Southwest Michigan apple maturity report – Sept. 13, 2017

Gala and Honeycrisp picking are still underway. Apple internal ripeness is moving rapidly.

General apple harvest comments

Recent rains will help sizing of later ripening fruit. Some new oriental fruit moth larvae entries have been seen in area fruit. Brown marmorated stink bug adults are becoming easier to find in area orchards, but still are generally at low levels.

Data in the following table is 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 Sep. 11

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Gala

19.8 (22.0-18.3)

5.1 (6.6-3.2)

14.0

Honeycrisp

14.1 (15.0-13.1)

6.9 (8.0-5.4)

13.6

Jonagold

15.9 (16.3-15.0)

6.3 (8.0-4.4)

12.2

Jonathan

17.2 (19.3-16.0)

4.0 (4.3-3.0)

13.1

Empire

17.0 (19.0-16.4)

3.9 (4.4-2.4)

13.0

Golden Delicious

17.2 (21.0-15.2)

3.6 (6.6-1.0)

12.7

Individual variety results

Gala harvest is winding down in the area. Fruit firmness has apparently stabilized, with the average still above the long-term controlled atmosphere (CA) storage minimum of 18 pounds. This may be an artifact of sampling—several orchards that tested low pressure last week have been harvested and are not included in this week’s average.

All blocks tested have starch conversion readings testing internally mature (3 or above) with the overall average of 5.1. Flavor and color have been generally very good. Some fruit are developing a waxy feel. The predicted harvest date for peak harvest for southwest Michigan in 2017 is Aug. 25, which appears to be generally on target.

Honeycrisp maturity is moving steadily, with starch conversion averaging 6.9, compared to 5.7 for last week, well above the target starch index of 3.5 or above recommended for good storage. Firmness this week averaged 14.1, slightly below last week’s average of 14.4 pounds, with all sites tested below the ideal 16 for mid-term CA storage.

As is the case with Honeycrisp, there is a wide of ripening and some pre-harvest drop. Maturity is slightly ahead of the predicted peak harvest date of Sept. 4 for central Berrien County for 2017, quite a bit ahead of the normal date of Sept. 15.

Skin blush ranged from 40 to 70 percent for standard Honeycrisp, with generally less bitter pit than normal, probably due to dry conditions. Precondition Honeycrisp fruit between 50 and 68 degrees Fahrenheit for five to seven days before refrigeration to help avoid storage disorder problems.

Jonagold reached internal maturity for many orchards last week ahead of the target harvest date for central Berrien County of Sept. 15. This week’s average starch index is 6.3, compared to 5.2 last week and 3.2 for the week before. The target starch index for fruit destined for fresh market is at least 3.5.

Current firmness of 15.9 pounds is about 0.5 less than last week, and is in the recommended mid-term CA storage window range. As is typical for this variety, internal maturity has moved rapidly.

Jonathan maturity is moving steadily with firmness of 17.2 pounds, still above the borderline of 16 between long and mid-term CA storage. The current starch test is averaging 4.0, above the 3.5 point that is considered mature for successful CA storage. Firmness is averaging 17.9 pounds, still above the borderline of 16 pounds between long and mid-term CA storage.

Approximately half of the area Jonathan blocks have been picked. The predicted peak harvest date for central Berrien County is Sept. 15, which seems to be about right.

Empire starch conversion reading this week is averaging 3.9, above the 3.5 point that is considered mature, and a significant step above last week’s value of 2.1. Fruit firmness averages have held at an average of 17 pounds.

The predicted peak harvest date is Sept. 10 for fresh market for central Berrien County, which matches what we are seeing in the field. Growers have been holding off harvesting Empires in the area. Brix is averaging 13, slightly higher than last week.

Golden Delicious were tested for the second time with firmness this week averaging 17.2 pounds, about 1.5 pounds below last week. Starch conversion has moved along with this week’s average of 3.6, compared to 1.4 for last week. Brix has not moved much with this week’s 12.7 the same as last week.

No new harvesting of Golden Delicious were noticed since last week. Golden Delicious are showing significant blush of 5 to 30 percent orange/pink on green background.

Predicted peak fresh market apple harvest dates

The normal and estimated 2017 peak harvest dates for apple varieties in southwest Michigan table is included here, as general guidelines. Predicted harvest dates for early season apple varieties are 10 to 15 days ahead of normal due to warm temperatures in the month following bloom. Light crop and earlier dry conditions have also advanced maturity. 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 2017 peak harvest dates for apple varieties in southwest Michigan based on SWMREC weather data.

Variety

Normal date

2017 predicted date

Paula Red

Aug. 22

Aug. 7

Zestar

Aug. 22

Aug. 7

Gingergold

Aug. 20

Aug. 9

McIntosh

Sept. 10

Aug. 29

Gala

Sept. 8

Aug. 25

Early Fuji

Sept. 3

Aug. 24

Honeycrisp

Sept. 13

Sept. 4

Empire

Sept. 19

Sept. 10

Jonathan

Sept. 22

Sept. 15

Jonagold

Sept. 22

Sept. 15

Golden Delicious

Sept. 25

Sept. 19

Red Delicious

Sept. 28

Sept. 22

Ida Red

Oct. 5

Sept. 30

Rome

Oct. 5

Sept. 30

Fuji

Oct. 20

Oct. 15

Braeburn

Oct. 20

Oct. 15

Goldrush

Oct. 26

Oct. 21

 

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.)

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.

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