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 still harvesting Premier Honeycrisp. Many growers are finished with first pick and are starting or completing their second pick now. Color has been variable across the board, and lots of fruit is under color compared to other years. Growers with the variety Minneiska are wrapping up harvest. Apple size is variable across orchards, but again this week, size does seem to be improving. Color for all varieties is also improving, but color continues to lag in all varieties. All varieties we tested this week are moving toward maturity, as would be expected. At the start of the week, there was rain in the forecast for many days, but today, the forecast is predicted to be cloudy with small chances of rain.

Weather

The weather forecast had been predicting chances of rain for the next 10 days, but it does vary from forecast to forecast, and the percent chance of rain has a big range: 10-85% depending on the day and weather forecast. Clouds seem to be in the forecast for most days, and this situation will not help color fruit. Weekend temperatures were nice and were good for apple maturity and color. Daytime highs were in the seventies and overnight temperatures dropped into the mid-50s. Yesterday, the temperature started out in the mid to low 40s, the coolest start to a day yet this season.

Cooler weather is in the forecast for the coming week. Daytime highs are topping out in the mid-60s. We did receive rainfall on the evening of September 14 into the morning Sept. 15; the station recorded 1.5” of rain. This long rain was accompanied by windy conditions. Windy conditions are expected to continue throughout September 15. The S.S. Badger is discontinuing car ferry service across Lake Michigan today, September 15, due to dangerous conditions and waves reaching 20ft.

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 are showing an increase in starch readings this week. Apple color has also improved. Be sure to test maturity block by block.

Premier Honeycrisp

We did not sample Premier Honeycrisp this week as most growers with this variety have started and/or finished harvest. The color on some previous samples of Premiers was not good, and growers were continuing to wait on color. However, the fruit sampled last week were testing at an average of 6.4 for starch, signaling that this fruit is ripe and needs to be harvested, even if color is not optimal. Fruit that are still not harvested this week are likely to be overmature or approaching overmature.

Gala

Gala fruit were sampled from five locations on September 14. Red color is at 85%, which is up from the 73% last week. Fruit firmness is similar to last week at an average of 20.4 lbs of pressure, and this average was down compared to 22 from last week. Starch is an average of 2.4, which is numerically lower than last week: 1.3. Sugars are an average of 11.1 °Brix, and these numbers are higher than the 10.2 °Brix from last week. Again, similar to last week, Gala size looked better this week compared to past week. Gala color has also jumped over 10% compared to last week.

Honeycrisp

Fruit were sampled from seven locations on September 14. Fruit are immature, but the maturity has advanced slightly since last week. Growers need to keep an eye on this variety because other parts of the state have been reporting that this variety has been moving from under mature to over mature very quickly, particularly without change in color. Average pressure has remained consistent compared to last week, and we reported an average of 18.5 lbs for this week.  Sugars are at 11.0 °Brix this week, and again, this was the same average number from last week. Again, a reminder to growers, Honeycrisp in other parts of the state have moved quickly in maturity—growers need to be watching the variety closely so they the fruit do not go from under-mature to overmature in a short amount of time. Honeycrisp starch removal was an average of 2.4 last week, and we had an average of 2.9 this week. Color on Honeycrisp still low, and we did not see much of an improvement in this parameter from last week. The weather forecast is predicting cooler weather but little sun, so color may be difficult to improve over the next week.

McIntosh

We tested four samples of McIntosh in Leelanau County this week. Color on all apples tested is marginal, and the background color is still green. There is the classic McIntosh flavor when you bite into this variety, but the fruit is still starchy. However the fruit is maturing, and we had an average starch removal 2.6 this week compared to 1.5 last week. Firmness is similar to last week: 19 lbs last week and 18.3 lbs this week. Brix also seems slow to increase in this variety; there was no increase in brix readings from last week until this week, for the second week in a row.

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.