Southeast Michigan apple maturity report – September 18, 2013

Apple harvest is in full swing in southeast Michigan.

General apple harvest comments

The pace of apple harvest is quickly picking up steam. Growers are waiting for later and older strains of Gala to color and size to finish on this variety. In the meantime, growers have moved on to the second, third or final picking of Honeycrisp and are stripping McIntosh. Early Fuji is now ready for harvest. Empire, Jonathan, Jonagold and Golden Delicious are quickly approaching maturity. I did not sample Gala and McIntosh this week as I felt we were at their peak harvest window in last week’s sampling.

Warm weather of last week slowed color development for many varieties; however, light frosts of Saturday, Sept. 14, and yesterday morning, Sept. 17, have helped to reverse this. Overall, fruit color is a challenge so far this season. In areas where rainfall has been short, fruit size has been a challenge for several varieties, notably Gala, some McIntosh strains and Jonathan.

Apples are picking easy this week, however fruit drop is not a problem. I am concerned about the potential of fruit drop if we have a windstorm. Most fruit that I see on the ground have been pushed off the tree from neighboring fruit or limbs. Bitter pit remains a problem in Honeycrisp. This week some growers are seeing a fair amount of fruit that is rotting on the tree from black rot. Harvest labor is running short for most apple growers now that harvest is in full swing.

Apple maturity in southeast Michigan for apples harvested on Sept. 16, 2013


% Fruits with Ethylene over 0.2 ppm (range)

Color % (range)

Firmness lbs. (range)

Starch (range)

Brix %



77 (59-94)

13.9 (12.8-14.9)

4.5 (2.2-6.3)


Early Fuji


84 (50-93)

16.0 (14.2-19.1)

3.7 (2.0-5.0)



15 (0-30)

69 (62-75)

17.9 (16.4-17.3)

2.3 (2.2-2.3)




81 (70-100)

16.3 (14.2-19.5)

4.2 (3.0-6.0)



15 (10-20)

60 (36-83)

17.6 (17.5-17.7)

2.9 (2.4-3.3)


Golden Delicious


11 (10-11)

18.8 (14.9-15.8)

4.2 (3.0-5.3)


Individual variety results

Honeycrisp were sampled for the third week of the season. Remember that the most mature fruit has already been harvested in the first few pickings, thus the sampled fruit that is left on the tree is fruit that was too green in earlier harvests. As with all samples taken for the apple maturity program, I collect the most mature fruit from the outside of the tree. Honeycrisp is a variety that requires multiple pickings, and this week growers are in their second, third or fourth picking.

Fruit on the inside of the tree are starting to mature. Again this week all the fruit had internal ethylene levels greater than 0.2 parts per million (ppm). The color of fruit sampled from the outside of the tree is about the same as last week at 77 percent. Fruit firmness has dropped over a pound to 13.9 pounds this week. The starch removal index is 4.5 with a brix of 12.4 percent. There is more bitter pit showing up in Honeycrisp than any other variety so far this season.

Early Fuji was sampled for the third week of the season with 50 percent of the fruit showing internal ethylene levels greater than 0.2 ppm. The color has improved from 60 percent last week to 84 percent this week and the fruit are firm at 16.0 pounds. Fruit starch removal index is 3.7, up from 2.4 last week. The brix is 12.6 percent. Early Fuji is ready for harvest at this time.

Empire was sampled for the second week of this season with internal ethylene levels testing at 15 percent above 0.2 ppm. Color has improved to 69 percent and fruit are firm at 17.9 pounds. I was surprised to see the starch move very little at 2.3 and a brix of 10.4 percent. Empire is still eating green and may be ready for harvest next week at this time. Jonathan and Golden Delicious are actually maturing more quickly than Empire or Jonagold, thus the typical order of ripening and therefore harvest may be mixed up this season. Keep an eye on next week’s report for details.

Jonathan was sampled for the first week of the season. There is starting to be some (30 percent) internal ethylene detected. Color is good at 81 percent and fruit firm at 16.3 pounds. I was surprised to see that the starch removal index is at 4.2 already. They are still eating green and are about four to seven days away from being mature.

Jonagold were sampled for the first week of the season. They, too, are starting to test some (15 percent) internal ethylene levels greater than 0.2 ppm. Color is OK at 60 percent, pressure is good at 17.6 pounds and the starch is 2.9. Jonagold are still eating green and need at least a week to mature.

Golden Delicious was sampled for the first week of the season with Smoothee being the strain tested. They have no internal ethylene levels greater than 0.2 ppm. Color or blush is OK at 11 percent, pressure is good at 17.8 pounds, the starch removal index was a surprising 4.2 and the brix 12 percent. They are still eating green and need at least a week to mature. I will be testing this variety again next week for the complete story on its maturity.

Predicted harvest dates for East Michigan

Full bloom date

 Predicted harvest dates






















The Southeast Michigan Apple Harvest Report is produced by Bob Tritten, district fruit educator, Flint, Mich. Email, office phone 810-244-8555, cell 810-516-3800 and fax 810-341-1729.

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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