MSU Extension Apples

Apple maturity testing will occur weekly for northwest Michigan beginning now through the end of harvest. Reports will be sent out every week following the Michigan State University Extension fruit team apple maturity calls on Wednesday mornings.

In the northwest region, growers are harvesting Premier Honeycrisp and Minneiska. Apple size is variable across orchards, but size does seem to be improving since last week, at least from the seat of the truck perspective.

Rain is forecast for today, Sept. 9. The next rain is predicted for next Monday and Tuesday, Sept. 14 and 15. Temperatures are predicted to cool by the weekend. We have noticed substantial bird damage across all blocks of apples this season.

Weather

The weather over the Labor Day weekend was beautiful—sunny and warm in the day and cool at night. This weather is perfect for coloring up apples. Friday, Sept. 4, was hotter and humid—it seemed much warmer than the thermometer read, but the humidity made it feel hot (RH = 87.2%). Over the weekend, the humidity dropped a bit, and it was sunny and drier.

Overnight temperatures have started to cool, and we have been in the 50s and low 60s over the weekend. By September 11, overnight temperatures are predicted to be in the low 50s. Daytime temperatures are also predicted to cool, and we will be seeing daytime highs in the 60s and low 70s rather than the occasional 80 degrees Fahrenheit.

We received 0.21 inches of rain on September 3 and are predicted to receive more on September 9 (75% chance). Conditions are still fairly dry across the region.

How to read maturity tables

Each week, an apple maturity report will be provided and will include average values for several apple samples for varieties nearing maturity. Maximum and minimum values are included in tables below for the highest and lowest individual fruits evaluated for each, to give a full spectrum of maturity. Samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted. Samples were collected from 8+ locations in Leelanau County. We also test some apples from Old Mission Peninsula.

For more information about apple maturity testing, review these resources compiled by the MSU Extension tree fruit team.

• Predicted apple harvest dates for 2026 from MSU.
• More information on harvest management tools and timings can be found in this article.
• Guidelines from MSU to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety.
• New starch charts for evaluating apple maturity in Michigan from Michigan State University
• Predicting apple maturity and starch chart from Cornell University.
• Starch chart for Honeycrisp Apples developed by Washington State University.

Maturity information for the Northwest Region

Apple maturity is occurring earlier than normal this season in most other growing regions in the state. In northwest Michigan, our predicted harvest dates line up with normal harvest dates, but we are seeing variability between orchard blocks and sites. Apples seem to be maturing on the faster side this week compared to last week. Apples are less firm and showing an increase in starch readings. Color has also improved. Be sure to test maturity block by block.

Premier Honeycrisp

Fruit were sampled from one location on September 8 in Leelanau County. Individual samples represent fruit closest to maturity or first pick fruit in each block. The red color was low in this block (57%), but other Premier blocks have excellent color. Starch rating is 6.4. Pressure is 15.3 lbs, and Brix are at 11.2. These apples are mature and ready to be picked, despite the lack of color. Growers will need to weigh color and maturity for Premier harvest.

Bitter pit may develop on fruit in some locations. As a reminder, fruit that are high risk or are more susceptible to bitter pit development may be in blocks with younger trees, high-risk rootstocks, high-vigor trees, or low crop loads. Large fruit are also more susceptible to bitter pit development than small fruit. High bitter pit-risk fruit should be cooled quickly to the recommended 38 F storage temperature, as conditioning will exacerbate bitter pit. High risk fruit should be marketed as soon as possible. Fruit intended for longer storage should be pre-conditioned, with recommended conditions of 50 F (room temperature) for 5-7 days.

Minneiska

Minneiska fruit were not sampled this week as most growers with this variety are in harvest. This variety has colored nicely, and they are eating better this week than last. Overall, growers have been pleased with this variety this year. This variety can be plagued with issues, but growers have been optimistic about the quality of Minneiska this year.

Gala

Gala fruit were sampled from five locations on September 8. Red color is at 73%, which is up from the 67.2% last week. Fruit firmness is similar to last week at an average of 22.6 lbs of pressure. Starch is an average of 1.3, which is numerically lower than last week—all said, the apples are still immature. Sugars are an average of 10.2 Brix, and these numbers are higher than the 9.8 Brix from last week. Gala size looked better this week than last week, so the bits of rain we received are helping. We also noted growers pruning for color in Gala blocks this week.

Honeycrisp

Fruit were sampled from seven locations on September 8. Fruit are immature, but the maturity has advanced since last week. Average pressure has dropped to an average of 18.3 lbs compared to 20.8 lbs last week, and starch rating was 2.4, which is up from last week’s 1.4 start removal average. Sugars are at 11.1 Brix this week, and this was the exact number from last week.

Honeycrisp on other parts of the state have moved quickly in maturity—watch the variety closely so the fruit do not go from under- to overmature in a short amount of time. We did test some outlier fruit that had starch removal of 8, which indicates over maturity; however, these fruit were few but concerning.

McIntosh

We have few blocks of McIntosh to sample, but we tested one orchard in Leelanau County on September 8. This is an older strain of Mac, and there was little color on the apples so far. These trees are also big, so color will be slow to develop, but color has improved compared to last week. This variety is immature. Brix also seems slow to increase in this variety; there was no increase in brix readings from last week until this week.

Apple maturity sampling parameters

• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested. Indicates surface area covered in red and intensity of red color.
• Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
• Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
• Starch For Honeycrisp: will typically be rated using the standard Michigan State University starch scale (1-8). However, a separate starch chart for Honeycrisp Apples developed by Washington State University (scale 1-6) also exists.
• Brix = % sugar measured with Atago PAL-1 Pocket Refractometer

Looking for more? View Michigan State University Extension’s Apple page for regional reports throughout the state and additional resources.