Grand Rapids area apple maturity report – October 2, 2013

Apple harvest is at a peak, but labor is not.

General comments

In the Grand Rapids, Mich., area, harvest is moving slowly with a lack of labor. Ninety percent of Galas have been picked. Honeycrisp are finished for the most part. Growers are trying to get to McIntosh and Empires as time and labor allows. It’s very frustrating for those who lack adequate labor this year to be moving so slowly through harvest. The forecast for five days of rain is not going to help.

Keep in mind that we sample fruit until the window for long-term storage begins and that we only consider fruits that have not been treated with ReTain, NAA or Harvista. If you use these harvest management tools, you need to take that into consideration for your harvest plans.

Summary of Grand Rapids apple maturity samples taken Oct. 2, 2013


Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Color % (range)

Firmness lbs pressure (range)

Starch (range)

Brix (range)




83 (50 - 100)

17 (14.5 - 20.8)

4.9 (2 - 8)

13.2 (11 - 17)




96 (75 -100)

14.8 (11.2 - 17.5)

6.1 (4 -8)

13.1 (11.5 - 14)




44.7 (20 - 85)

13.7 (10.5 - 19.2)

7.4 (3 - 8)

12.3 (10 - 14)

Red Cort



85 (75 - 100)

15.3 (13.3 - 17.3)

2.5 (2 - 4)

12.6 (12 - 13)




32 (10 - 60)

17.7 (15.3- 23.4)

5.9 5 (4 - 8)

12.1 (12 - 13)





13.7 (12 - 16.5)

6.7 (5 - 8)

12.4 (12 - 13)

Red Delicious



98 (90 - 100)

16.6 (15.5 - 18)

1.9 (1 -2 )

11.5 (10 - 13)

Ida Red



69 (10 - 95)

15.8 (11.5 - 18.6)

2.3 (2 - 3)

10.9 (10 - 12)


Gala untreated with harvest management aids are in the short-term CA storage window and should be marketed for fresh retail sales at this time.


Most McIntosh have been harvested on the Ridge, but those still hanging need to be harvested soon. All maturity measurements indicate that McIntosh is in a short-term CA window now. Ethylene has been quite high in McIntosh samples and this will soon start the chain of events that cause fruit to drop. If you have used NAA alone as a stop drop material, remember you need to reapply it again in seven days if you will not be able to get that fruit harvested prior to 10 days after your first application.


Honeycrisp harvest is wrapping up on the Ridge. Maturity indices tell us that they are very ripe if not treated with harvest management aids. They have excellent flavor and crunch still.

Red Cortland

Fruits sampled this week indicate maturity is just peaking and Cortland are still in the long-term CA storage window, but moving quickly to mid-term. Ethylene levels are very high; firmness is still excellent at over 15 pounds; starch ranges from 2 to 4; and brix average 12.6, up slightly from last week.


Empire is moving out of the long-term CA storage window and into the mid-storage range. They should be harvested by the end of the week to get the best storage quality if you have not used harvest management sprays. For fruits treated with ReTain, we see lower ethylene levels.


This should be a big week for Jonagold harvest where fruits are not treated with harvest management materials. I neglected to include written text about Jonagold last week when internal ethylene was starting to increase with 40 percent of fruits over 0.2 ppm. This week’s samples show no fruits over 0.2 ppm which goes along with what we’ve been hearing, that maturity levels are sometimes all over the board this year depending on the block and the strain. Overall, Jonagold hasn’t moved much in maturity from last week to this week with firmness still excellent at nearly 18 pounds; starch from 4 to 8 with an average of 5.9 (up slightly from 5.6 last week); brix levels are about the same at 12.1 this week whereas it was 12.6 last week.


Sampling this week was again from Ruby Jons, so color is excellent. All fruits registered internal ethylene over the 0.2 ppm indicator compared to 40 percent last week. Fruit firmness averages 13.7 pounds this week compared to 15.4 pounds last week. Starch clearing is higher at 6.7 this week (3.9 last week). Brix levels are only slightly improved at 12.4 this week compared to 12.3 last week. The predicted harvest date of Sept. 29 was a good date early harvest of Jonathan for long-term CA storage – this is in fruits with no harvest management materials applied. By next week, Jonathans will move into a mid-term CA storage window for untreated fruit.

Golden Delicious

The predicted harvest date is today, Oct. 2, and this is a good target for the majority of Golden Delicious harvest. Growers will need to get to Goldens as time allows, but they are now just entering the long-term CA storage window. We do not have samples from this week to report data.

Red Delicious

This was the second week of testing for Red Delicious and they have moved forward in maturity very little. Internal ethylene shows very few fruits over 0.2 ppm. Firmness is still very good at 16.6 pounds compared to 16.8 last week; fruit are very starchy at an average of 1.9 (1.1 last week) and brix are very low at 11.5 compared to 11.2 last week. The predicted harvest date for Red Delicious is Oct. 5 and from the data this week, that date will be about right or perhaps a bit early for long-term CA storage.

Ida Red

The predicted harvest for Ida Red was estimated for Oct. 10. Fruit sampled this week is showing movement towards maturity, but overall Ida Red is still immature and at least seven to 10 days from the long-term CA storage window. Internal ethylene is up a bit this week with 40 percent of fruits over 0.2 ppm compared to 20 percent last week. Fruit firmness is down from 17.7 pounds last week to 15.8 this week. Starch clearing averages 2.3 compared to 1 last week. Brix levels have decreased a bit from 11.7 last week to 10.9 this week, but are expected to improve greatly in the next seven days.

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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