Grand Rapids area apple maturity report – September 11, 2013

Gala harvest is in full swing this week on the Ridge.

General comments

In the Grand Rapids, Mich., area, apple maturity continues to pan out well with our predicted harvest dates, with some variations towards being on the early side of predicted dates. Some much needed rain fell across much of the central Michigan fruit growing regions from the lakeshore to the general Grand Rapids, Mich., areas. This should help tremendously with fruit size in non-irrigated orchards. Growers with irrigation have reported that they have started to discontinue irrigating in many varieties.

Gala harvest started this week and will be in full swing for the next week or so. Honeycrisp are being spot-picked and McIntosh are being harvested in between Galas as growers can get to them. We have noticed that fruits pick very easily from the trees this year, even when they are several weeks from anticipated harvest. This makes us a bit nervous about potential drop if we get any stormy weather with windy conditions. The use of ReTain plus NAA is your best tool for drop prevention.

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

Summary of Grand Rapids, Mich., apple maturity samples taken Sept. 10, 2013.


Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Color % (range)

Firmness lbs pressure (range)

Starch (range)

Brix (range)




91% (80 - 95%)

18.2 (15.8 - 21.5)

6.1 (3 - 8)

13.5 (13 - 14)




78% (45 - 95%)

15.9 (13.3 - 18.6)

2.4 (1 -4)

11.4 (11 - 12)




32% (15 - 40)

14.5 (12.8 - 16.2)

3.4 (1 - 7)

10.7 (10 - 11)




92% (85 - 95)

15.6 (13 - 18)


11.7 (11 - 12.5)




45.5% (15 - 70)

17.7 (16 - 19.8)

2.2 (1 - 3)

10.7 (9.5 - 11)

Early Fuji



45% (30 - 60)

15.2 (13 - 17.8)

3 (1 -3)

11.2 (10 - 13)




96 (90 - 100)

15.8 (13.6 - 19.2)

2.2 (1 - 3)

11.2 (10 - 12)


Size and color are much improved over last week’s samples. Gala are still in a long-term CA storage window, but will move to a mid-term CA window by next week for fruits not treated with harvest management materials. Redder strains are being harvested now with older, less red strains waiting for more color. All maturity sample numbers indicate improvements towards maturity. Our predicted date of Sept. 10 for long-term storage conditions appears to be spot on for Gala this year. This will be a big week for Gala harvest on the Ridge.


There is definite movement towards maturity and some spot-picking can be done in between Gala harvest needs. Ethylene continues to be lower than expected for this time, but is increased compared to last week’s sampling. McIntosh pick quite easily and drop could be a concern with future windy conditions. Pressure readings are very good at 15.9 pounds on average this week compared to 16.9 pounds of pressure last week. Color is excellent and improving every day. Brix level of 11.4 is slightly lower than last week’s 12.4 and is expected to improve in the next week. Harvest for long-term storage of McIntosh can begin at any time color is right. Our predicted harvest date was determined to be Sept. 15 and that appears to be a good estimate for this year.


Some first color picking is underway in central Michigan for Honeycrisp with the major harvest window expected for a week or 10 days from now, exactly as predicted on Sept. 18, which is also the average harvest date from our records. Internal ethylene is still very low for Honeycrisp – they usually exhibit higher ethylene readings than any other varieties and this might be the reason many fruits are still quite immature. Firmness is lower this week at 14.5 pounds compared to 16.7 pounds last week; Brix is improved from 9.7 to 10.7 this week; starch clearing is rated at 3.4 compared to 1.8 last week. All these maturity numbers indicate that, other than that 10 percent of early ripening fruits, Honeycrisp is a week to 10 days away from optimal harvest window for the Grand Rapids, Mich., area.


This is our first week of Cortland sampling and all numbers indicate it is about 10 to 14 days away from the early harvest window for long-term storage. Ethylene is very low with a few fruits being over 0.2 ppm which indicates the beginning of maturity. Color is excellent (Red Cort was our sample) and firmness, starch and brix are all at immature levels this week.


This week’s sampling shows some movement towards early maturity and Empire is at least two weeks away from the window for long-term CA storage. Our predicted harvest date was Sept. 22 and that appears to be a good estimated early harvest date.

Early Fuji strains

There is movement in our readings, but overall early Fuji strains are about two weeks away from the first harvest window. We tested September Wonder and there are some early Fuji strains that are earlier or later than that cultivar.


This was our first sample for Jonathan and they appear to be right on target for our predicted harvest date of Sept. 28 or 29. All fruits are immature at this time.

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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