Northwest Michigan apple maturity report – September 24, 2014

Apples are maturing slowly, but warm and sunny weather should move fruit along this week. We expect apples to be ready for harvest close to the predicted harvest dates for northwest Michigan.

After a rainy weekend, the clouds have cleared and warm and sunny conditions are predicted for the entire week and into the weekend. This weather is perfect for picking apples, but many blocks are still not quite mature, even for long-term storage. Quality continues to look good across all apple blocks, and with the cool night temperatures, color continues to improve. The predicted sunny days and cool nights will continue to improve color.

Overall brix levels have moved very little from last week, and the starch index readings from the varieties we collected this week are similar to our numbers from last week. This weekly information reminds us that in this cool year, apples mature much more slowly than in warm seasons. Our McIntosh predicted harvest date for northwest Michigan is Sept. 26, and with the warm temperatures predicted, many McIntosh orchards in the southern end of our growing region will be close to harvest around that target date.

Summary of northwest Michigan apple maturity samples taken on Sept. 24, 2014


Color % (range)

Firmness lbs. pressure (range)

Starch (range)

Brix (range)


78.8 (70-93)

19.4 (18.0- 21.1)

1.1 (1-2)

10.7 (10.6-10.7)


87.0 (82-90)

16.2 (14.3-17.9)

2.9 (1.5-4.1)

12.6 (11.5-13.3)


79 (63.5-91)

16.5 (15.1-17.1)

2.3 (1.9-2.5)

12.4 (11.4-13.4)


70 (68-72)

17 (16.8-17.2)

2.15 (1.7-2.6)

13.3 (13.1-13.5)

Golden Supreme





Golden Delicious





Gala. Immature (three samples). Galas are coloring up and holding firmness. Starch levels and low brix indicate that Galas are not yet mature. Galas have moved very little from last week.

McIntosh. Closer to mature (three samples). Some orchards are mature for long-term storage. There is still variability in maturity between orchards. Color is improving and sugars are increasing slowly. We have had few reports of McIntosh pushing off.

Honeycrisp. Immature (four samples). Color is much improved this week. Firmness is down slightly compared with last week and starch indexes indicate that these apples are starting to ripen. Brix levels are comparable with last week’s measurements.

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.

Dr. Rothwell’s work is funded in part by MSU’s AgBioResearch.

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