS UPDATES AND RESOURCES

Southwest Michigan apple maturity report – Sept. 25, 2019

Honeycrisp harvest continues in southwest Michigan, with Golden Delicious and a very few Red Delicious being picked. Fruit color is generally very good.

Sooty blotch and flyspeck symptoms
Sooty blotch and flyspeck symptoms are common on apples in abandoned orchards. Photo by Bill Shane, MSU Extension.

General apple harvest comments

Most Galas, Empires and McIntosh have been harvested in the area. The generally dry conditions have allowed harvest to move quickly. Labor supplies seem to be generally adequate.

White tufts from woolly apple aphid infestations are showing up on Fuji branches. Brown marmorated stink bugs numbers increased significantly again (tripled) over the past week with damage starting to show up on fruit and vegetables. Stink bugs are starting to cluster on fruit and gather on buildings. Fruit are generally clean, however sooty blotch and flyspeck disease symptoms are common on unprotected fruit in abandoned orchards, indicating that fungicide protection has been needed.

Samples collected 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. 25, 2019

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Honeycrisp

15.4 (14.0-16.2)

6.4 (4.6-8.0)

12.8

Empire

18.0 (17.0-19.0)

3.7 (3.0-5.2)

11.2

Jonagold

17.6 (16.3-19.4)

5.6 (4.4-6.6)

13.8

Golden Delicious

17.6 (16.0-19.0)

3.5 (2.8-4.0)

12.4

Ida Red

18.0 (17.0-18.0)

1.7 (1.0-2.0)

10.5

Fuji (late season)

20.5 (19.4-22.0)

3.2 (2.4-4.4)

11.8

Individual variety results

Gala and Jonathan

No new samples were taken this week as most have been harvested in area.

Honeycrisp

The current average is 7.4 with a target mature starch index of 3.5 for this variety. The current average firmness of 14.8 is below the general guideline of 17 pounds for best long-term controlled atmosphere (CA) storage. Some of the over-mature fruit are developing an alcohol-like odor.

The predicted peak harvest date is Sept. 20 for central Berrien County. There still are quite a few Honeycrisp yet to be picked in the area, some held in check with Retain applications. This variety matured ahead of the predicted date. The fungal disease bitter rot is more prevalent this year on this variety. Watercore and bitter pit seem to be minor concerns.

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

Sept. 16

15.4 (14.0-16.2)

6.4 (4.6-8.0)

12.8

Sept. 23

14.8 (13.3-16.3)

7.4 (6.6-8.0)

13.1

Empire

Empire was sampled for the third week. Like Jonathan, this variety is generally utilized as taffy apples and as fresh apple slices. The target starch test for mature apples for apples destined for fresh market or fresh apple slices is 3.5 with a minimum firmness of 18 for long term CA storage. Predicted harvest dates for fresh market for central Berrien County is Sept. 26, which seems to be about on target with the current average firmness of 18.0 and starch average of 3.7.

Empire maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 10

19.4 (18.0-20.0)

2.2 (2.2-2.5)

11.2

Sept. 16

18.6 (17.2-20.0)

2.9 (2.0-4.0)

11.3

Sept. 24

18.0 (17.0-19.0)

3.7 (3.0-5.2)

11.2

Jonagold 

Jonagold was sampled for the third week. Starch conversion this week is averaging 5.6, with 3.5 as the target for mature for this variety. Fruit firmness this week averaged 17.6 pounds, about the same as last week, with the general guideline of a minimum of 17 pounds firmness for best long-term CA storage. The predicted peak harvest date is Sept. 30 for central Berrien County. This variety seems to be maturing slightly ahead of the predicted date. Approximately 60% of the area Jonagold have been harvested.

Jonagold maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 10

19.3 (18.0-20.0)

2.4 (2.0-3.4)

11.6

Sept. 16

17.7 (17.0-18.4)

3.8 (3.0-4.8)

12.5

Sept. 23

17.6 (16.3-19.4)

5.6 (4.4-6.6)

13.8

Golden Delicious 

Golden Delicious was sampled for the second week. Starch conversion this week is averaging 3.5, a jump over last week’s 1.6, with 3 as the target for mature for this variety. Fruit firmness this week averaged 17.6 pounds, about the same as last week and pretty close to the general guideline of a minimum of 17 pounds firmness for best long-term CA storage. The maturation of this variety is ahead of the predicted peak harvest date of Oct. 1 for central Berrien County. Starch conversion has caught up to fruit softening. Approximately 40% of the area Golden Delicious have been harvested.

Golden Delicious maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 16

17.5 (17.0-18.0)

1.6 (1.0-2.0)

11.4

Sept. 23

17.6 (16.0-19.0)

3.5 (2.8-4.0)

12.4

Red Delicious 

Red Delicious was sampled for the first time this week. Fruit at 16.0 or lower are considered appropriate for short-term CA storage and more immediate consumption, with the average for this week testing at 17.1 pounds firmness. Starch conversion is now at 3.3, with a reading of 3.5 or greater is consider sufficiently mature for harvesting. The predicted peak harvest date for Red Delicious in central Berrien County is Oct. 7. Very few of the area Red Delicious have been harvested so far.

Red Delicious maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 23

17.1 (16.0-18.1)

3.3 (3.0-4.0)

10.7

Ida Red

The current starch test average of 1.7 is well below the mature threshold of 3.5. Minimum recommended firmness for long-term CA storage is 16 pounds, currently averaging 18.0. The predicted harvest date for Ida Red in central Berrien County is Oct. 15.

Ida Red maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 23

18.0 (17.0-18.0)

1.7 (1.0-2.0)

10.5

Fuji (late season varieties)

A minimum of 3.0 for the starch index is recommended for harvesting for fresh for Fuji. Since the current firmness is testing well above 16 pounds—the recommended minimum firmness for long-term CA storage—harvest can be delayed to wait for better size, brix and skin color. The predicted harvest date for Fuji for central Berrien County is Oct. 28.

Fuji (main season) maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 23

20.5 (19.4-22.0)

3.2 (2.4-4.4)

11.8

 

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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