MSU Extension Apples

General comments

October has to be one of my favorite months—it’s right up there with May. I love the new beginning and fresh new start of the spring, but fall harvest is a close second when we get to see the results of a growing season’s hard work. Last week was a big week for Jonagold and Jonathan and those varieties are now complete in all but a few blocks. Golden Delicious are nearly done. Empire are also picked. Some Ida Red harvest is ongoing, and they are coming off quickly too. Growers are moving on to Red Delicious and other varieties in that timeframe and soon after will be Fuji.

Too much rain and a rollercoaster of hot and cold weather is a typical story for October when weather patterns begin to transition from steady summer conditions to full on winter. Soils are saturated with all the recent rains, but harvest continues at a steady pace. The recent hot and humid weather has not been nice for workers, but a cool trend seems to be setting up starting later today.

I have seen a tremendous amount of San Jose scale and woolly apple aphid infestations in the past week of stopping in orchards. It’s the worse I have ever seen in my 30 years of the apple business. Brown marmorated stink bug (BMSB) and other true bugs are all active looking for a place to spend winter and have been very noticeable in the last week. Our BMSB trap numbers are not high overall, but there are some spots with continued catch. Fruit rots and sooty blotch/fly speck are more prevalent this year, not surprisingly given all the rain and humidity since just before harvest began.

Week six of our Grand Rapids, Michigan, area apple maturity sampling continues to show the steadiness of later varieties in their maturity readings. It seems 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

Red Delicious were sampled for the third week and have still changed very little in that time as is typical for Reds. The predicted harvest date for Reds in the Grand Rapids area was Oct. 2, which seems accurate or perhaps a bit on the early side as growers tend to get to them as time allows. Internal ethylene production is still very low with only 10 percent of fruits tested being over the 0.2 ppm level this week. Red color is improving with 91 percent red color. Firmness is still excellent at 16.3 pounds pressure and only slightly down from last week. Starch clearing results average 3.2, which is up from last week’s two readings, indicating Reds are now very much in the window for long-term CA storage. Brix is about the same at 11.6 and should improve in the next week but is very normal for Red Delicious.

Our second week of Ida Red sampling shows very little movement forward for this variety, but they could be harvested at any time for processing or long-term CA storage. The predicted harvest date is Oct. 9 for 2018, which seem to be a good target.

Our second week of Cameo sampling shows forward movement in all maturity parameters. Internal ethylene jumped from 10 percent fruits last week to 50 percent fruits this week with internal ethylene over the 0.2 ppm climacteric. Red color is changed very little, but very good at 86 percent. Fruit firmness is excellent at 16.5 pounds, a decrease from last week’s 18.6 pounds pressure. Starch clearing is up from 3.1 last week to 4.3 this week. Brix are very good at 12.8 and only up slightly from 12.6 last week. Cameo come in around Red Delicious timing, so keep a close eye on them—they are just now entering the optimum harvest window for long-term CA storage.

Our Rome samples have changed very little from last week’s fruit. Our predicted harvest date for Rome in the Grand Rapids area is Oct.14 and that date will be a good target to get started with harvest for any long-term CA needs. Internal ethylene is not yet present in our sampled fruit. Color is very good at 83 percent red color, down only slightly from last week’s 89 percent. Background color indicates the start of a mature fruit at 1.5, which is a decrease in green color from last week’s 3.1 average. Firmness is similar to last week and is still excellent at 22.6 pounds on average. Starch reading averaged 2.9 this week, up only a bit from last week’s 2.2. Brix is still good at. Bleeding has not been a widely reported issue yet with Rome, but it could start to show up more commonly in the next two weeks.

Our second week of Fuji sampling shows a movement forward in maturity as expected. Our predicted harvest date is Oct. 25, which should be a good target for peak harvest. Internal ethylene indicates 48 percent of fruits over the 0.2 ppm climacteric, up a bit from last week’s 40 percent. Red color averaged 74 percent this week, down slightly from last week’s 84 percent. Hopefully the upcoming cooler weather and some sunshine will improve red color in Fuji.

Background color averaged 2.1, down a bit from last week’s 2.8 indicating fruit are still green but changing slowly. Firmness is excellent at an average of 18.5 with some fruits as high as 27 pounds pressure. Starch index readings range from 3 to 8 with an average of 6.1. Fuji stains very strangely with iodine and high readings for two weeks from harvest is not that unusual for this variety—starch alone is not a good indicator of maturity in this variety. Brix readings improved from 13.3 last week to 13.9 this week.

Some initial water core is starting to be found in Fuji and it’s quite variable from block to block. There must be rootstock, cultivar and site influences in play with water core in this variety.

We continue to learn 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 it could be ready just before traditional late season Fuji. Kanzi is a high internal ethylene producer and 100 percent of fruits sampled are over 0.2 ppm ethylene, up from 67 percent last week.

Red color is improving with 64 percent red color this week compared to 50 percent last week. The background color numbers average 1.2. Fruit is very firm at 17.8 pounds pressure, which is only down slightly from last week’s 18 pound average. Starch clearing moved forward from 1.9 last week to 3.6 this week. Brix are very good at 13.5 on average and improved from 13 last week.

Evercrisp is another newer variety we don’t yet have a full picture of its maturity profile or a good idea of a predicted harvest date for Michigan. Keep in mind that as trees mature, they settle in to their maturity over time. Young trees could ripen very much differently than when trees are mature. This week’s internal ethylene production is lower for some reason in Evercrisp with 30 of fruits over 0.2 ppm compared to 90 percent last week. Evercrisp has been a high internal ethylene producing fruit over the past several years.

Red color is very much improved from 63 percent red color last week to 83 percent this week. Background color is 2.9 and changed very little from last week. Firmness is very excellent at 22.8 pounds and down from 25.7 pounds last week. Brix readings continue to be very high at 15.1 this week compared to the already high brix of 14.2 last week. Starch Index readings continue to be 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 it is starting to be noticed in samples this week. There are also reports of internal browning, but we are not sure from what yet.

The second week of Pink Lady sampling indicates immaturity, but a shift forward for sure. We are looking at Maslin (hopefully not reverted), which is earlier to mature than standard Pink Lady. Internal ethylene shows 30 percent of fruits over the 0.2 ppm level, up from last week with 20 percent. Red color is improving with 47 percent red color compared to last week’s 42 percent and the variability in color is tightening up. Background color is still quite green with all fruits rated as 3, about the same as last week’s average of 2.4.

Firmness is excellent at 18.6 pounds but decreased significantly from last week’s 24.5 pounds. Starch readings jumped forward from 1.3 on average last week to 3.1 this week. Brix are still good at 12.5 and should improve nicely in the next week or so. Pink Lady (Maslin) is still immature according to the numbers and most likely will need another week to improve.

Braeburn has a predicted harvest date of Oct. 25 and all maturity testing indicates immature fruits still, but with a few changes. Last week, no fruits had internal ethylene over the 0.2 ppm level and this week, 15 percent do. Red color is greatly improved from 43 percent last week to 77 percent this week.

We did test both standard Braeburn and Kumeu Braeburn. Kumeu does have slightly better red color. Background color has moved from quite green last week at 4.2 to less green this week at 2.7. Fruit firmness is still excellent at 20.9 pounds this week, down only slightly from last week’s 21.3 pound average. Starch clearing is changed only slightly from 2.2 last week to 2.4 this week. Brix are good, but not excellent at 11.1 and should improve in the next two weeks greatly.

Granny Smith should have a harvest date similar to Braeburn and the maturity indices show immature fruit at this time with only small movement forward in all maturity readings.

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.