MSU Extension

General apple harvest comments

We have had a good jump in apple maturity in most varieties over the last week. Growers are starting to harvest Jonathan, Jonagold and Golden Delicious. Gala harvest is wrapping up and the final picking of Honeycrisp is also taking place at a few farms. Some varieties are very slow to mature this season, like Empire and Cortland. These two varieties need more time to mature.

As most Honeycrisp blocks have been picked two to three times this season and last week’s testing showed that it was mature, I did not take any Honeycrisp samples for maturity testing this week. However, I did notice that for growers that have a final picking of Honeycrisp that the few apples on the tree have quickly developed a good amount of bitter pit and lenticel rot on much of the remaining fruit.

This is the fourth apple harvest report for the season; I have collected and analyzed apples for the last five weeks. This week, eight apple varieties were sampled and tested for maturity. Red Delicious, Ida Red and Crispin are being tested for the first time this week to get an early read on their maturity.

Our bloom period this spring was early and extended for three to four weeks, resulting in apple maturity being ahead of most growing seasons and that the fruit pollinated over the almost four weeks this spring will be maturing over the same four weeks this fall. This means multiple pickings on most varieties to account for the wider range of apple maturity.

Based on the maturity of most varieties this season, our harvest windows are running a few days earlier than the predicted harvest dates. So far this season there have been a few exceptions to this, like Gala, Empire and Cortland. The predicted harvest dates are listed at the end of this article.

I am a bit concerned about the hot weather that is predicted over the next seven days. It will mean varieties will mature more quickly than usual. Our dry soils will also move fruit maturity faster than normal. Read more details on this topic in “Hot, hot apple harvest concerns” by Michigan State University Extension 

Fruit color remains generally better than average this fall for most varieties, despite the heat of the last week. Many green-skinned apple varieties, like Golden Delicious and Crispin, have a nice blush on them this season. The brix levels have remained high over the last week.

Most growers report their crop is picking out shorter than they predicted. Many farms have added more harvest labor over the last few weeks, combined with the short apple crop, and most farms now have enough harvest labor.

This week, I have seen another big spike in brown marmorated stink bug adults and nymphs in traps. This may be due to soybean fields and other host plants beginning to dry down and thus these plants are less attractive to brown marmorated stink bug feeding. While it appears there are lesser amounts of brown marmorated stink bug damage this season than last, I am seeing limited amounts of fruit damage at many apple farms I have visited over the last month. Continue to look out for brown marmorated stink bug feeding in orchards, particularly on warm afternoons, and damaged fruit as apples are being harvested and graded.

Lastly, I am concerned about the signs of drought stress on apple trees from the long lasting dry soils over much of our region. Signs include wilting of leaves, early leaf yellowing and premature leaf drop. These trees could be negatively affected if we have an early winter or extreme winter cold temperatures.

The table with the normal and 2017 peak harvest dates for apple varieties in east Michigan is included at the end of this report.

Apple maturity at a glance

Individual variety results

Empire was sampled for the third week of the season, and is maturing slower than most other varieties this fall. A few sites and blocks are ready for harvest, but most are not ready and need a few more days to mature. The average starch index moved from 3.0 last week to 3.3 this week, and internal ethylene levels remain low averaging just 10 percent above 0.2 parts per million. Color continues to improve this week to 64 percent, despite the warm weather over the last week. The predicted harvest date for Empire was Sept. 17 for east Michigan, but they are maturing later than this date.

Jonathan was sampled for the second week of the season, and like Jonagold tested last week, they took a strong jump in maturity. Most Jonathan blocks are ready to harvest now, and a few are past the window for long-term storage. The average starch index lept from 1.7 last week to an average of 6.2 this week. The predicted harvest date for Jonathan was Sept. 18 for east Michigan, and several blocks were ready to harvest ahead of this date.

Jonagold was sampled for the second week of the season. Most blocks are ready to harvest, and like Jonathan, a few are testing to be over mature for mid and long-term storage. It is surprising to see how quickly Jonagold and Jonathan have matured over the last two weeks. Keep a close eye on Jonagold maturity. The average starch index is 4.9, down from last week; however, my sample size ramped up this week and includes some blocks that are traditionally later to mature. Also, note the range of starch index from 2.5 to 7.3. The predicted harvest date for Jonagold in east Michigan was Sept. 18.

Cortland was sampled for the second week of the season and, like Empire, is slow to mature this season. They are not ready to harvest yet; I expect they will need five to seven more days to mature. The predicted harvest date for Cortland is today, Sept. 20, for east Michigan. The average starch index is down slightly this week to an average of 2.0.

Golden Delicious was sampled for the second week of the season, most blocks sampled were the Smothee strain. Some blocks are eating very well and are ready to harvest now, while other sites need a few more days to mature. The average starch index rose from 1.3 last week to 3.6 this week. However, the spread of maturity from farm to farm is very wide, from 1.0 to 6.8. The predicted harvest date for east Michigan for Golden Delicious is Sept. 25, but most blocks will be ready to harvest well ahead of this date.

Red Delicious was sampled for the first week of the season to get an early read on its maturity. Based on these first-week results, it is not ready to begin harvest. The average starch index is only 1.6; they are eating very green. The predicted harvest date for Red Delicious is Sept. 28 for east Michigan, which is eight days from today. Let’s see what next week’s data looks like to dial in this harvest date closer.

Ida Red was sampled for the first week of the season, also to get an early read on its maturity. Based on these first-week results, it is not ready to begin harvest. The average starch index is only 1.6. The predicted harvest date for Ida Red for east Michigan is Oct. 2, which is 12 days from today. Let’s see what next week’s data looks like before making a harvest projection date.

Crispin or Mutsu was sampled for the first week of the season to get an early read on its maturity. Based on these first-week results, it is not ready to begin harvest. The average starch index is only 1.8. The predicted harvest date for Crispin is Oct. 6 for east Michigan, which is 16 days from today. Here again, let’s see what next week’s data looks like.

Predicted peak fresh market apple harvest dates

Each year we publish predicted harvest dates for three varieties for many locations across the state. This year's “Predicted 2017 apple harvest dates” were published July 25. The table below has been expanded to include more apple varieties and it lists only one date for the entire east Michigan region, which is hard to do! The information in the “Predicted 2017 apple harvest dates” article lists the bloom and harvest dates for Deerfield and Romeo, Michigan. You can adjust your predicted harvest dates based on your bloom dates or make adjustments to this expanded list based on the typical harvest dates at your farm. These predicted harvest dates are based on a long-established formula using the bloom date and temperatures for 30 days post-bloom.

These dates are an estimate and will be affected by the apple strain, rootstock, crop load, fertility, soil type, and other factors including current weather. I believe our actual harvest dates may be a few days ahead of these predicted harvest dates for most varieties. Keep a close eye on the weekly apple harvest updates for possible revisions of these dates.

Looking for more? View Michigan State University Extension's Apple Maturity page for regional reports throughout the state and additional resources.

The East Michigan Apple Harvest Report is produced by Bob Tritten, district fruit educator in Flint, Michigan. Email: tritten@msu.edu; Office phone: 810-244-8555; Cell: 810-516-3800; and Fax: 810-341- 1729. Special thanks to the three orchards that allow me to harvest fruit for analysis every Monday during the apple harvest season: Spicer Orchards in Hartland, Erwin Orchards in South Lyon and Hy's Cider Mill in Romeo. Thanks to so many other orchardists that I collect fruit samples from to include their varieties on more of a random basis. Lastly, thanks to the Post-Harvest Lab in the Department of Horticulture at Michigan State University that provides the quick and very accurate analysis of so many apple samples in the fall. Randy Beaudry and his students do a fantastic job and are a valuable part of our Apple Maturity Team.