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.

Honeycrisp and Gala harvest are underway. Honeycrisp matured quicker than expected over the past week. Gala maturity advanced since last week and is now mature just after Honeycrisp for most locations. Apple maturity for Gala blocks that were treated with ReTain have also advanced since last week and are mature with an average starch rating of 3 compared to nontreated blocks, which have an average starch rating of 4.5.

McIntosh are mature and have been harvested at some locations. Jonagold is ready to harvest for long-term storage. Empire is still immature but will be ready for harvest shortly.

For later maturing varieties, a product like aminoethoxyvinylglycine (AVG; ReTain) can be used, and applications at 28, 14 or seven days before harvest are recommended. For a 1-MCP product (Harvista), applications are recommended closer to harvest at seven or three days.

Weather over the past week has been warmer with low temperatures in the mid- and upper 50s and highs in the 70s and 80s across the region according to the Hart Enviroweather station. Daytime temperatures will cool slightly through the end of the week, and weather conditions are forecasted to be warm and dry through Friday. There will be slight chances of rain this weekend. Dry conditions have made fruit size challenging this season, particularly with gala strains and apple blocks that are not irrigated.  

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

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 is similar to last week at 83%. Background color is yellow at 1.6. Fruit firmness is down slightly from last week at 17.2 pounds of pressure. Starch is an average of 4.1. Fruit are mature and could be stored for mid-term controlled atmosphere (CA) storage (recommended pressure is 17 pounds). Sugars are good at an average of 12.5 Brix. Many fruit are small this year, but size is variable from site to site. Average fruit diameter for sampled gala was similar to last week 2.73 inches.

Honeycrisp

Fruit were sampled from three locations in Oceana County. Red color was similar to last week. We have had excellent coloring weather for Honeycrisp this year. Background color is yellow-green, and fruit are mature. Pressure is 13.7 pounds, slightly down from last week. Sugars continue to improve and are at 12.6 Brix. Average fruit diameter for sampled fruit this week is 3.2 inches. Fruit should be stored according to pressure recommendations and starch ratings in the tables below. Fruit with lower pressure should be packed and sold sooner compared to fruit with higher pressure. Recommended pressure for CA storage is 15 pounds or higher.

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 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 five to seven days.

Jonagold

Jonagold fruit were sampled from four locations in Oceana County this week. Red color is similar to last week at 88%. Background color is yellow-green at 2.5. Fruit firmness is at 17.9 pounds of pressure, which is slightly down from last week, but still firm. Starch is an average of 4.1, 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 13.9 Brix. Average diameter for sampled fruit is similar to last week at 3 inches.

September Wonder Fuji

Fruit were sampled at three locations in Oceana County this week. Red color development is at 78%, and background color is light green. Pressure is similar to last week at 15.9. Starch rating advanced from last week and is 5.3. Fruit are mature and ready for harvest and CA storage. Sugar levels continue to improve and are excellent at 13.7 Brix. Average fruit diameter is 3 inches.

Empire

Fruit were sampled at two locations in Oceana County this week. Red color development is at 78%, and background color is green. Starch is clearing into the cortex with a rating of 3.2, and sugar levels are good at 12.1 Brix. Average fruit diameter is 2.7 inches. Empire are almost mature.

Ambrosia

Fruit were sampled at two locations in Oceana County this week. Red color development is at 53% and fruit have a very nice blush. Background color is light green. Starch is just starting to clear into the cortex with a rating of 1.8, and sugar levels are excellent at 13.0 Brix. Average fruit diameter is 2.9 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.