MSU Extension Apples

This is the 13th and final maturity apple maturity report for 2022. Reports are sent out every week (usually on Wednesdays), following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

This week in the Grand Rapids area, late season varieties are being harvested or are nearly mature, including Evercrisp, Granny Smith, Braeburn, Rome, and Pink Lady. Overall, fruit size is very good, crop load is excellent, and red color is developing very well. Sugars and pressures have generally been a bit low this season compared to past seasons, likely due to the significant rainfall leading up to harvest. Crop and fruit size has been exceptional, as predicted.

Weather over the past week in the Grand Rapids area has been warm and dry, a much welcome change after all the rain the previous week. High temperatures warmed beginning on Thursday to highs in the 70s Fahrenheit through the weekend and low temperatures were mostly in the 40s F and 50s F. Very little to no rainfall was recorded across the region. 

This week we are seeing another change in weather patterns. A low pressure system moving into our region brought cooler temperatures and rainfall beginning Tuesday afternoon and continuing through Wednesday. Afterward, temperatures will be mostly dry over the next week, and temperatures more moderate, with highs in the 50s F and 60s F and lows in the 40s F to upper 30s F. For the month of November, conditions are expected to be close to average with regard to temperatures and precipitation. 

How to read maturity tables

***The majority of fruit were sampled from untreated blocks (no ReTain or Harvista applied). However, a couple of samples this week included fruit that were treated, as it is becoming more difficult to find untreated fruit.***

Each week, we test apple varieties that are nearing maturity in the Grand Rapids. We are reporting average values for several samples for each variety. Maximum and minimum values are included for the highest and lowest individual fruits evaluated for each, to give a full spectrum of the maturity. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted.

• Predicted apple harvest dates for 2022 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.
• Predicting apple maturity and starch chart from Cornell University
• Starch chart for Honeycrisp Apples developed by Washington State University.

Aztec Fuji

This variety is past mature or past mature in most locations. Red color is very good. Fruit is still very firm, with samples averaging 18.4 lbs. Sugars are much better this week, near 15-16, which is more what we expect with this high sugar variety. Starch clearing indicates fruit is ready for storage, with averages between 5 and 7, depending on location. Watercore was observed in about half of fruit sampled this week.

Granny Smith

Fruit is mature or nearly mature, and being harvested this week. Pressure is still very good, with samples averaging around 18 lbs. Sugars improved just a bit this week and flavor has improved. Starch clearing is progressing, with averages for all samples near 4 this week. Most of the fruit tested this week were producing significant amounts of ethylene.

Law Rome (predicted harvest date: Oct. 11)

Harvest is underway this week in many locations. Red color is excellent. Firmness is still very good, with individual fruit all near 19-20 lbs. Starch clearing was considerably more advanced, with most fruit at 4 or 5 this week. A majority of the fruit tested this week were producing significant amounts of ethylene. This variety is susceptible to red color bleeding in the flesh, and we observed this in about half of fruit tested this week.

Evercrisp

Fruit is mature and ready for harvest in most locations this week. Red color is very in most places. We have noticed that younger trees or trees with poor light tend to have poor or less bright color. Fruit is still very firm, with samples still averaging over 20lbs. Sugars are very good, with 14-15 in all locations tested. Starch clearing was again 4-5 in most individual fruit tested. All fruit tested were producing significant amounts of ethylene. Recommendations from Penn State University are to harvest for long term storage at 4-6 and for direct market at 6-7 starch index. This variety has some sensitivity to CO2 injury in longer storage, which may cause internal browning. This is a very firm variety that stores very well and can benefit from some storage time, which allows for a little softening and development of aromatic flavor compounds. We have observed significant amounts of watercore in this variety this year, including nearly half of fruit tested this week.

Braeburn

Fruit is being harvested this week or next. Red color is improving, and background color lighter. Fruit was still very firm in samples tested this week, averaging approximately 19 lbs. Sugars are still a bit low. Starch clearing is continuing with most fruit tested near 4.5. A little less than half of fruit tested were producing significant amounts of ethylene.

Pink Lady

We sampled three blocks of standard Pink Lady (Cripps Pink) for the second time this week. Some locations are mature and being harvested this week, while others need a bit more time. Red color is very good in most places. Background color is still a bit green in immature fruit but faded to yellow-green in more mature fruit. Sugars were very good and varietal flavor excellent in fruit we tested. Fruit is still very firm, with most fruit over 19lbs. Starch clearing was a bit further along this week, with most fruit between 3-4.

Apple maturity sampling parameters

• Ethylene (% fruits with internal ethylene over 0.2 ppm) = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
• 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: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
• Starch For Honeycrisp: will typically be rated using the standard Cornell SPI 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 Maturity page for regional reports throughout the state and additional resources.