MSU Extension Apples

Apple maturity testing will occur weekly for the west central Michigan region 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.

Minneiska harvest is wrapping up. Honeycrisp matured more quickly than expected over the past week. While the predicted harvest date for Honeycrisp harvest in Hart, Michigan, is Sept. 20 according to the Michigan State University Enviroweather model, Honeycrisp is ready to harvest this week at some locations. Gala maturity has not changed much since last week. Apple maturity for Gala blocks that were treated with ReTain have not changed notably since last week. McIntosh and Jonagold are still immature on average but may be ready for harvest at some locations for fruit that will be stored in mid- long-term controlled atmosphere (CA). September wonder Fuji is still immature.

Weather over the past week has been cooler with low temperatures dipping down into the upper 30s and low 40s across the region. Daytime temperatures have warmed since the weekend, and the high on September 9 was 70 degrees according to the Hart Enviroweather station. Day and nighttime temperatures will warm up over the next few days and through the weekend with highs in the upper 70s to low 80s. Low temperatures will be in the 50s. Chances of rain are in the forecast for the end of the week.

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. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted. Samples were collected from two to five locations across Oceana County.

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

• Predicted apple harvest dates for 2025 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 west central region

McIntosh

Fruit were harvested from three locations in Oceana County. Samples include standard McIntosh and RubyMac, which is a red coloring strain of McIntosh and is at a similar stage of maturity to standard strains of McIntosh in the area. Fruit are dark red, and red color is covering 94% of the surface. Background color is light green. Average firmness went down from last week and is an average of 14.6 pounds. Recommended pressure for long-term CA is 16 pounds.

Fruit is still immature at a starch rating of 3.3. McIntosh are mature at a starch test of 5. Sugar levels are excellent at this stage with Brix at 13.2. Fruit size improved from last week, and average diameter of sampled fruit is 3 inches.

Gala

Gala fruit were sampled from five locations in Oceana County this week. Samples in the following table are for Brookfield and Pacific Gala strains. Fruit size has improved slightly from last week, and red color improved from last week and is at 84%. Background color is yellow at 2. Fruit firmness is down slightly from last week at 17.9 pounds of pressure. Starch is an average of 2.5. Sugars are fair at an average of 11.2 Brix. Many fruit are small this year, but size is variable from site to site. Average fruit diameter for sampled gala was 2.7 inches.

Honeycrisp

Fruit were sampled from five locations in Oceana County. Red color improved significantly from last week and is at 81%. We have had excellent coloring weather for Honeycrisp this year. Background color is yellow–green, and fruit are almost mature. At some sites, fruit are considered mature at the recommended maturity rating for starch in Honeycrisp which is 3.5 according to the chart below. Pressure is 14.7 pounds, slightly down from last week. Sugars have also improved and are at 12.2 Brix. Average fruit diameter for sampled fruit this week is 3.1 inches.

Bitter pit development on fruit has been observed in some locations. 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 degrees Fahrenheit 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 five to seven days.

Jonagold

Jonagold fruit were sampled from five locations in Oceana County this week. Red color is at 89%, similar to last week. Background color is light green at 3.7. Fruit firmness is at 18.5 pounds of pressure which is slightly down from last week, but still quite firm. Starch is an average of 2.7, but this varies across sites. Some sites may be ready for harvest for mid- or long-term storage. Sugars improved from last week and are now excellent at 12.9 Brix. Average diameter for sampled fruit is 3.07 inches.

September wonder Fuji

Fruit were sampled at three locations in Oceana County this week. Red color development is at 62%, and background color is light green. Starch is clearing into the cortex with a rating of 2.7, and sugar levels are excellent at 12.7 Brix. Average fruit diameter is 2.8 inches.

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.