Grand Rapids area apple maturity report – October 22, 2014

The end of the 2014 apple harvest is in sight.

General comments

Jonagold harvest is nearly complete on the Ridge, and only fruit with harvest management materials are left waiting for some color. Growers are waiting for a bit more color on Fuji and other late varieties like Cameo. Some growers with no late varieties are reporting they just finished with their harvest while others are saying they need another week or so to get to Fuji, etc. The very cold, frosty nights in the last week will likely loosen fruit a bit. The bright, clear, sunny and warmer weather forecasted for later this week will certainly be good for color development. Keep a close eye on remaining blocks in case fruit drop related to the weather becomes an issue.

This will be the final written apple maturity report for the Grand Rapids, Michigan area and west Michigan.

For the Hart/Shelby, Michigan area, growers can expect harvest dates 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 apple maturity samples measured Oct. 21, 2014


Avg. ethylene (ppm)

% Fruits with ethylene over 0.2 ppm

Color % (range)

Firmness lbs. pressure (range)

Starch (range)

Brix (range)




96 (80-100)

14.4 (11.5-18.2)

6 (4-7)

12.9 (11.8-14.7)




71 (90-100)

16.2 (14.8-17.8)

7.2 (7-8)

12.3 (12-12.8)




94 (40-95)

16.1 (14.8-17.8)

7.2 (7-8)

12.3 (12-12.8)

Granny Smith



27 (10-40)

19.7 (16.4-24)

4.1 (3-5)

13.2 (13-14)


Empire are mostly harvested. Samples this week show a giant leap forward in internal ethylene production with 75 percent of fruits over 0.2 ppm; the remaining 25 percent of fruits are just under the 0.2 ppm mark. Color, pressure and brix continue to be excellent on Empire. Starch clearing is at 6 this week compared to 4.9 last week. Empire are in a short-term controlled atmosphere (CA) storage window now for fruits not treated with harvest management tools.


There are a few Jonagold still hanging, mostly for a second picking. Our samples this week show a jump in internal ethylene in Jonagold with 100 percent of fruits tested well over 0.2 ppm (the average ethylene was 3.2). Color is down slightly as it’s the second pick we are sampling from. Firmness is still very good at 16.2, Starch clearing is up to 7.2 from 7.1 last week, with all fruits in the 7 to 8 range. Brix continue to be good at 12.3. Any Jonagold still hanging for color are still in the long-term CA window, but that will quickly change in the next day or two to a mid-term CA storage window. Bitter pit is beginning to show up on Jonagold.

Ida Red

Ida Red came off trees quickly in the last week. Our sample block has been harvested. Any left hanging are most likely still in the long-term CA storage window, but will quickly move to the mid-term CA storage range by the end of this week.


Our Rome block was harvested similar to all other Rome blocks. Color bleeding has been an issue in Romes left to hang this long.

Fuji (Aztec)

Our Fuji block has been harvested, but there are many blocks still out there waiting for some color. The predicted Fuji harvest date for the Grand Rapids area is Oct. 28, so they can hang a bit longer if needed. Keep an eye on them for loosening fruit due to the frosts of late.


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, but they hang and stay hard for a long time so you can get to them when time permits. Our third week of Cameo samples indicate there has been a marked movement forward in maturity. Internal ethylene moved the most with 90 percent of fruits this week over 0.2 ppm ethylene. Color has improved greatly with 95 percent red color compared to 64 percent last week. Firmness is still excellent at 16.1 pounds, similar to last week’s 15.9 pounds. Brix levels are at 12.3 which is similar to last week’s 12.4. Cameo could be harvested now or they could be left to hang a bit longer if color needs improving.

Granny Smith

This late-season variety was sampled for the second week. All maturity indices indicate that Granny Smith is immature, but nearly there for any long-term CA storage. For retail market sales, they need a little more time to develop better flavor. Internal ethylene measurements show 40 percent of fruits over 0.2 ppm. Fruit firmness is very high at 19.7 pounds pressure on average compared to 19.2 last week. Starch clearing ratings have moved from all 2’s and 3’s last week to an average of 4.1 this week with levels ranging from 3 to 5. Brix have improved from 12 last week to 13.2 this week.

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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