Southwest Michigan apple maturity report – October 2, 2013

Golden Delicious and some Red Delicious harvesting are underway in southwest Michigan. Recent dry conditions have helped harvest go relatively fast with excellent fruit quality.

General comments

Insect and disease problems are relatively minor on apples with the exception of some late season San Jose scale. Marmorated stink bug activity in a few areas has increased as adults are starting to move to find overwintering sites. None yet reported in fruit crops.

Summary of Berrien County apple maturity samples taken Sept. 30, 2013

Variety

Date sampled

Firmness lb. pressure (range)

Starch conversion (range)

Brix (range)

Golden Delicious

Sept. 30

15.8 (16.8 - 15.0)

5.0 (3.0 – 6.4)

14.0 (12.8 - 14.7)

Red Delicious

 

Sept. 30

17.2 (18.5 - 16.5)

2.9 (2.0 – 4.0)

11.6 (10.9 - 12.1)

Fuji

Sept. 30

18.6 (17.7 - 19.2)

3.8 (2.8 - 5.2)

13.3 (12.7 - 14.4)

Ida Red

Sept. 30

16.5 (16.6 - 16.4)

2.6 (2.2 - 3.0)

12.5 (12.3 - 12.7)

Golden Delicious (six sites sampled Sept. 30)

Some area growers have been harvesting this variety in order to get the fruit off before more blush develops as some markets require non-blushed fruit. Readings this week are firmness 15.8 pounds (15-16.8) compared to 16.4 pounds for last week, starch conversion 5 (3-6.4) compared to 2.9 for last week, and brix of 14 (12.8-14.7) compared to 13.8 last week. For this variety, the target fruit conditions for long-term CA storage is 17 pounds firmness or greater and minimum of 3 on the starch conversion scale. Predicted harvest date for central Berrien County was Sept. 25, 2013. All six blocks tested had the more advanced fruit with starch conversion in the mature range with firmness generally suitable for mid-range duration for CA storage.

Red Delicious (six sites sampled Sept. 30)

This week’s tests show firmness of 17.2 (range 18.5-16.5) with 17.8 pounds for last week, starch conversion 2.9 (range 2-4) with 2.4 last week, and brix 11.6 with 10.9 for last week. Predicted harvest date for central Berrien County is Oct. 3, 2013. For this variety, the target fruit conditions for long-term CA is fruit firmness of 18 pounds or greater and minimum of 2.5 for the starch conversion index. Five of six sites tested had the more advanced fruit in the orchards testing starch conversion in the mature category with firmness adequate for midrange duration CA storage.

Fuji (five sites sampled Sept.30)

This week’s tests show firmness of 18.6 (range 17.7-19.2), about 1 pound less than 19.4 for last week, starch conversion 3.8 (range 2.8-5.2) with 3.5 last week, and brix 13.3 compared to 12.5 last week. For this variety, the target fruit conditions for long-term CA are fruit firmness of 17 or greater and minimum of 3 for the starch conversion index. Predicted harvest date for central Berrien County is Oct. 20, 2013. Fruit quality is improving. The continued excellent firmness will allow delay of harvest until skin color, size and brix improves, although starch conversion is sufficient in some sites for harvest. Fruit that are clustered or in shaded areas of the tree are considerably less mature.

Ida Red (two sites sampled Sept. 30)

This week’s tests show firmness of 16.5 (range 16.4-16.6), about 1 pound lower than last week, starch conversion 2.6 (range 2.2-3.) compared to 1.7 for last week, and brix 12.5 compared to 11.7 for last week. Predicted harvest date for central Berrien County is Oct. 5, 2013. For this variety, the target fruit conditions for long-term CA are fruit firmness of 15 pounds or greater and minimum of 3.5 for the starch conversion index. Harvest of orchards similar to these samples can be delayed to wait for better size and greater starch conversion.

Pressure and starch conversion target indices for apple maturity for selected varieties

Variety

Firmness

Starch

Short CA*

Mid-CA

Long CA

Mature

Over mature

Golden Delicious

15

16

17

3.0

6.5

Red Delicious

16

17

18

2.5

5.0

Fuji (main season)

15

16

17

3.0

7.0

Ida Red

14

15

16

3.5

6

*CA = controlled atmosphere storage

The Southwest Michigan Apple Maturity Report is produced by: Bill Shane, MSU district Extension educator for fruit and marketing, Benton Harbor, 269-944-1477 ext. 205, fax 269-944-310; Diane Brown, Berrien County Extension educator, Benton Harbor, 269-944-4126; and Mark Longstroth, district Extension educator for fruit and marketing, Paw Paw.

Looking for more? View Michigan State University Extension’s Apple Maturity Program and Reports resource page for regional reports throughout the state and additional resources.

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