Grand Rapids area apple maturity report – Sept. 4, 2019

Early apple variety harvest is finishing up with Gala harvest on tap for next week.

General comments

Welcome to the first of several 2019 apple maturity reports from the Grand Rapids, Michigan, area Michigan State University fruit team. As you know, many changes in apple physiology occur over time as fruit become more mature—starch is converted to sugar; seeds turn a darker color; acidity decreases; chlorophyll levels decrease; respiration increases; cell walls weaken, fruit begins to soften; and ethylene production increases. Our MSU Ridge Apple Quality Lab and the MSU campus Beaudry Lab measure these and many other factors to help you make harvest management decisions. We are graciously funded by the Michigan Tree Fruit Commission, Michigan Apple Committee, Michigan State Horticultural Society and Michigan State University Extension. Many thanks to all the growers and industry representatives that donate to our program.

In the Grand Rapids area, apple maturity seems to be running close to our 2019 predicted apple harvest dates. We are seeing trends in maturity parameters that McIntosh might be three or four days ahead of our predicted dates and Gala perhaps a day earlier than predicted. Keep in mind these predicted dates are for peak harvest, so some fruits might be ready ahead or behind these dates as we move through maturity.


 Normal and 2019 peak harvest dates for varieties for the Grand Rapids area

Variety

Normal date

2019 predicted date

Paulared

8/24

8/30

Gingergold

8/26

9/1

Gala

9/10

9/15

McIntosh

9/15

9/20

Honeycrisp

9/18

9/23

Empire

9/24

9/30

Jonathan

9/26

10/6

Jonagold

9/26

10/6

Golden Delicious

10/2

10/8

Red Delicious

10/5

10/11

Idared

10/10

10/15

Rome

10/15

10/20

Fuji

10/25

10/28

Braeburn

10/25

10/28

Goldrush

11/1

11/3

Paula Red and Gingergold harvest is mostly completed on the Ridge with overall good quality being reported. Fruit color has been excellent due to cool nights and sunny days. After several years with poor coloring weather, it is nice to get back to “normal.” Size has been outstanding all summer and much improved from 2018. Premier Honeycrisp are also being picked as are some of the newer early strains of Gala.

Variety sampling results

Strains are noted where applicable. We try our best to collect samples from blocks untreated with harvest management products.

Gala

Color is good to very good to excellent on most Gala strains this year and continues to improve. Size is also good to excellent. With a lack of extreme hot weather in August, it is expected that traditional Gala strains will not be earlier in their maturity by more than a day ahead of our predicted harvest date of Sept. 15. Early Gala cultivars (Wildfire, Foxtrot) are being spot picked as needed now. Some with Fulford Gala and known early sites might be ready very soon. I separated the data from early vs. normal Gala strains in the two tables below.

Early Gala (Foxtrot, Wildfire) 2019 maturity sampling records

Date of sample

Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch range)

Brix (range)

Aug. 21

NA

NA

79 (65-92)

3.6 (3-5)

21.2

4.8 (2-7)

12.0 (10.6-13.5)

Aug. 27

NA

NA

73 (45-95)

2.9 (1-5)

19.8

4.6 (1-7)

12.2 (10.8-14.4)

Sept. 3

NA

NA

92 (75-100)

1

18.4

6.8 (2-8)

12.4 (12-12.6)

 

Traditional Gala (Gale, Buckeye) 2019 maturity sampling records

Date of sample

Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch range)

Brix (range)

Aug. 21

NA

NA

49.3 (35-70)

4.8 (3-5)

23.7

1.8 (1-5)

10.8 (10-13.8)

Sept. 3

NA

NA

68.3 (45-90)

3.8 (3-5)

25.6

1.4 (1-3)

11.5 (10.4-12.8)

McIntosh

McIntosh seem to be maturing a bit faster than the predicted harvest date of Sept. 20 indicates—we think Macs might come into peak harvest about three or four days ahead, but another week of sampling will narrow that in. They are definitely immature at this time.

McIntosh (RubyMac) 2018 maturity sampling records (Linda Mac)

Date of sample

Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Sept. 3

NA

NA

73 (60-90)

5

17.5

NA

12.3 (11.6-13.2)

Honeycrisp

Premier Honeycrisp are on their second week for spot picking; they are starting to drop already. Watch your regular Honeycrisp closely as they seem to be showing great color and might need some early picking to stay ahead of drop if it happens like in the Premiers. Our predicted date for traditional Honeycrisp is Sept. 23 for peak harvest.

Premier Honeycrisp 2019 maturity sampling records

Date of sample

Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Aug. 21

NA

NA

40 (20-60)

4.3 (3-5)

15.6

4 (2-6)

12.6 (12-13.8)

Aug. 27

NA

NA

52 (35-70)

3.7 (2-5)

13.8

5.3 (3-7)

13.4 (12.6-14.2)

 

Honeycrisp (Firestorm) 2019 maturity sampling records

Date of sample

Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Red color % (range)

Background color (range)

Average Firmness lbs pressure

Starch (range)

Brix (range)

Aug. 28

NA

NA

26 (5-80)

4.7 (3-5)

18

1.7 (1-7)

12.8 (12.2-14.2)

Apple maturity sampling parameters

  • % fruits with internal ethylene over 0.2 ppm = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
  • Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested
  • Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
  • Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
  • Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
  • Brix = % sugar measured with Atago PAL-1 Pocket Refractometer
 


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