Southwest Michigan apple maturity report – September 25, 2013

Warm days and cool nights are helping apples mature, while dry weather is allowing farm crews to make good progress harvesting the large area crop.

General comments

The last of Honeycrisp and Gala are being harvested in the area and the few Jonagold in the area are being spot-picked for better color fruit. Some Golden Delicious blocks are being harvested for processing. There have been some complaints of red spots on fruit due to San Jose scale. Significant numbers (more than 60) of marmorated stink bugs have been found recently in a Berrien County soybean field in the Stevensville area. None of these pests have yet been reported in fruit crops, but damage is more likely as soybean fields start to mature and become less attractive to the beetles. Scouting apple orchards next to soybeans and other stink bug hosts such as Russian olives and tree-of-heaven is recommended.

Summary of Berrien County apple maturity samples taken Sept. 23, 2013.

Date sampled

Firmness lb pressure (range)

Starch conversion (range)

Brix (range)

Golden Delicious

Sept. 23

16.4 (15.5 - 17.4)

3.3 (1.8 - 6.4)

13.8 (12.7 - 14.6)

Red Delicious

Sept. 23

17.8 (16.9 - 18.8)

2.4 (1.8 - 3.0)

10.9 (9.7 - 11.6)

Fuji

Sept. 23

19.4 (18.9 - 20.5)

3.5 (2.0 - 4.6)

12.5 (11.9 - 13.0)

Idared

Sept. 23

17.9 (16.3 - 17.5)

1.7 (1.4 - 2.0)

11.7 (11.4 - 12.1)

Golden Delicious (seven sites sampled Sept. 23)
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 16.4 (15.5 - 17.4) compared to last week’s 17.4 lb, starch conversion 3.3 (range 1.8 – 6.4) compared to last week’s 1.7, and brix of 13.8 with last week value of 13.5. For this variety the target fruit conditions for long term CA storage is 17 lb firmness or greater and minimum of 3.0 on the starch conversion scale. Predicted harvest date for central Berrien County is Sept. 25, 2013. Four of seven blocks tested had the more advanced fruit at sufficient starch conversion test maturity for long term CA.

Red Delicious (six sites sampled Sept. 23)
This week’s tests show firmness of 17.8 (range 16.9 – 18.8) about the same as last week, starch conversion 2.4 (range 1.8 – 3.0) compared to last week’s 2.0, and brix 10.9, last week 10.6. Predicted harvest date for central Berrien County is Oct. 3, 2013. For this variety, the target the fruit conditions for long term CA is fruit firmness of 18 lb or greater and minimum of 2.5 for the starch conversion index. Two of six sites tested had the more advanced fruit in the orchards testing starch conversion in the mature category.

Fuji (five sites sampled Sept. 23)
This week’s tests show firmness of 19.4 (18.9 - 20.5), starch conversion 3.5 (2.0 - 4.6), and brix 12.5 (11.9 - 13.0). For this variety the target the fruit conditions for long term CA is fruit firmness of 17 or greater and minimum of 3.0 for the starch conversion index. Predicted harvest date for central Berrien County is Oct. 20, 2013. The samples indicate that some of the Fuji blocks tested have the more advanced fruit in the mature range for starch conversion, although background color is generally green and sweetness is still relatively low. Fruit that are clustered or in shaded areas of the tree are considerably less mature. Generally excellent firmness will allow delay of harvest until skin color, size and brix improves.

Idared (two sites sampled Sept. 23) This week’s tests show firmness of 17.4 lb (range 16.3 – 17.5), starch conversion 1.7 (range 1.4 - 2.0) and brix 11.7 (range 11.4 - 12.1). Predicted harvest date for central Berrien County is Oct. 5, 2013. For this variety the target the fruit conditions for long term CA is fruit firmness of 15 lb or greater and minimum of 3.5 for the starch conversion index.

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

Idared

14

15

16

3.5

6

*CA = controlled atmosphere storage

The SW Michigan Apple Maturity Report is produced by: Bill Shane, Michigan State University District Extension Educator for Fruit and Marketing, Benton Harbor, 269-944-1477 (ext 205), fax 269-944-3106, Diane Brown-Rytlewski, Berrien County Extension Educator, Benton Harbor, 269-944- 4126 and Mark Longstroth, District Extension Educator for Fruit and Marketing, Paw Paw, Mich.

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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