MSU Extension Apples

Apple maturity testing will occur weekly for the west central 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.

In the west central region, some growers are harvesting Jonagold and Empire this week. Golden Delicious are mature at some locations. Rome and Red Delicious are still immature. Honeycrisp and Gala harvest will finish this week for many growers, so they are not included in this week’s report.

Rain over the weekend helped improve fruit size, which has been small at some locations. We’ve had sunny conditions the past few days, which has enhanced red color. Apple size and color are variable across orchards and even within a tree.

Use preharvest management tools as needed to harvest fruit in a timely manner. Products like ReTain or Harvista can slow or pause fruit maturity and prevent premature fruit drop.

Weather

Storms brought gentle rain across the region over the past week. For the Hart Enviroweather station, 0.79 inches of rain fell since September 16. Temperatures have fluctuated with lows ranging from the low 40sF to upper 60s, and morning temperatures  were in the upper 30s on September 23.

Fall has settled in with cooler temperatures. High temperatures have been consistently in the 60s according to the Hart Enviroweather station. For the rest of the week, temperatures will be cooler with lows in the 40s and highs in the 60s.

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 2-7 locations in 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 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 West Central region

Note that apple maturity is occurring earlier than normal this season with variability between orchard blocks and sites. Be sure to test maturity block by block for each variety. Young trees are maturing more quickly than older trees, and bitter pit and lenticel breakdown were observed again this week.

Jonagold

Fruit were sampled from three locations on September 21 in Oceana County. Average fruit weight improved from last week and is 169 g. Average red color development is 88%, and background color is light green at 3.2. Fruit firmness declined this week to 15.7 lbs, and starch rating is 4.7. Fruit were mature at all sites tested. Sugars are at 12.8 °Brix. Average fruit diameter was similar to last week at 2.9 in.

Rome

Fruit were sampled from two locations on September 21 in Oceana County. Average fruit weight was 164 g. Fruit size is getting larger although it is still small at some locations. Average red color development is 95%, and background color is yellow green at 2.7. Pressure is 25.0 lbs, and the difference between last week’s and this week’s readings were due to sampling sites. Starch rating is 2.4. Sugars improved and are at 11.6°Brix, and average fruit diameter is 2.8 in. Fruit are still immature; however, some growers may harvest toward the end of this week to pick mature fruit before red color appears in the flesh.

Golden Delicious

Fruit were sampled from four locations on September 21 in Oceana County. Average fruit weight is 170 g. A slight blush is present on the sun side of fruit and covers 24% of the surface. Background color is yellow green at 3.4. Pressure is 16.8 lbs, and starch rating is 3.2. Sugars are at 13.3 °Brix. Average fruit diameter is 2.8 in, and fruit are almost mature.

Red Delicious

Fruit were sampled from three locations on September 21 in Oceana County. Average fruit weight was 148 g. Average red color development is 91%, and background color is yellow at 1.9. Pressure is 18.0 lbs, and starch rating is 1.9. Sugars are at 11.0 °Brix. Average fruit diameter is 2.75 in, and fruit are still immature.

Crispin/Mutsu

Fruit were sampled from three locations on September 21 in Oceana County. Average fruit weight was 274 g. Fruit are starting to develop the pink blush at 19% on average. Background color is green at 3.8. Pressure is 19.9 lbs, and starch rating is 1.7. Sugars are at 11.7 °Brix. Average fruit diameter is 3.24 in, and fruit are still immature. There is some blister spot that was observed at a couple sites for this variety. This is a bacterial disease, and management is needed during the three weeks after petal fall.

Idared

Fruit were sampled from four locations on September 21 in Oceana County. Average fruit weight was 166 g. Average red color development is 71%, and background color is green at 3.2. Pressure is 18.4 lbs, and starch rating is 1.5. Sugars are at 11.3 °Brix. Average fruit diameter is 2.95 in, and fruit are still immature.

EverCrisp

Fruit were sampled from two locations on September 21 in Oceana County. Average fruit weight was 177 g. Average red color development is 57%, and background color is green at 3.9. Pressure is 22 lbs, and starch rating is 1.7. Sugars are excellent at 13.1 °Brix. Average fruit diameter is 2.93 in, and fruit are still immature.

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.