MSU Extension

General apple harvest comments

We are at the point of apple harvest where growers are picking and finishing varieties in rapid order. Many growers are thinking they will be done with harvest later this week. Also, with most varieties picking out short, growers are quickly moving through harvest.

Growers have mostly finished harvest of Fuji and Crispin, and are working away on Red Delicious, Northern Spy and Idared. A few blocks of Romes are also ready. Keep an eye on Braeburn, as it is further along than usual for this season.

Most of the region had just over an inch of badly needed rain over the last four days and today, Oct. 11, is bringing even more. We are still far behind in rainfall for August and September.

Water core is being found in several varieties, notably in Red Delicious and Fuji. Some varieties, like Red Delicious and Idared, saw a fair amount of drop in the last week.

This is the seventh apple harvest report for the season; I have collected and analyzed apples for the last eight Mondays. This week, nine apple varieties were sampled and tested for maturity, with Braeburn being tested for the first time to get an early read on its maturity.

Trap catch for brown marmorated stink bug adults and nymphs is lower this week at each of our 12 trapping sites in east Michigan orchards. However, growers are finding them in and around homes and farm buildings on a regular basis. Also, as growers are moving through apple harvest, more are finding a limited amount of fruit stinging damage from this invasive pest. Continue to be on the lookout for brown marmorated stink bug feeding in orchards, particularly on warm afternoons, and for damaged fruit as apples are being harvested and graded.

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

Golden Delicious was sampled for the fifth week of the season. Again this week my sample size was reduced because most blocks have been harvested. All blocks sampled this week were still the Smothee strain.

Golden Delicious have continued to mature well in the last week and are now on the over-mature side and are ready to harvest. The percentage of fruit with internal ethylene levels over 0.2 parts per million (ppm) moved from 55 percent last week to 100 percent this week. The average starch index rose from 5.1 last week to 6.9 this week. The predicted harvest date for east Michigan for Golden Delicious was Sept. 25, so for most blocks this predicted date was very close.

Red Delicious was sampled for the fourth week of the season. Based on the results of testing done this week, most blocks of Red Delicious are finally ready to harvest. Red Delicious have been very slow to mature this season.

There was a good amount of drop in Red Delicious again this past week. The percentage of fruit with internal ethylene levels over 0.2 ppm rose from 55 percent last week to 85 percent this week. The average starch index rose from 2.7 last week to 4.0 this week. The predicted harvest date for Red Delicious was Sept. 28 for east Michigan, so it appears that Reds are ready about 12 days after this date.

Idared was sampled for the fourth week of the season. Based on this week’s test results, Idareds seem to be slow to mature this season and are still a few days away from being ready to harvest. They are eating much better this week. The average of fruit with internal ethylene above the 0.2 ppm level is about the same as last week at 85 percent. The average starch index rose from 3.2 last week to 3.8 this week. The predicted harvest date for Idared for east Michigan was Oct. 2, so it will be ready to begin harvest several days after this predicted harvest date.

Northern Spy was sampled for the third week of the season. Based on this week’s data, it is ready to harvest. All of the fruit tested above 0.2 ppm of internal ethylene again this week, which is typical for Northern Spy. The average starch index rose from 3.9 last week to 5.3 this week. The predicted harvest date for Northern Spy was Oct. 2 for east Michigan, so some blocks were ready before this date and others are ready after this date.

Rome was sampled for the second week of the season. Based on this week’s data, it is ready to begin harvest. The average starch index is up from 3.0 last week to 4.0 this week. The predicted harvest date for Rome was Oct. 7 for east Michigan, so it is maturing a few days later than this predicted date.

Fuji was sampled for the third week of the season and has been a hard variety to determine its maturity this season. Based on this week’s data, most blocks are ready to harvest and a few blocks are over-mature and not suitable for long-term storage. Several growers have harvested Fuji in the last week, and therefor my sample size for testing Fuji maturity was greatly reduced this week compared to the last few weeks.

The pressure actually rose this week to an average of 20.5 pounds, with the average starch index levels also rising from 5.2 last week to 5.7 this week. The predicted harvest date for Fiji is Oct. 18, so it will mature well ahead of this date.

EverCrisp was sampled again this week, but I discovered on Monday, Oc. 9, that the sample I took last week was indeed not really EverCrisp. So, I am starting over with a new set of just one week’s worth of data. All of the fruit tested above 0.2 ppm of internal ethylene, with the average starch index of 3.0.

EverCrisp’s harvest window generally opens about 15 days after Redchief Red Delicious, but this variety is new to Michigan and we are still learning about its maturity. The predicted harvest date for EverCrisp is Oct. 13 for east Michigan. Based on this first week of testing, I feel it is not ready to begin harvest. I want to see another week of testing to tell me more about EverCrisp maturity.

Winesap was sampled for the second week of the season. While the percentage of fruit with internal ethylene levels is high at 90 percent, the average starch index is almost unchanged at 1.0. Based on this second week of testing, it is a long ways off and is not ready to harvest. The predicted harvest date for Winesap is Oct. 27.

Braeburn was sampled for the first week of the season to get what I thought was an early read on its maturity. All of the fruit tested had internal ethylene levels greater than 0.2 ppm. I was also surprised to see the average starch index is 4.2. Based on this first week of testing, it is close to being ready to harvest. The predicted harvest date for Braeburn is Oct. 21. I believe Braeburn will be ready well before this date.

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.