Southeast Michigan apple maturity report – October 22, 2014

With a good weather forecast for the next week, apple growers are seeing that the harvest finish line is near.

General apple harvest comments

Apple harvest is quickly winding down across the region. Most apple growers report they will finish apple harvest in seven to 10 days if the weather predictions hold true. Growers are picking a wide number of varieties this week, finishing up on later maturing strains for some varieties that were mostly mature last week, and going back to finish harvest of Retain-treated blocks.

Varieties ready for harvest this week include Red Delicious (finally), finishing later maturing Northern Spy blocks, a few early maturing Ida Red blocks and new to the list this week is Cameo. Ida Red has been very slow to mature this season, as was Red Delicious. Varieties needing more time to mature include Winesap, Braeburn and Goldrush.

Internal ethylene levels are typical for this time of the season and fruit color has continued to improve. Fruit firmness or pressure has remained firm in the past week. The brix or sugar levels have risen sharply in the last week, jumping an average of over 0.75 percent compared to last week. Lastly, many varieties are finally starting to eat well.

This week, I repeated apple maturity testing on six varieties tested last week and added a new variety, Goldrush. As with most every season, the apple maturity data this late in the season may be skewed a bit as many varieties are harder to find (so my sample size declines) and blocks have been spot-picked once, so the remaining fruit is less mature. This will be the last apple harvest report for the season.    

Apple maturity in southeast Michigan for apples harvested Oct. 20, 2014


% Fruits with ethylene over 0.2 ppm (range)

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %

Red Delicious

 60 (40-100)

92 (91-93)

15.6 (14.8-16.3)

4.9 (4.6-5.4)


Ida Red

100 (100-100)

71 (55-90)

15.8 (14.5-17.0)

2.2 (1.0-3.0)


Northern Spy

 40 (40-40)

64 (40-80)

18.4 (15.4-21.0)

5.3 (4.0-6.0)



 0 (0-0)

78 (65-99)

20.2 (17.0-22.2)

3.8 (2.0-7.0)



 30 (0-60)

76 (72-80)

22.2 (22.0-22.4)

1.9 (1.1-2.6)



 0 (0-0)

20 (10-40)

23.5 (20.2-26.2)

1.0 (1.0-1.0)


Individual variety results

Red Delicious (Redchief strain) was sampled for the fifth week of the season and was very slow to mature this season. Starch index rose a point where they are ready to harvest. This week, 60 percent of fruit tested produced internal ethylene levels greater than 0.2 parts per million (ppm). Fruit color remains excellent at 92 percent and pressure averaged close to the same as last week at15.6 pounds. The background color has changed in the last week to yellow. The starch removal averaged 4.9 this week, up from 3.4 last week. The brix jumped from 12.5 percent last week to 13.7 percent this week. Water core and moldy core are being found in about 30 percent of the fruit. Lastly, Red Delicious are finally eating better in the last week.

Ida Red was sampled for the fifth week of the season and is still not mature at many farms. Why this variety and Red Delicious were so late to mature this season is still unclear. I believe that Ida Red still needs another week to mature. This week, 100 percent of fruit tested produced internal ethylene levels greater than 0.2 ppm. Fruit color improved to 72 percent and pressure was unchanged at 15.8 pounds. The starch removal averaged 2.2 and the brix was at 12.7 percent.

Northern Spy was sampled for the sixth week of the season. I was only able to find one block of Northern Spy to sample this week as most were harvested last week. This week, Northern Spy’s are over-mature. Internal ethylene levels in fruit greater than 0.2 ppm are at 40 percent. Fruit color remained steady in the last week at 64 percent, pressure averaged 18.4 pounds, and starch removal averaged 5.3, up from 4.4 last week. The brix was at 12.8 percent this week.

Cameo was sampled for the fourth week of the season and is now ready for harvest. Fruit color improved to 78 percent, up from 51 percent last week, and pressure averaged 20.2 pounds. The starch removal averaged 3.8, up from 2.4 last week, with a brix still the best of any variety tested at 16.3 percent.

Winesap was not tested this week. I could not find enough of a sample in any block as they were all harvested. I did find a few apples that were missed and based a taste test. This variety is still not ready to harvest. I believe that it is still five days away.

Braeburn was sampled for the second week of the season and appears to be at least a week away from being ready on our earliest maturing sites. This week, 30 percent of fruit sampled produced internal ethylene levels greater than 0.2 ppm. Fruit color improved from 69 percent last week to 76 percent this week, and background color dropped from 3.3 last week to 2.5 this week, so they still have a fair amount of green background color. The pressure averaged 22.2 pounds and the starch removal averaged 1.9, up from 1.3 last week. The brix has jumped from 12.4 percent last week to 13.5 percent this week.

Goldrush was sampled for the first week of the season and appears to be a very long way off at this time. None of fruit sampled produced internal ethylene levels greater than 0.2 ppm. Fruit color is 20 percent and pressure averaged 23.5 pounds. The starch removal averaged 1.0 with a brix at 14.1 percent.

Predicted apple harvest dates

Each year we publish a predicted harvest date for three varieties for many locations across the state. This year’s dates can be seen at “Predicted 2014 apple harvest dates,” published July 17. The table below lists the bloom and harvest dates for the Michigan cities Deerfield and Romeo. You can adjust your predicted harvest dates based on your bloom dates. The harvest dates are based on a long established formula using the bloom date and temperatures for 30 days post-bloom. These dates are an estimate, and from the data I generated from this week’s samples, I believe that these harvest days are going to be fairly close to the actual dates for a variety nearing maturity.

Predicted harvest dates for southeast Michigan

Full bloom date

 Predicted harvest dates






















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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