MSU Extension Apples

In the west central region, Rome have been harvested at some locations. Harvest of Golden Delicious, Red Delicious and Idared began this week. These varieties as well at Mutsu, Ambrosia and Aztec Fuji were tested for maturity this week (Figure 1).

Weather over the past week has been cooler with temperatures closer to normal for this time of year with highs in the 70s and 60s. High temperatures will remain in the 60s and 70s over the next week with lows in the 50s. Storms brought rain to the region on Sept. 24 and 25. Rain is welcome because it has been so dry; however, excessive rain has led to a slowdown in harvest for some orchards in the region. According to Michigan State University Enviroweather stations, rainfall amounts varied widely across the region where Ludington received 1.12 inches of rain over the past few days, and the Fremont area received 3 inches of rain or more.

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. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted. Samples were collected from two to five locations across Oceana County (Figures 2-3).

For more information about apple maturity testing, review these resources compiled by the Michigan State University Extension tree fruit team.

• Predicted apple harvest dates for 2024 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

Mutsu/Crispin

Fruit were sampled at two locations in Oceana County this week. Fruit are still immature and have had little change in maturity over the past few weeks. There is some blush although fruit are still green. Background color is light green, and firmness is similar to last week at 19.4 lbs pressure. Starch is 2.0, and sugars improved from last week to 13.2 degrees Brix. Watercore was observed at both locations this week.

Golden Delicious

Fruit were sampled at four locations in Oceana County this week. Fruit are mature at some locations and fruit are being harvested this week. Some fruit have blush, and background color is light green. Firmness is the same as last week at 16.9 lbs pressure, and recommended pressure for long-term storage is 17. Starch is 3.6, and fruit are considered mature at a starch rating of 3. Sugars have increased and are excellent at 14.4 Brix according to the table below.

Red Delicious

Fruit were sampled at three locations in Oceana County this week. Fruit are mature at some locations, and red color development is at 98%. Background color is yellow green, and firmness is down slightly from last week at 16.8 lbs pressure. Pressure recommended for long-term storage is 18 lbs. Starch is 2.1, and sugars are 10.6 Brix. Red delicious are considered mature with a starch rating of 2.5.

Idared

Fruit were sampled at five locations in Oceana County this week, and harvest of this variety has begun at some orchards. Fruit are immature on average, but maturity varied from site to site. Red color development is 86%. Background color is light green, and firmness is 17.4 lbs pressure. Pressure recommended for long-term storage is 16 lbs, and fruit are considered mature with a starch rating of 3.5. Starch is rated at 2.6. Sugars improved from last week and are considered good at 12.6 Brix.

Ambrosia

Fruit were sampled at two locations in Oceana County this week. Fruit are mature although there was site to site variation for maturity metrics. Red color development is at 66%, and fruit have a beautiful pink blush. Background color is light green, and firmness is 17.0 lbs pressure. Starch is 3.5, and sugars improved from last week to 12.5 Brix.

Aztec Fuji

Fruit were sampled at three locations in Oceana County this week. Fruit are immature, but they are more mature than expected and ahead of normal this year. Fruit may be mature and ready for harvest next week for long- or mid-term storage. Red color development is 83%, and background color is green. Firmness is 17.5 lbs pressure. Starch is 2.5, and sugar is excellent at 13.1Brix.

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.