MSU Extension Apples

Apple maturity testing will occur weekly for the northwest 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 Wednesdays.

In the northwest region, growers are actively harvesting Gala and Honeycrisp (Figure 1). Gala was trailing Honeycrisp in maturity, but with the recent and continued warm weather, Gala has caught up. Both varieties are mature now, and growers are concentrating on moving through blocks as fast as their labor can handle. Growers are jumping around between Gala, Honeycrisp and even some processing apple varieties, depending on the requests from processors and packers.

Maturity dates are tracking more closely to last year with varieties being harvested about two weeks ahead of normal. High heat in August and September seems to have significantly advanced growing degree days and maturity later in the season. Monitor blocks to harvest at the optimal maturity stage for each variety and target storage conditions. Communicate regularly with your processors and packers to facilitate proper storage and optimize fruit quality. Do your best to balance harvest with all varieties ripening at a similar time frame.

Color on all apple varieties has been beautiful. These sunny days and cool nights have been helpful for color. At the start of the season, brix levels were low, but we have seen jumps in brix in the past two weeks. Apples are eating much better with the rise in sugar levels; warm and dry days have helped with sugar levels. Despite the hot weather, firmness is holding fairly well. We have seen softer varieties, such as McIntosh, where firmness has declined in the past week. We are testing other varieties where firmness has been holding well given the warm weather.

The warm weather has been pleasant for harvest, but there are concerns about these high daytime temperatures that have been warmer than in normal years. Despite the cool start to the season, we have had ample warm days this fall, and now our growing degree days (GDDs) are closer to the 2024 year, which was the second warmest year on record according to Randy Beaudry’s GDD data (Figure 2).

Currently, the 2025 season is tracking as the year with the 12th highest GDD accumulations. However, we still have warm days predicted into the rest of the week and into next week. These accumulations will change, and the rank may increase if we have continued warm weather. Predictions are forecasting temperatures into the 80s with lots of sunshine for the remainder of this week into the weekend. Many will agree that recent past forecasts for recent days have also been a little off, and the temperatures have been warmer than forecasts have predicted. This warm weather can impact firmness of the fruit, but data suggests most varieties are still firm given the high temperatures.

Warm weather can also affect the storage of apples. In many instances, hot weather reduces the capacity for the fruit to be held as long in storage—the “legs” of the storage time are shortened.

Weather

As mentioned already, the weather has been warm. We have had daytime temperatures in the high 70s. Forecasts are also predicting daytime highs into the 80s over the weekend. The forecasts also predict high amounts of sunshine. There may be some clouds today, Oct. 1, but the next four days are predicted to be sunny and very warm for this time of year. There is some rain in the forecast for Monday, Oct. 6, but there is only a 45% of rainfall. 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.

For more information about apple maturity testing, review these resources compiled by the Michigan State University (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 MSU.
• Predicting apple maturity and starch chart from Cornell University.
• Starch chart for Honeycrisp Apples developed by Washington State University.

Maturity information for northwest Michigan

Honeycrisp

Many growers are into Honeycrisp. Some growers are on their second or third pick. Firmness is holding in Honeycrisp, and many growers have used Retain on this variety. It is apparent where growers have used Retain or Harvista as this fruit is holding its maturity much better than fruit where these products have not been applied. Consider using these plant growth regulators (PGRs) in the future if you have not done so in the past. These PGRs can delay fruit drop, and they can extend the harvest window considerably. At the start of this season, you may have not considered these PGRs with the cooler weather, but these materials can be important when the weather turns warm and maturity ripens quickly.

Color has not been as good as in weeks past, likely due to the first pick apples having already been harvested. Honeycrisp quality has been high. Bitter pit is evident in blocks where the crop load is light, as expected.

Gala

Gala apples have excellent color. There are considerable variations in different Gala strains. Some strains are a deeper, more even red while others have a pink cheek on a yellow background. All strains have colored well this season, and apple color is stunning this year. Gala size has been good across blocks. Firmness is also holding in this variety. The predicted harvest date for Gala in 2025 is Sept. 15, and our normal harvest date is Sept. 18. We are past those dates, and growers are harvesting this variety as fast as they are able.

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.
• 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 Pocket Refractometer

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