West central Michigan apple maturity report – Sept. 20, 2017

Gala harvest is ending at many sites. Honeycrisp are being picked and will dominate the harvest in the next several days. Growers are concerned about high temperatures forecasted for the next several days.

General harvest comments

Harvest of Gala is winding down at many sites, and growers that have yet to pick this variety are getting ready to hit it hard. Remaining Galas at many sites are becoming over-mature, so the rush is on to get them off the trees and into storage. First picking of Honeycrisp is in full swing. Growers are starting to eye Jonathan, Mutsu/Crispin, Golden Delicious and Empire at many sites. All of these cultivars will be harvested to some degree within the week at many earlier sites. In general, we seem to be running on the early side this year.

We are currently experiencing higher than normal temperatures in the region. This is expected to continue for several days, with temperatures as high as 85 degrees Fahrenheit forecasted for some parts of west central Michigan later in the week. These higher temperatures have growers concerned about fruit finish and storage issues. Read “Hot, hot apple harvest concerns” by Michigan State University Extension for considerations when handling hot fruit going in a storage situation.

Brown marmorated stink bugs are still very low in the area, though they have been detected in small numbers elsewhere in the state. They are particularly common in other areas on Golden Delicious, so keep a close eye on this variety in coming days. Our brown marmorated stink bug traps in west central Michigan did not catch any adults or nymphs in the past seven days. Second generation of codling moth is over, and trap counts have dropped down to zero in most blocks. We are not expecting a third generation.

The normal and estimated 2017 peak harvest dates for apple varieties in Grand Rapids, Michigan, is included at the end of this report. While we have historically assumed we lag behind the Ridge in the west central region, this does not seem to be so much the case this season in many areas. Generally, growers in the Elbridge, Hart and Shelby areas are tracking consistently with Ridge harvest predictions, while growers near the lake in the Clay Banks and Ludington area are generally about three to five days behind. Data in the following tables are based on samples collected from commercial orchards in Oceana and Mason counties. Firmness and starch ranges are the observed as low and high mean values. Optimum long-term storage parameters are also included at the end of the article.

Individual variety results

Early Fuji was tested for the fourth time this week. The starch index recommendation for controlled atmosphere (CA) storage for this cultivars is 3, and fruits this week tested well over that mark. Fruits with a starch index of 7 or higher are considered over-mature, so fruits are still well below that mark. Harvest will likely be winding down later this week. Firmness has been holding fairly steady over the past three weeks, and color is generally good.

Early Fuji maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix %

Aug. 25

18.12 (15.5-25)

2.2 (1-4)

12 (10.5-14.5)

Sept. 6

15.25 (11-18.5)

3.2 (1-6)

12.25 (11-14)

Sept. 13

14.98 (11-15.5)

3.2 (2-7)

12.42 (11-13)

Sept. 20

15.28 (12-19)

4.8 (3-8)

13.86 (12-15)

Honeycrisp was sampled for the fifth time this week. Target starch index for this variety for long-term CA storage is 3.5. Starch indices for the west central region are now consistently above this mark, so Honeycrisp can be considered mature at most sites. Color on Honeycrisp is outstanding this season, and firmness still seems to be holding.

Growers further south on the Ridge have noticed significant increases in lenticel breakdown over the past several days. This may show up with the heat here in west central Michigan over the next several days. Water core is very minimal this season. Bitter pit is common in sites bearing a light crop due to spring frost, but this disorder is not common in blocks bearing a full crop.

Honeycrisp maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 25

18.86 (14-22)

1.33 (1-3)

11 (19.5 - 13.5)

Sept. 6

16.15 (11.5-19.5)

2.71 (1-6)

11.7 (10-15)

Sept. 13

14.85 (11-19)

3.5 (2-6)

12.06 (9-14)

Sept. 20

15.20 (11-19)

6 (3-7)

13.48 (11-16)

Gala was sampled for the fifth time this week. Gala is now past the 3.0 starch index mark for long-term CA storage and is approaching over-maturity in some places, though firmness is still holding steady from week to week. Much of the Gala in the region is already harvested. Color and size are excellent on this cultivar this season.

Gala maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 25

22.14 (18-24)

1.3 (1-4)

11.5 (10.5-14.5)

Sept. 6

19.612 (16-24.5)

2.49 (1-6)

11.74 (10-13.5)

Sept. 13

18.79 (15.5-23.5)

3.13 (1-6)

12.60 (10-15)

Sept. 20

18.76 (15-21)

4 (2-7)

12.87 (11-14)

Jonagold was sampled for the third time this week. This variety took a big leap forward over the past seven days. The target starch index rating for long-term CA storage is 3.5, so Jonagold is ready for long-term storage throughout much of the region. Jonagold is considered over-ripe for long-term CA storage at a starch index of 5.5, so we are in the peak window of harvest. Color is excellent on Jonagold this season.

Jonagold maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 6

18.51 (16.5-20)

2.83 (1-4)

11.81 (9.5-14)

Sept. 13

17.93 (15.5-19.5)

3.7 (2-4)

12.08 (11-15)

Sept. 20

16.64 (14-19.5)

4.7 (3-7)

13.57 (10-15.5)

Jonathan was also tested for the third time this week and they are ready to go. Like Jonagold, this cultivar took a huge leap forward over the past several days. The starch index target for long-term CA storage is 3.5, and Jonathan tested well above that mark this week. Firmness also took a significant drop and brix showed a nice increase. Color on Jonathan is outstanding this year, but some red bleeding into the cortex was observed this week on the redder strains.

Jonathan maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 6

17.55 (15.5-20)

3 (3)

11.34 (10.5-12.5)

Sept. 13

17.89 (16-22)

2.85 (2-3)

13.04 (11.5-15)

Sept. 20

16.16 (14-19)

4.65 (3-6)

13.5 (13-17)

Empire was sampled for the third time this week. Size has much improved in this variety over the past two weeks, as has color. Firmness continues to be good and has held fairly steady over the past three weeks. Empire averaged just below the 3.5 starch index mark for long-term CA storage, so it has another week to go at many sites. However, a couple of early sites had average indices as high as 4.8, so some early Empire harvest may take place later this week.

Empire maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 6

18.25

2.2

10.39

Sept. 13

18.49 (14-23.5)

2.6 (1-3)

11.93 (10.5-13)

Sept. 20

17.8 (13-20.5)

3.3 (2-5)

12.69 (12.5-15)

Golden Delicious was sampled for the second time this week. This variety surprised me this week with a big move forward in maturity over the past several days. Golden Delicious has climbed above the necessary starch index of 3 for long-term CA storage at sites throughout the region. Our predicted harvest date for this cultivar is not until Oct. 1, but many sites will be harvested well ahead of that mark this year. Brix also made a nice increase over the past several days in this variety.

Red blushing is continuing to be evident in most blocks. Unfortunately, weather for coloring this year has been so good that a portion of most Golden Delicious fields have 5-10 percent red blush, so this may be an issue for growers and processors this year. There is not really anything that can be done about the blush except harvesting a hair earlier than usual to avoid any further color development.

Golden Delicious maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 13

18.07 (15.521.5)

2.4 (2-4)

11.9 (10-13)

Sept. 20

17.26 (12.5-21)

3.46 (2-6)

13.3 (10.5-14.5)

Red Delicious was sampled for the first time this week. This variety still has at least two weeks to go before maturity at most locations. Color on Red Delicious is particularly nice this year. Picking based on appearance is not wise in this cultivar right now, as color is so rich that many blocks look ripe but are still testing at around a 2 in starch index rating. They are still eating like they are all starch, no sugar.

Red Delicious maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 20

17.04 (15-22)

2.18 (2-3)

11.28 (10.5-13)

Idared was also sampled for the first time this week. Harvest of this cultivar is also about two weeks off at most locations. Fruits from all three Idared locations I sampled this week tested at a starch index of 2. Color on Idared is nice this year, most have at least 50 percent red blush already.

Idared maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Sept. 20

17.46 (16-23)

2 (2)

11.29 (9.5-13)

 

Predicted harvest dates for Grand Rapids, MI

Variety

Normal date

2017 predicted date

Paulared

Aug. 24

Aug. 19

Gingergold

Aug. 26

Aug. 21

Gala

Sept. 10

Sept. 5

McIntosh

Sept. 15

Sept. 5

Honeycrisp

Sept. 18

Sept. 15

Empire

Sept. 26

Sept. 25

Jonathan

Sept. 28

Sept. 27

Jonagold

Sept. 28

Sept. 27

Golden Delicious

Oct. 2

Oct. 1

Red Delicious

Oct. 5

Oct. 4

Idared

Oct. 10

Oct. 9

Rome

Oct. 15

Oct. 14

Fuji

Oct. 25

Oct. 24

Braeburn

Oct. 25

Oct. 24

Goldrush

Nov. 1

Oct. 31

Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety

Variety

Firmness (pounds)

Start Index

Short CA

Medium 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

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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