Northwest Michigan apple maturity report – Sept. 30, 2020

Growers are ramping up harvest as Gala and McIntosh varieties are ripening; growers are also spot picking Honeycrisp.

General apple harvest comments

Apple harvest is underway in northwest Michigan at this time. Boxes have been moved into orchards, and growers are going after Gala and McIntosh at this time. Growers have been eager to get into the orchard for a few weeks, so now that harvest has really started in earnest, growers are feeling relieved. 

The previous week’s weather has certainly been favorable for apples. We had sunny days and cool temperatures, and as a result, fruit color is excellent on many varieties. Some growers are still waiting on color, especially in blocks of Honeycrisp and older strains of McIntosh. We have seen growers employ reflective materials in the orchard this season in hopes of achieving optimal color on fruit. Last week, daytime temperatures were in the mid-50s degree F, and nighttime temperatures fell into the 40s degrees F. Growers were concerned about overnight temperatures last Friday and Saturday (18 and 19 September). The overnight lows recorded at the NWMHRC Enviroweather station were 41.4 degrees F and 37.1 degrees F, respectively. However, in some low spots in the region, frost was reported, and many sensitive garden plants were impacted. Most fruit sites were spared of below freezing temperatures. Thus far this season, we have accumulated 3396 GDD base 42 and 2258 GDD base 50. Temperatures are predicted to be warm until next Tuesday, and the weather will be pleasant (maybe a bit on the warm side) for harvest for the remainder of the week and into the weekend. 

As mentioned previously, growers have been pleased with apple quality at this time of the season. Overall, firmness seems to be holding. Firmness did drop in McIntosh, which is to be expected in this variety. In some blocks, we have also observed McIntosh pushing off the trees. Many growers are harvesting McIntosh and Gala at this time. Gala seem to be further ahead of McIntosh this year, likely due to the warm conditions through the growing season. McIntosh have some variability in ripeness which can be contributed to the many different strains, older and newer, strains of McIntosh. Color has also been variable in Macs. 

Growers are also harvesting Gala, and we harvested our two blocks of Gala at the NWMHRC on Monday, 21 September. Color on Gala at the NWMHRC was excellent, and fruit are still firm and tasty. Growers are also starting Honeycrisp harvest in many warmer areas of the region. Honeycrisp firmness is also still good, and Brix is increasing. Some growers are waiting on color and Brix before they harvest. 

We caught five brown marmorated stink bug (BMSB) at the NWMHRC this week, four adult males and one nymph. This is the highest catch of BMSB in a trap at the NWMHRC that we have found since we started trapping for this pest a few years ago. We did not catch BMSB at two grower sites in Leelanau County, but we have started to observe adults on houses in the area. 

We have observed unusually high bird peck damage in orchards this season. These bird pecks are high in the tree, but also on the ground, which are turkeys pecking from ground level. Fruit flies are on the rise with the warm temperatures; this pest is not a problem in undamaged apples, but they are in high populations in houses.

Apple maturity in northwest Michigan for apples collected on Sept. 22, 2020

Variety

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

McIntosh

90% (75 - 100)

17.3 (14.5 - 22.5)

3.8 (2 - 6)

11.9 (11 - 13.9)

Honeycrisp

74.3% (50 - 95)

18 (15 - 22)

2.7 (1.5 - 5)

11.6 (10.1 - 13.7)

Gala

95% (90 - 100)

21.4 (17.5 - 23)

1.4 (1 - 3)

11.6 (10.1 - 13.5)

Jonagold

93%

19

2.2

12.8

Macoun

83%

19

1

11.3

Ida Red

82%

21.8

1.1

11.4

 

McIntosh maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 1, 2020

83% (60-100)

18.9 (16-22)

1.1 (1-1.5)

10.25 (9.6-11)

Sept. 8, 2020

88% (60-100)

18.7 (14-23)

1.8 (1-4)

11.1 (9-12)

Sept. 15, 2020

81% (40-100)

17.2 (14.5-20.5)

3 (1-6)

11.5 (10.8-13)

Sept. 22, 2020

90% (75 - 100)

17.3 (14.5 - 22.5)

3.8 (2 - 6)

11.9 (11 - 13.9)

McIntosh harvest is underway and three blocks were sampled this week. Color is lovely on these apples and firmness is holding. Starch indices indicate that these apples are ready to pick, especially for storage. Overall, Brix are increasing, and some of the apples sampled were at nearly 14 degrees Brix this week.

Honeycrisp maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 1, 2020

41.3% (15-70)

19.2 (16-23)

1 (1-1.5)

10.0 (8.6-10.8)

Sept. 8, 2020

51% (5-95)

18.6 (16-22)

1.2 (1-2)

10.4 (8.8-11.4)

Sept. 15, 2020

72.3% (50-95)

18.4 (15-22)

2 (1-4)

11 (9.8-12.6)

Sept. 22, 2020

74.3% (50 - 95)

18 (15 - 22)

2.7 (1.5 - 5) 

11.6 (10.1 - 13.7)

We sampled ten Honeycrisp blocks this week, and parameters are moving in the right direction. As is typical with Honeycrisp, apple maturity is variable in blocks with some apples, and growers are spot picking. 

Gala maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 8, 2020

82% (20-100)

21.3 (17-23)

1.9 (1-7)

11.2 (9-14.6)

Sept. 15, 2020

88% (60-100)

21.2 (17.5-23)

1.5 (1-4)

11.3 10-13)

Sept. 22, 2020

95% (90 - 100)

21.4 (17.5 - 23)

1.4 (1 - 3)

11.6 (10.1 - 13.5)

Two blocks of Gala were tested this week and Gala harvest is underway. Gala are firm and starch readings in the two blocks that were sampled are variable with some apples testing more mature than others. Color is excellent and Brix readings are approaching 14 degrees. We have continued to hear positive comments on Gala size this season.

Jonagold maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 15, 2020

90%

19.2

1.8

11.2

Sept. 22, 2020

93%

19

2.2

12.8

For the second consecutive week, one sample of Red Jonagold was tested. Color is improving as well as starch indices and Brix. The apples are firm, and not quite ready for fresh eating.

Macoun maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 22, 2020

83%

19

1

11.3

One sample of Macoun was tested and parameters indicate that this variety is not yet ready for harvest.

Ida Red maturity sampling for the harvest season

Sample date

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 22, 2020

82%

21.8

1.1

11.4

One sample of Ida Red was tested, and parameters indicate that this variety is not yet ready for harvest.

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.

Did you find this article useful?


You Might Also Be Interested In