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.

Premier Honeycrisp harvest has started in the region, and growers with Minneiska are testing for maturity. We will expand to test Gala and regular Honeycrisp next week.

Weather

Last week’s weather was reminiscent of late fall. Conditions were almost Halloween-like in northern Michigan. We had high temperatures in the mid-50s with winds and rains; low temperatures dropped into the high 40s. These temperatures are more typical for later in the season, and they seemed particularly shocking following a warm long Labor Day weekend. This weekend saw more of the same with cooler temperatures and intermittent sunshine and rain, and some of the rainfall was heavy at times. There were some reports of isolated hail on Saturday night (Sept. 6).

This week’s weather forecast is more seasonable with daytime highs in the 70s and nighttime temperatures falling back to mid-50s—weather that is more familiar for this time of year. These sunny days and cool nights will continue to improve apple color.

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

Premier Honeycrisp

Fruit were sampled from one location on Sept. 8 in Leelanau County. Individual samples represent fruit closest to maturity or “first pick” fruit in each block. Red color has improved with warm daytime temperatures and cool nighttime temperatures. Starch rating average is 4.2. Pressure is 18.4 pounds on average and Brix are up slightly from last week at an average of 12.1. Other growers with Premier Honeycrisp have begun harvest, and most of this fruit will go for fresh market.

A note about Premier Honeycrisp: Wait for acceptable varietal flavor and color to develop before picking. Picking fruit and getting it into the market early seems like an edge but will hurt repeat sales of this strain and standard Honeycrisp.

Minneiska

Minneiska apples were sampled from four orchards: two in Antrim County and two in Leelanau County. Counties with this variety to the south have already harvested this variety. All growers with this variety have started to harvest this week. There is some color variability between blocks, but we have observed some beautiful Minneiska with excellent color in many blocks. Again, the cool nights have really put a red cheek on this variety.

Background color is brighter yellow compared with last week. Starch averages from the four orchards are 4.1 with a range of 2-8, and sugar levels are at 12.9 Brix. The brix on most of the fruit was quite high, but there was a range of sugar levels from 11.9-14.7. The firmness only dropped 0.6 pounds from last week. There are some beautifully colored fruit on the trees and in the bins.

Honeycrisp

Honeycrisp growers are waiting patiently for this variety to mature, and it is closer this week but still have some time go to before it is mature, even for longer term storage. We see some variability in color, likely do to strain but also due to tree canopies in the different orchards. More growers are summer pruning to get more color on the fruit, and this technique is apparent when we run samples from different orchards with different management strategies. Size of the fruit in most orchards is quite good this year where growers dialed in their thinning. We have seen some orchards where the trees are overcropped, and the fruit size is obviously smaller.

The Honeycrisp predicted harvest date is Sept. 23, and the results from this sample suggest that this date is close. This week, we sampled five Honeycrisp orchards. There is some variability in maturity, ranging from a starch index reading of 3.4 down to 1.4. There is also some variability in color, from 49 to 85%. Brix levels are still quite low across all blocks with an average of 10.9.

Gala

Gala apples are also starting to color, and we can see differences in color with the different strains of this variety. However, overall color on Gala is improving, and we expect to have excellent color this year if the weather conditions are consistent with what they are predicting. Size on Gala also seems to be good. Sometimes, we struggle with size on Gala in our sandy soils, even with irrigation. We have had ample rainfall this year, and Gala size has benefited from this extra rain. Gala is a way off from maturity, and we could see some slow development with our cooler overnight temperatures. The predicted harvest date for Gala in 2025 is Sept. 15, and our normal harvest date is Sept. 18. From this initial sample of Gala, we still have time before Gala are ready this season, and it is doubtful that most orchards will be ready for harvest in six days.

Gala color is good for this time of the season, and this week, we had an average range of color from 59-97%. Gala are still very firm as they have some time to go, and we had an average of 22.5 pounds in firmness this week; all samples were consistent in firmness. We are still testing in the ones and barely two (1-2) for most fruit samples for starch clearing.

McIntosh

This variety is harder to find to test for maturity in the region. The three orchards we tested are obviously different strains of McIntosh as apples from two orchards are almost completely red while one sample of the older strain on big trees are almost all green. Growers with different strains of this variety should not look at the average of color in our data.

In addition to extreme variability in color, there are noticeable differences in firmness, and McIntosh is a variety where we are challenged to maintain firmness. In the three samples from this week, the firmness ranges from 17.8 up to 20.8. This variety is not yet mature, and the range of starch removal ranges from 1.4-3.1 (average: 2.2) from this sample size. Brix is an average of 10.6.

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.