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 MSU Fruit Team apple maturity calls on Wednesday mornings.

In the West central region, some growers are harvesting Gala and Honeycrisp this week. Jonathan and Jonagold are mature at some locations. Empire and Rome are still immature. Rain will help improve fruit size which has been small at some locations. Cooler nights and sunny days will support red color development. While we’ve had cooler nights in the region, it’s been rainy and cloudy so color should improve with the sunny days that are predicted for the end of the week. Apple size and color is 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 rain across the region over the early part of the week. For the Hart Enviroweather station, 0.17” of rain fell. Rainfall was variable between locations, and Mears received 0.44”, Benona-Shelby received 0.69”, Shelby-East received 0.46”, and Elbridge-Hart received 0.40” of rain over the past few days. Temperatures have fluctuated with lows ranging from the low 40sF to upper 60s since September 9, and high temperatures have ranged from 80F to the upper 60s according to the Hart Enviroweather station. For the rest of the week, temperatures will be more moderate with lows in the 50s and highs in the upper 60s to mid 70s.

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.

Honeycrisp

Fruit were sampled from two locations on September 14 in Oceana County. Fruit were mature at all sites this week, and some growers are harvesting Honeycrisp this week. Other growers are waiting for more red color to develop. Red color development is 65.8%. This was down from last week which was due to sampling. Background color is 2.7 and yellow green. Average pressure was lower than last week and is 14.5 lbs. Average starch rating is 6.6. For these average numbers, fruit could be harvested for short-term storage according to the table below. Sugars improved from last week and are excellent at an average of 13.3 °Brix. Average fruit diameter is 3.1 in. Some bitter pit has developed on trees, especially at sites with large fruit size. Lenticel breakdown was also observed on some fruit.

*For August 18-19, fruit weight, red color, and background color were only evaluated at one site. Firmness, starch, and soluble solids were evaluated at four sites in Oceana County.

Jonagold

Fruit were sampled from five locations on September 14 in Oceana County. Average fruit weight improved from last week and is 165 kg. Average red color development is 86%, and background color is green at 3.5. Fruit firmness was similar to last week at 17.3 lbs, and starch rating is 3.2. Sugars are at 12.4 °Brix. Average fruit diameter was similar to last week at 2.9 in.

Empire

Fruit were sampled from three locations on September 14 in Oceana County. Average fruit weight was 148 kg, and fruit size is still small. Average red color development is 67%, and background color is green at 3.8, similar to last week. Pressure is 18.4 lbs, and starch rating is higher than last week at 2.2 Sugars improved and are at 11.2 °Brix. Average fruit diameter is 2.8 in, and fruit are still immature.

Jonathan

Fruit were sampled from two locations on September 14 in Oceana County. Average fruit weight was 147 kg, and fruit size is still small. Average red color development is 86%, and background color is green at 2.6. Pressure is 17.7 lbs, and starch rating is 3.7. Sugars improved and are at 11.9 °Brix. Average fruit diameter is 2.7 in, and fruit are still immature.

Rome

Fruit were sampled from three locations on September 14 in Oceana County. Average fruit weight was 154 kg, and fruit size is still small. Average red color development is 90%, and background color is green at 4.1. Pressure is 23.0 lbs, and starch rating is the same as last week at 1.4. Sugars improved and are at 11.1 °Brix. Average fruit diameter is 2.8 in, and fruit are still immature.

Ambrosia

Fruit were sampled from two locations on September 14 in Oceana County. Average fruit weight was 155 kg. Average red color development is 44%, and fruit are starting to develop the pink blush. Background color is yellow-green at 2.6. Pressure is 18.9 lbs, and starch rating is 1.8. Sugars are at 11.7 °Brix. Average fruit diameter is 2.8 in, and fruit is 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.