Michigan apple maturity reports – October 13, 2011

Each week, MSU Extension educators test apples for maturity in their region and report the status.

This week’s regional reports:

Grand Rapids Area
Grand Rapids Area

Grand Rapids Area – Phil Schwallier, Amy Irish-Brown and Denise Ruwersma , Michigan State University Extension

General comments

Clear, sunny days have been excellent for apple harvest. There has been some drop reported, but nothing extreme. It is interesting to note that trees seem to be shutting down on the early side this year. This could be due to several reasons: a stressful, hot summer; the rather dry beginning to harvest season; a heavy crop load; and the cold snap a few weeks ago caused leaves to senesce. It is most likely a combination of these factors. If you look at other large landscape trees, the same can be noticed.

Summary of Grand Rapids apple maturity samples tested October 11, 2011

Variety Predicted Harvest Date Avg. Ethylene (ppm) % Fruits with Ethylene over 0.2 ppm % Red Color (range) Firmness lbs pressure (range) Starch (range) Brix (range)
Red Delicious 6-Oct 3.58 80% 96%(95-100) 17.5 (16-19) 6 11.2 (10.9-12)
Cameo 8-Oct? 1.52 90% 96% (90-100) 18.3 (15.6-20.6) 5.9 (3-7) 13.1 (13-13.5)
Idared 12-Oct 1.84 100% 84.5 (60-100) 19.9 (13.8-18.8) 4 12.2 (11.4-13)
Rome 17-Oct 0.191 10% 97% (90100) 21.1 (20.5-22) 6.9 (6-8) 11.3 (10.9-12)
Fuji 27-Oct 0.312 50% 41% (15-70) 18.9 (16-21.5) 6.5 (6-7) 12.4 (11-13)
Granny Smith 1-Nov 0.023 0% 15.5% (5-50) 20.3 (18.5-21.5) 6 11.5 (11-12)

Red Delicious

Many Reds have been or will be picked in this week. They are ready for long-term CA storage. There was a marked jump in internal ethylene this week compared to last. A little water core is also being reported. It would be best to get Red Delicious in bins and in storage soon.


Samples from this week show much improvement in maturity compared to last week and they are ready for harvest. Cameo is now in the mature window and it does appear (from this year’s data) that Cameo maturity will fall into the range of Red Delicious or just behind it.

Ida Red

Ida Red has had much improvement in maturity from last week. Internal ethylene has moved to an over mature level with fairly high readings and all fruits well over 0.2 ppm. Starch clearing is a solid 4 which indicates they are right there for long-term CA storage. This is a good time to get Ida Red harvested if you haven’t already. The predicted harvest date was October 12, so they are right there this year. Finish up Red Delicious first and then move to Ida’s.


Fruit are still immature for the most part, but readings are ahead of what is expected. The predicted harvest date for Rome in general is October 17 and that date is appearing to be a good target for 2011. Internal ethylene is still quite low with only 10 percent of fruits over 0.2 ppm. Color and firmness are excellent, as usual. Starch conversion is higher than normal at 6.9 on average, which indicates mature fruits. Brix isn’t too bad at 11.3. As growers finish up Red Delicious and Ida Reds, they will move right into Romes.

Fuji (late season)

This is the third week of sampling for late season Fuji. They were making advancement in maturity faster than expected, but it seems to have slowed the pace from last week a little. Overall, they are still immature, but the numbers indicate they will most likely be ready for long-term CA well ahead of the October 27 predicted harvest date. There are many different cultivars of Fuji now, so the predicted harvest date might not coincide well with all of them.

Granny Smith

Granny Smith were sampled for the second week in a row and are still immature. There is almost no internal ethylene being produced and firmness is very hard. The starch clearing was a bit surprising at 5 last week and is 6 this week. Brix readings are about the same at 11.5 this week compared to 11.6 last week. The normal harvest date for Granny Smith in the Grand Rapids area is around November 10. We continue to predict they will be earlier this year – perhaps around November 1.

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