West central Michigan apple maturity report – Aug. 29, 2018

Updates on maturity status for commercial varieties in west central Michigan.

General harvest comments

Harvest of several early varieties including Ginger Gold and Paulared is either ongoing or complete at this time. SweeTango harvest has begun in Elbridge, Michigan, and this variety will likely be picked in Hart, Michigan, as the week goes on. Growers are eyeing Gala and are eager to get going on it as soon as possible, but the variety still has a few days to go before it hits target maturity marks for controlled atmosphere (CA) storage. Honeycrisp harvest is still a good two weeks out in the area.

Rain is on the forefront of everyone’s mind right now; I don’t think most of us have been properly dry in about a week at this point. Accumulations around the area have been pretty staggering, the Hart Enviroweather station has recorded over 4 inches of total rainfall in the past week and other areas are reporting at least this much if not more. This much rain in close proximity to harvest can increase incidence of watercore, and can also increase incidence of bitterpit if the rain causes a major increase in fruit size. Watercore and bitterpit prone varieties like Honeycrisp still looked fine in our maturity tests this week, but we will monitor the situation over the next few days as more tests are taken.

Despite the rain and some strong storms over the past week, the crop in the area looks generally good and no major storm damage has been reported in the region, although fruit size tends to be small in many locations. Fresh market acreage that has been irrigated this season generally seems to be doing well, but there is some pretty small fruit out there in processing blocks bearing a heavier crop. The upside to the recent rains is they should help with size somewhat, and there are quite a few processing varieties that are in serious need of some extra sizing in the next few weeks in order to catch up.

The scales used to rate these different metrics on these charts are as follows:

  • Background color: scale 1-4; 1 is fully yellow and 4 is fully green.
  • Russet: scale 1-4; 1 is no russet and 4 is severe russet.
  • Pressure: always listed in pounds per square inch, and two pressure scores are recorded for each apple tested.
  • Watercore: scale 1-4; 1 is no watercore and 4 is severe watercore.
  • Bleeding: scale 0-4; 0 is no bleeding of red color into flesh and 4 is severe bleeding of red color in to flesh.
  • Red: listed as a percentage of the whole fruit with red color.

Individual variety results

Ginger Gold jumped up from a starch index of 1.2 last week to 2.4 this week. Ripening is occurring rapidly at this point, most growers who haven’t gotten after Ginger Gold will do so at some time this week. They are eating nicely at this point in spite of a low starch index score. Some light brown marmorated stink bug damage was observed at this site this week.

Regional summary data for Ginger Gold, west central Michigan 2018

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 20

23.06 (19.5-30)

1.2 (1-3)

14.01 (13-15)

Aug. 27

18.09 (10-23)

2.4 (2-4)

13.54 (12-14.5)

Ginger Gold, Ludington areaGG-Ludington

McIntosh starch index values are moving along compared to last week, but most of the fruits tested this week were still pretty starchy. Optimal harvest for CA is still a few days out at most locations, fruit need some time to hit the starch index target of 5. This variety is on the small side this year. Trees with a heavy crop on sandy sites are particularly little.

Regional summary data for McIntosh, west central Michigan 2018

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 20

19.5 (18-24)

2.33 (1-3)

11.1 (9-13)

Aug. 27

16.2 (14-19)

2.45 (1-4)

11.2 (10-14)

McIntosh, Hart area
McIntosh Hart

McIntosh, Clay-Banks area
McIntosh Clay Banks

McIntosh, Ludington area
McIntosh Luding

McIntosh, New Era area
McIntosh New Era

Gala continues to look very nice at most locations, but don’t let appearances fool you – this variety needs more time, fruits are still very starchy. Size is on the small size at some locations, but for many growers this is not a bad thing for Gala.

Regional summary data for Gala, west central Michigan 2018

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 20

25.5 (22-29)

1.05 (1-2)

10.75 (9-12)

Aug. 27

23 (19-30)

1.7 (1-4)

11.6 (10-13)

Pacific Gala, Benona area
Pacific Gala  Benona area

Buckeye Gala, Hart area
Buckeye Gala Hart area

Pacific Gala, Hart area
Pacific Gala Hart area

Brookfield Gala, Mears area
Brookfield Gala Mears area

Un-named Gala strain, Ludington area
Un-named Gala strain Ludington area

Twin Bee strain, Ludington area
Twin Bee strain Ludington area

Pacific Gala, Elbridge area
Pacific Gala Elbridge area

Pacific Gala, Weare township area
Pacific Gala Weare township area

Early Fuji is still pretty small and poorly colored at the two sites that are being sampled from. The variety has a way to go before harvest yet, and growers will be hoping for some more size and color prior to harvest.

Regional summary data for Early Fuji, west central Michigan 2018

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 20

20.5 (19-23)

1.35 (1-2)

10.75 (9-11.5)

Aug. 27

18 (16-23)

1.85 (1-4)

11.45 (9.5-12)

Early Fuji, Ludington area (site 1 of 2)
Early Fuji Ludington area (site 1 of 2)

Early Fuji, Ludington area (site 2 of 2)
Early Fuji Ludington area (site 2 of 2)

Honeycrisp was sampled for the first time this week. We are at least two weeks from harvest in the area, they are still very green and starchy. Generally, the crop looks pretty good, although we do have some small fruit and size variability in the crop load within blocks. Variability in crop quantity and size within orchards has been something that has been observable since the big heat wave over the Memorial Day weekend. The amount of fruit that fell off trees in response to that heat was significant and caused many growers to pass on chemically thinning Honeycrisp this year. These factors taken together resulted in a crop with quite a bit of variability, even within a single location.

Despite the significant rainfall over the past week, incidence of watercore and bitterpit generally was very low in samples that were taken this week.

Regional summary data for Honeycrisp, west central Michigan 2018

Sample date

Firmness lbs. (range)

Starch index (range)

Brix % (range)

Aug. 27

16.8 (15-21)

1.3 (1-3)

11.4 (10-12.5)

Honeycrisp, Elbridge area
Honeycrisp Elbridge area

Honeycrisp, Weare township area
Honeycrisp Weare township area

Honeycrisp, Ludington area (site 1 of 2)
Honeycrisp Ludington area (site 1 of 2)

Honeycrisp, Hart area
Honeycrisp Hart area

Honeycrisp, Clay Banks area
Honeycrisp Clay Banks area

Honeycrisp, Mears area
Honeycrisp Mears area

Honeycrisp, Ludington area (site 2 of 2)
Honeycrisp Ludington area (site 2 of 2)

I have included the table for optimal firmness and starch index for the major commercial varieties in our area in the table below. It’s always a good idea to take some time to refresh on your targets each season based on intended duration of CA storage for the variety in question.

Optimal fruit firmness and starch index for various lengths of CA storage

 

Variety

Firmness (pounds)

Starch 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

 


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