Grand Rapids are apple maturity report – October 15, 2014

Heavy rains have slowed harvest only slightly.

General comments

On the Ridge, Jonagold harvest is the major variety being worked on this week, with Red Delicious being worked on where color is best. We have noticed a general trend in slight increases in fruit firmness. This could be due to the rainfall over the last two weeks and raises concerns for longevity of fruits for long-term controlled atmosphere (CA) storage. Where color and size are adequate, Jonagold, Red Delicious and even Ida Red need to be harvested soon.

There seems to be a great deal of variability this year in the apple harvest timeline, and it’s causing some frustration in trying to plan. We are getting to the stage where all apples left, save those very late varieties like Braeburn and Granny Smith, are ready for their final harvest in the next two weeks.

Below is the table of Grand Rapids, Michigan area predicted harvest dates for remaining apple varieties. We are surprised by how late the maturity is compared to these dates for 2014.

Predicted apple harvest dates for Grand Rapids, Michigan


Normal date

2014 predicted date




Golden Delicious



Red Delicious



Ida Red















For the Hart/Shelby, Michigan area, growers can expect harvest dates for that area to be behind the Grand Rapids, Michigan area using this guide: along the lakeshore approximately six days behind Grand Rapids, Michigan; areas inland about four days behind.

All the samples we take for these maturity readings are untreated with any harvest management materials (ReTain, Harvista, Ethryl, etc.) unless it is noted with the variety.

Summary of Grand Rapids, Michigan apple maturity samples measured Oct. 14, 2014


Avg. ethylene (ppm)

% Fruits with ethylene over 0.2 ppm

Color % (range)

Firmness lbs. pressure (range)

Starch (range)

Brix (range)




94 (80-100)

14.1 (11.7-17.4)

4.9 (3-7)

12.2 (11.4-13)




80 (25-100)

15.2 (13-20)

7.1 (6-8)

12.7 (11-14)

Red Delicious



98 (90-100)

14.7 (12.2-16.5)

3 (2-5)

10.8 (10-12)

Reds + ReTain



90 (50-100)

14.8 (12-17.4)

3.4 (2-7)

10.6 (9.8-11.6)

Ida Red



86 (60-98)

14.5 (13.2-15.2)

3.4 (2-4)

11 (10.4-11.8)

Fuji (Aztec)



97 (90-100)

17.3 (15.5-19)

4 (3-5)

13.6 (13.5-14)




90 (80-98)

19.4 (17.2-21.5)

4.1 (3-8)

12.8 (12-13)




64 (40-95)

15.9 (13.4-18.2)

7.2 (4-8)

12.4 (11.6-13)

Granny Smith



9.2 (2-15)

19.2 (16.2-23)

2.8 (2-3)

12 (11.4-12.8)


There are not many Empire left on trees and this year’s crop on the Ridge resulted in very beautiful fruit. Samples this week show a slight increase in internal ethylene at 42 percent of fruits over 0.2 ppm. Color is excellent on Empire at 94 percent on average. There is a bit of bleeding of red color into the skin just at the surface of about 10 percent of Empire fruits. Firmness is still very good at 14 pounds pressure. Starch readings averaged 4.9 with individual fruits measuring in the range of 3 to 7. Brix is good at 12.1. Empire are in a mid-term CA storage window now and will quickly move to a short-term window by the end of the week.


Our Cortland block has been harvested. Any left hanging are most likely in the short-term CA window.


Jonagold continue to be harvested at a slow and steady pace. Samples this week have made a definite forward movement in maturity and are in the window for long-term CA storage. They will move quickly out of best condition for CA storage in the next seven days. Our samples this week show 58 percent of fruits sampled showing ethylene over the 0.2 ppm climacteric. Firmness is still similar to the last two weeks at 15.2 pounds. Starch clearing is up to 7.1 from 6.1 last week. Brix improved from 11.6 to 12.7 this week. With all the rain lately, it would be wise to not wait too long to get Jonagold off, especially those blocks with really large fruit already. The risk for bitter pit could increase the longer they hang.

Golden Delicious

Our Golden Delicious block has been harvested. It is estimated that Goldens are now in a mid- to short-term CA storage window.

Red Delicious

This is our third week of sampling Red Delicious. Ethylene production has increased with 60 percent fruits sampled with ethylene over 0.2 ppm. Color is excellent on Reds this fall. Fruit firmness had decreased from 16 to 14.7 pounds pressure. Starch clearing is improved a little at 3 this week compared to 2.4 last week. Brix continue to be on the low side at 10.8 which is only slightly up from last week’s 10.3. Our predicted harvest date for Red Delicious was Oct. 10 and this seems to be a good target for long-term CA storage for your blocks with adequate red color.

In the chart above, numbers from Red Delicious treated with ReTain are included as many growers have been asking about it. The ReTain-treated Red Delicious have slightly less ethylene production with only 30 percent fruits over 0.2 ppm; red color is slightly less at 90 percent compared to 98 percent in untreated. Fruit firmness, starch clearing and brix are nearly the same for treated and untreated.

Ida Red

The third week of Ida Red samples show a slight improvement in maturity, but a bit less than expected with a predicted harvest date of Oct. 14. Ethylene production is similar to last week with 50 percent of fruits sampled over the 0.2 ppm climacteric. Color is improved at 97 percent red color compared to 67 percent last week. Firmness continues to be lower than expected for this time of year, but is actually increased slightly from the previous week at 14.5 pounds this week compared to 13.9 pounds last week. We are seeing slight increases in pressure levels in several varieties, perhaps due to the recent rainfall.

Starch readings in Ida Red have increased from 1.8 last week to 3.4 this week. Brix levels are still quite low and have not changed much at 11 this week compared to 11.1 last week and 10.7 two weeks ago. Ida Red is now in the long-term CA storage window and growers should start harvesting when time allows for the best CA quality fruit you plan to pull out of storage after March or April next year.


Ethylene is very low with no fruits over 0.2 ppm. Color is very good at 90 percent red color. Fruit is very hard at 19.4 pounds pressure. Starch clearing is really perfect for long-term CA storage at 4.1. Brix are good at 12.8. There is bleeding of red color being reported in some Rome blocks. Harvest Romes as time allows – many have already been harvested and put away.

Fuji (Aztec)

Our regular (late) Fuji this year is the Aztec strain. Ethylene levels have improved compared to last week with 83 percent of fruits over 0.2 ppm ethylene compared to 40 percent last week. Color has improved greatly at 97 percent red color compared to 73 percent from the last two weeks. Fruit are still very hard at 17.3 pounds pressure, which is up slightly from last week’s 16.9 pounds. Starch clearing is up slightly at an average of 4 this week compared to 2.8 last week. Brix continue to be very good at 13.6, up from 12.9 last week.

The predicted Fuji harvest date for the Grand Rapids, Michigan area is Oct. 28, so we are likely to see a great improvement in Fuji maturity indices over the next 10 days. They are not quite there yet for long-term CA storage, but close. Size is very nice on Fuji this year.


There are not many Cameo planted in Michigan and growers tell me they target harvest for about a week after Rome or maybe in the Fuji window or a little later. They hang and stay hard for a long time so you can get to them when time permits. Our second week of Cameo samples indicate that there is a slight forward movement in maturity, but they are only slowly changing at this time. Only 10 percent of fruits this week were over 0.2 ppm ethylene compared to 30 percent last week. Color improved only slightly from 57 percent red color last week to 64 percent this week. Firmness is still excellent at 15.9 pounds, but did decrease from last week’s 17.6 pounds. Brix levels are improving at 12.4 this week compared to 11.9 last week.

Granny Smith

This late-season variety was sampled for the first time this week. All maturity indices indicate that Granny Smith is very immature. No fruits are over 0.2 ppm. Fruit firmness is very high at 19.2 pounds pressure. Starch clearing ratings are all 2’s and 3’s. Brix are very good at an average of 12 so far.

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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