Northwest Michigan apple maturity report – Oct. 3, 2018

Gala harvest is underway and cool, wet weather has posed some harvest challenges. Apple quality remains good.

Apple picking platform
The N. Blosi platform was used to pick apples from the tops of the high density apples. Photo by Jennifer Zelinski, MSU Extension.

General apple harvest comments

This is the sixth 2018 apple maturity report from northwest Michigan, and these data show that Jonagold apples are in the mature range according to starch indices. Gala harvest is underway and many McIntosh blocks have been picked for the processing market. Last week, our McIntosh samples still were testing on the green side, but three blocks we tested last week were gone this week.

Honeycrisp harvest is winding down and many growers expect to finish this week. Honeycrisp fruit is still looking good, but we have observed more bitter pit showing up in stored fruit that we harvested at the Northwest Michigan Horticulture Research Center in the last two weeks. Growers are picking all varieties that are close to mature based on requests from processors. Fruit quality is still holding, and color continues to improve the longer the fruit hangs on the tree.

Recent wet weather has posed some harvest challenges. The Northwest Michigan Horticulture Research Center Enviroweather station has recorded multiple rainfall events in the past week. We had four days of minimal rain from Sept. 25-28: 0.12 inch, 0.05 inch, 0.12 inch and 0.14 inch. Saturday and Sunday (Sept. 29-30) were dry, and on Monday, Oct. 1, the station recorded 0.82 inch of rainfall. On this Tuesday morning, we have received just under 0.5 inch of rain, and the rain is expected to last throughout the day.

We have had reports of minor flooding near newly planted orchards, particularly in areas that are planted on slopes. Day- and nighttime temperatures are cool, which would be good conditions for picking apples except for the continued rains. Other than the soggy conditions, growers remain optimistic about the 2018 apple crop and harvest.

Honeycrisp apples
Apple bin full of Honeycrisp apples from the high density plot at the Northwest Michigan Horticulture Research Station. Photo by Jennifer Zelinski, MSU Extension.

Apple maturity in northwest Michigan for apple collected on Oct. 2

Variety

Firmness lbs. (range)

Starch (range)

Brix

Color %

Gala

18.5

2.5

12.4

89

Jonagold

15.1 (12.9-16.4)

3.4 (3.0-4.1)

14.3

77

Individual apple variety results

Two of the three Gala blocks that we sample for apple maturity have been harvested. Gala from the remaining blocks are approaching the suggested firmness and starch index levels for Gala that will be stored. Color on Gala has continued to improve with the cool weather and size has also improved in the past two weeks. Earlier in the season, some growers were concerned about small size in Gala, but in the last two samples, fruit size is looking good.

Gala maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Aug. 27

22.65 (22.6-22.7)

1.0

9.85

39.2

Sept. 4

21.6 (21.3-21.9)

1.03 (1.0-1.05)

10.15

54

Sept. 11

20.2 (20.1-20.3)

1 (1.0-1.0)

10.95

78

Sept. 18

20.2 (20.1-20.3)

1.1 (1.1-1.1)

11.5

89

Sept. 25

18.65 (18.5-18.9)

1.6 (1.45-1.85)

12.7

87

Oct. 2

18.5

2.5

12.4

89

We sampled three Jonagold blocks this week and results indicate this variety is mature. Most of the apples we sampled remain firm and brix are improving. However, there is variability in firmness across blocks. Jonagold color is decent but could be improved. Growers are letting this variety hang in hopes to increase red color. Brix levels remain steady from last week.

Jonagold maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Sept. 25

17.3 (17.08-17.4)

2.4 (2.25-2.55)

13.3

74

Oct. 2

15.1 (12.9-16.4)

3.4 (3.0-4.1)

14.3

77

We tested one sample of JonaPrince Jonagold and these apples are very firm with good brix and excellent color. Starch levels indicate these apples should be harvested soon.

JonaPrince Jonagold maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Oct. 2

19.4

3.1

14.1

100

 

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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