MSU Extension Apples

General comments

Harvest in the Grand Rapids, Michigan, area is over the halfway point with great quality and good size being reported. Gala harvest is complete and Honeycrisp harvest is nearly complete. Golden Delicious harvest continues with some blocks waiting for dry conditions to pick in. This week has been a big week for Jonagold harvest. Recent rainy days have slowed harvest a bit and should not hinder progress overall.

Week five of our Grand Rapids area apple maturity sampling shows the steadiness of later varieties in their maturity readings. It seems that the earlier varieties have great variability related to weather conditions, whereas later varieties are more reliable as to what to expect. A good chart to refer to can be found in “Checking apple maturity: What to look for” from Michigan State University Extension, where guidelines for firmness and starch can be found.

Apple variety sampling results

Empire are still in the long-term controlled atmosphere (CA) storage window this week and they are shifting to a more mature level quite slowly this year. Our predicted date for Empire peak harvest in the Grand Rapids area was Sept. 24 and it appears this date was on target this year. Internal ethylene is still very low with only 10 percent of fruits over the 0.2 ppm climacteric.

Red color improved from last week’s 66 percent to 82 percent red color this week. Firmness is excellent at 17.2 pounds pressure. Starch index readings for this week are higher at an average of 3.1 and Brix have improved a bit from 12.2 last week to 12.4 this week.

Jonagold harvest started last week and many have come off in the last week. The predicted harvest date for Jonagold was Sept. 26 and they are still in the long-term CA storage window. Internal ethylene is up from last week’s samples with 20 percent of fruits now over the 0.2 ppm climacteric.

Red color continues to improve, up from 62 percent red color last week to 82 percent this week. Background color is more yellow than green with an average of 2 this week compared to 2.4 last week. Firmness continues to be very good with an average of 16,2 pounds, which is down from last week’s 17.4 pounds. Starch levels are about the same at 4.2 this week and probably not a good indication of maturity by itself this year. Brix levels continue to improve at 13.4 this week compared to 13.1 last week.

This is the fourth week of sampling Golden Delicious. The predicted harvest date for peak harvest in the Grand Rapids area was Sept. 28 with harvest beginning last week. Growers have been waiting for drier conditions to harvest Goldens to lessen the risk for bruising. Firmness is very good at 16 pounds compared to 15.7 pounds last week. The starch clearing shows an average of 3.9 this week compared to 5.7 last week. Brix are slightly improved from 13.8 last week to 14.4 this week.

Golden Delicious continue to hold in the long-term CA storage window in the general Grand Rapids area and they could change quickly if warmer weather moves in. Fruit size and finish are very good in Goldens this year.

Red Delicious were sampled for the second week and they have changed very little in that time. The predicted harvest date for Reds in the Grand Rapids area is Oct. 2, which should shape up to be an accurate target and your will get to them as time allows. Fruits are producing internal ethylene, but in very low amounts and no fruits were over the 0.2 ppm level this week.

Red color is very good to excellent depending on the strain. Firmness is excellent at 17.6 pounds pressure. Starch clearing results average 3 indicating they are still on the immature side. Brix is quite low as is usual for Red Delicious at 11.9 – improved from 10.4 last week.

Nova Spy was missed in our sampling last week and they have improved greatly in those two weeks. They are now ready for harvest as they should have a harvest date around or just after Golden Delicious in the Grand Rapids area.

We sampled Ida Red for the first time this week and it is immature at this time. The predicted harvest date is Oct. 9 for 2018. Red color is good but needs some improvement. 20 percent of fruits have over 0.2 ppm internal ethylene. The background color is still on the green side with an average reading of 2.9. Firmness is excellent at 16.6 pounds. Starch clearing is very low at 1.6 on average and brix are not too bad at 12.8.

Cameo is not a common variety overall, but we see more planted each year. Our sampling this week showed 10 percent of fruits with internal ethylene over the 0.2 ppm climacteric. Red color is very good at 87 percent and will improve in the next week. Fruit firmness is excellent at 18.6 pounds pressure. Starch readings averaged 3.1. Cameo come in around Red Delicious timing, so keep a close eye on them as they are most likely within a week of the optimum harvest window for long-term CA storage.

Another newer variety is Crimson Crisp, which we sampled for the first week. This variety tends to have fruits with a high percentage (80) over the 0.2 ppm climacteric, which will enhance the ripening process. The red color on this variety is excellent averaging 91 percent. The background color is on the low side at 1.4, which indicates maturing fruit.

Fruit firmness is excellent at 21.8 pounds on average. Starch Index readings are still low at an average of 2. Brix readings are very good to excellent at 13 to 15 across the sample. Keep a close eye on Crimson Crisp – they too come in around the Red Delicious timing.

Our predicted harvest date for Rome in the Grand Rapids area is Oct. 14 and they need at least another week or two to get there. Internal ethylene is not yet present in our sampled fruit. Color is very good at 89 percent red color. Background color indicates immaturity at 3.1. Firmness is still excellent at 22.5 pounds on average with some fruits having pressure as high as 27 pounds. Starch readings show 2s and 3s. Brix is rather good at 13 for this early in the season for Rome. Bleeding has not been a widely reported issue yet with Rome.

This was our first week to sample late season Fuji strains. Our predicted harvest date is Oct. 25, which should be a good target for peak harvest. High levels of internal ethylene (40 percent of fruits over 0.2 ppm) are present, which isn’t unusual for Fuji. Red color averaged 84 percent with a range of 60 to 95 percent. Color needs some improving. Background color averaged 2.8 indicating fruit are still green. Firmness is excellent at an average of 19.2 pounds. Starch index readings range from 2 to 7 with an average of 4.4, which might seem high but is typical for Fuji two weeks from harvest. Brix readings averaged 13.3 which is pretty good for this time.

Very little to no water core is being found Fuji at this time, which is a bit surprising given the high amounts of rainfall in the last month. Keep an eye out for water core development and harvest accordingly.

We are still learning about the maturity profile for Kanzi, which is cross between Gala and Braeburn. It is thought to be ready sometime around Fuji timing and the data from this first week of sampling seems to indicate a later date for harvest.

Evercrisp is another newer variety that we don’t yet have a full picture of its maturity profile or a good idea of a predicted harvest date for Michigan. Just like last year, the internal ethylene readings show a high number of fruits (90 percent) over the 0.2 ppm climacteric. We saw similar data in 2016 as well. Red color is good at 63 percent and needs improving. Background color is averaging 2.4. Firmness is very excellent at 25.7 pounds. Brix readings are also excellent for this time at 14.2. Starch Index readings are quite variable.

Evercrisp is a cross between Honeycrisp and Fuji. Like Fuji, the starch staining is very different than other apple varieties – it doesn’t stain very darkly and can be hard to read. Water core can be an issue with Evercrisp and none was noted in this week’s samples.

We added Pink Lady to our sampling this week. We are looking at Maslin, which is earlier to mature than standard Pink Lady. Internal ethylene shows 20 percent of fruits over the 0.2 ppm level. Red color is quite variable ranging from 10 to 60 percent and should improve in the next two weeks. Background color is still greenish at 2.4 for an average.

Firmness is excellent at 24.5 pounds. Starch readings are very low averaging 1.3. Brix are good at 13 and should improve nicely in the next two weeks. Pink Lady (Maslin) is still immature according to the numbers and most likely will need another two weeks to improve.

Braeburn has a predicted harvest date of Oct. 25 and all maturity testing indicates immature fruits.

Granny Smith should have a harvest date similar to Braeburn and the maturity indices show immature fruit at this time.

Apple maturity sampling parameters

• % 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
• 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.
• 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.