MSU Extension

General apple harvest comments

With last week’s heat and continued drought at most fruit farms, the typical order of apple variety harvest is different than most seasons. Also, we have several varieties that are ready for harvest at the same time.

Growers have mostly finishing harvest of Jonagold and are working at harvesting Golden Delicious, Northern Spy, Crispin and Fiji. Ida Red growing on early maturing sites are almost ready to harvest. Red Delicious is very slow to mature this season, as most blocks and strains need more time to mature. Some growers are saying that with good weather they will be done with apple harvest in just over a week’s time.

The impact of the hot weather and drought on apple quality is becoming more evident for our later maturing apple varieties. Fruit seem to have lost moisture and some of its acidity, causing the flavor of some varieties to decline. On the positive side, brix or sugar levels are exceptionally high this week. The bottom line is that these late harvested apples may not have the “legs” in storage growers are accustomed to seeing.

Heat and dry soils accelerated premature leaf drop in most varieties over the last two weeks. A fair amount of mild water core development in Red Delicious is visible, as well as in some Fuji. Some varieties, like Red Delicious, are also a bite loose, causing moderate fruit drop over the last week.

This is the sixth apple harvest report for the season. I have collected and analyzed apples for the last seven Mondays. This week, 10 apple varieties were sampled and tested for maturity, with Rome, Evercrisp and Winesap being tested for the first time to get an early read on their maturity.

For the first time in the last four weeks, I did not see another big spike in brown marmorated stink bug adults and nymphs in traps. As growers are moving through apple harvest, more are finding a limited amount of fruit stinging damage. 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.

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

Jonagold was sampled for the fourth week of the season. Most blocks have been harvested, so my sample size was limited to just a few blocks. Many blocks were ready to harvest late last week, but the remaining blocks are ready to harvest this week. The average starch index rose from 3.3 last week to 5.7 this week. The predicted harvest date for Jonagold in east Michigan was Sept. 18, which was close for many blocks.

Golden Delicious was sampled for the fourth week of the season with my sample size reduced because many blocks have been harvested. Most blocks sampled were still the Smothee strain. Golden Delicious have continued to mature well in the last week and results of testing this week show the remaining blocks are ready to harvest, with some being on the over-mature side. The average starch index rose from 4.6 last week to 5.1 this week. The predicted harvest date for east Michigan for Golden Delicious was Sept. 25, so this predicted date was very close for most blocks.

Red Delicious was sampled for the third week of the season. Based on the results of testing this week, Red Delicious are maturing very slowly this season and most strains are not ready for harvest. They are eating green still and this past week have developed an odd, woody or drier taste. Several other varieties have jumped ahead of Red Delicious in terms of being ready to harvest, like Northern Spy, Crispin and Fiji. So, move on to harvesting these other varieties and then be prepared to come back to harvest Red Delicious next week.

Unfortunately, there is a good amount of drop in Red Delicious in the past week. The percentage of fruit with internal ethylene levels over 0.2 parts per million (ppm) remains about the same as last week at 55 percent. The average starch index dropped from 3.5 last week to 2.7 this week. I saw these starch index levels drop in several apple varieties over the last week. This is mainly due to the extreme heat of the last week and continued drought conditions.

The predicted harvest date for Red Delicious was Sept. 28 for east Michigan, so it appears Red Delicious will be ready several to many days after this predicted date. There are several strains of Red Delicious that mature after the Redchief strain, which is the strain I sampled most often.

Ida Red was sampled for the third week of the season. Based on this week’s test results, Ida Reds are still a few days away from being ready to harvest. They are still eating on the green side. The average fruit above the 0.2 ppm level of internal ethylene rose from 90 percent last week to 97 percent this week. The average starch index dropped from 3.6 last week to 3.2 this week. The predicted harvest date for Ida Red 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 second week of the season. Based on this week’s data, some blocks are 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 also dropped from 4.6 last week to 3.9 this week, the same as Red Delicious and Ida Red. The predicted harvest date for Northern Spy was Oct. 2 for east Michigan, so some blocks were ready before this date and others will be ready after this date.

Crispin or Mutsu was sampled for the third week of the season. Based on this week’s testing results and like Northern Spy, some blocks are ready to harvest and others need and few more days to mature. The average starch index also dropped for Crispin, from 4.6 last week to 3.8 this week. The predicted harvest date for Crispin is Oct. 6 for east Michigan, so depending on your site, some matured early and others appear to close to this date.

Rome was sampled for the first week of the season to get an early read on its maturity. Based on these first week results, it needs more time to mature and is not ready to begin harvest. They eat very green and are almost as hard as a baseball. The average starch index is 3.0, which was higher than I expected. The predicted harvest date for Rome is Oct. 7 for east Michigan, which is this weekend. I don’t think they will be ready to harvest by this date.

Fuji was sampled for the second week of the season. Based on this week’s data, most blocks are ready to harvest and a few may be over-mature and not suitable for long-term storage. Several growers have a good start on Fuji harvest. Almost all (93 percent) of the fruit tested had internal ethylene levels above 0.2 ppm. The pressure tested firm at an average of 18.6 pounds, with the starch index levels also dropping from an average of 6.9 last week to 5.2 this week. The predicted harvest date for Fiji is Oct. 18, so it will mature well ahead of this date.

Evercrisp was sampled for the first week of the season to get an early read on its maturity. The average starch index is 4.0, which was much higher than I expected. 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. So, that predicted harvest date for this early harvest season for most varieties is Oct. 13 for east Michigan. Based on this first week of testing, I feel it is ready to begin harvest. I want to see another week of testing to tell me more about Evercrisp maturity.

Winesap was sampled for the first week of the season to get an early read on its maturity. The average starch index is 1.1. Based on this first week of testing, it is not ready to begin harvest—in fact, it is a long ways off. The predicted harvest date for Winesap is Oct. 27.

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.