Grand Rapids area apple maturity report – October 16, 2013

Favorable fall weather has led to fantastic apple quality.

General comments

If there is a sweet spot to the apple harvest on the Ridge, it occurred in the last week or so. The favorable weather over the past 10 days has helped with getting a lot of fruit off trees and workers, many of whom have never picked apples before, seem to now be in the groove for harvest. It does look like the warmer than normal weather is going to come to an end later this week as a major shift in the jet stream takes place, bringing cooler weather to the Great Lakes. It appears that this cooler than normal weather pattern will stick with us for at least a couple of weeks with rain chances off and on for the next week.

In general, apple quality has been excellent with great fruit finish and little insect damage such as late season codling moth. There is some apple scab on fruit and growers should take note of those blocks for their potential to have higher scab inoculum for the spring of 2014. We are noticing that the predicted harvest dates for later season varieties seem to be later than what is actually happening. Perhaps this is due to all the warmer than normal temperatures we’ve had this fall.

This will be the last formal apple maturity report for the season. We always welcome your input on how to make these reports better and will follow up after harvest with a survey. In the meantime, always feel free to contact either Phil Schwallier at or Amy-Irish Brown at

Summary of Grand Rapids, Mich., apple maturity samples taken Oct. 15, 2013


Avg. Ethylene (ppm)

% Fruits with Ethylene over 0.2 ppm

Color % (range)

Firmness lbs pressure (range)

Starch (range)

Brix (range)




64 (35-85)

20.9 (18.8-23.3)

4.2 (3-6)

12.4 (12-13)




18 (5- 40)

20.9 (17.8-23.8)

3.8 (2-6)

10.7 (9.8-12)

Granny Smith



5.3 (2-10)

18.3 (16.2-22.6)

3 (2-4)

12 (11-13)




2.1 (2-3)

15.1 (13.8-17)

6.1 (5-7)

12.4 (12-12.5)


No samples were taken as all untreated fruit have been harvested. Most Jonagold are now harvested on the Ridge. Only those treated with harvest management products remain. Untreated Jonagold would now be in a short-term CA window or be suitable for fresh fall sale.


The Jonathan situation is similar to Jonagold with any untreated fruit being in a short-term CA stage now. Growers are harvesting Jonathan as processing markets and labor allow.

Golden Delicious

There were no Golden Delicious left where we were sampling. It is estimated that Goldens are in a short-term CA window at this time even if treated with harvest management materials. The ideal harvest date for long-term CA storage was Oct. 2, so they are moving out of condition quickly and should be considered for fresh retail sales only at this time.

Red Delicious

The last week was a major harvest window for Red Delicious on the Ridge. Most have been picked as of this writing, Oct. 16. Fruit in our sampling area were harvested, so no data this week.

Ida Red

The predicted harvest for Ida Red was estimated for Oct. 10 and fruit samples last week indicated that Ida Reds were ready for long-term CA storage at that time. As time and labor allows, growers have been trying to get them in bins. It is expected that Ida Reds will move quickly out of optimal CA storage over the next week if not treated with harvest management materials.


We sampled Cameo for the first time this week. This variety typically reaches maturity shortly after Red Delicious and the maturity numbers indicate that to be true. Internal ethylene is over 0.2 ppm in 40 percent of fruits sampled. Fruit firmness is 15.1 pounds; starch clearing averages 6.1; and brix are excellent at 12.4. Cameo is not a major variety, but it you are new to it, please note that it should be harvested soon for best qualities for long-term storage. It could hang a bit longer for fresh market sales.


Rome was sampled for the second time this week and all levels indicate fruits have entered the window for long-term CA storage. The predicted harvest date for long-term CA storage is Oct. 15. Some Rome harvest has already been done in blocks where bleeding is an issue. Our samples this week were of common Rome, so color readings are lower than with Law Rome or improved Rome cultivars. Fruit firmness is still very good at 20.9 pounds; starch clearing is improved from 3 last week to 4.2 this week; brix readings are similar to last week at 12.4 now. Rome should be harvested as soon as you can get to them.


Predicted harvest date is Oct. 25 and that might be a bit on the late side after the warmer than normal fall weather as some areas are showing maturity of Fuji to be a little earlier than expected. It is expected that the long-term CA window for Fuji will open by the middle of next week. The cooler weather could slow development a bit and make Oct. 25 a good target date for long-term CA storage for Fuji. You will have to closely watch your blocks.


Braeburn was sampled for the first time this week. Internal ethylene is over 0.2 ppm in 40 percent of fruits samples; firmness is very high still at 20.9 pounds on average; starch clearing is 3.8 which still indicates immaturity; and brix are very low at only 10.7 which also indicated immaturity. The predicted harvest date is Oct. 25 for Braeburn and that date should be a good target given the first maturity numbers from this week.

Granny Smith

Granny Smith are still immature according to the first sampled fruit this week. Very few fruits (20 percent) have internal ethylene over the 0.2 ppm climacteric. Fruit are very firm, as usual for Granny Smith, at 18.3 pounds on average. Starch averages 3, indicating immature fruits. Brix are very good at 12 for an average. Granny Smith are usually on of the last harvested varieties on the Ridge, or around Oct. 28 or later.

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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