MSU Extension

General apple harvest comments

With the heat of last week and continued drought at most fruit farms, we have had a good jump in apple maturity in most varieties over the last week. Growers are finishing harvest of Jonagold and Empire, and are working at Golden Delicious harvest. Some early maturing sites are also seeing that Ida Red, Northern Spy and Crispin are quickly nearing maturity. Red Delicious is also very close to beginning harvest. Most Cortland blocks have been harvested.

I am a still concerned about the impact on apple quality from the hot weather we experienced over the last week. This fruit may not have the “legs” in storage that growers are accustomed to. Heat and dry soils also caused a great amount of premature leaf drop in most varieties over the last week.

There has been a fair amount of mild water core development in Jonagold and Red Delicious in the last week. Some varieties are also a bite loose, causing a moderate of fruit drop over the last week.

This is the fifth apple harvest report for the season. I have collected and analyzed apples for the last six Mondays. This week, 10 apple varieties were sampled and tested for maturity, with Northern Spy, CandyCrisp, Fuji and Autumn Gala being tested for the first time 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. Most growers continue to report their crop is generally picking out shorter than they predicted.

For the third week in a row 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 drying down early due to drought and thus these plants are less attractive to brown marmorated stink bug feeding. While it appears there is lesser amounts of brown marmorated stink bug damage in apples this season than last, there are limited amounts of fruit damage at many apple farms. Continue looking 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

Empire was sampled for the fourth week of the season, and as I shared in last week’s report, needed just a few more days to mature. So, most blocks have been harvested in the last week and thus my sample size was limited this week.

The internal ethylene levels of fruit over the 0.2 parts per million (ppm) trigger point jumped up to 70 percent this week. The average starch index moved from 3.3 last week to 6.4 this week. The predicted harvest date for Empire was Sept. 17 for east Michigan, but for some reason Empire matured later than this date.

Jonagold was sampled for the third week of the season, and like Empire, most blocks have been harvested, so my sample size was limited to just a few blocks. Most blocks were ready to harvest last week. The average starch index was lower this week, dropping from 4.9 to 3.3 this week, but this was a reflection of the few blocks that were unharvested are on later maturing sites. The predicted harvest date for Jonagold in east Michigan was Sept. 18.

Golden Delicious was sampled for the third week of the season; most blocks sampled were the Smothee strain. Goldens have matured well in the last week and results of testing this week show they are now ready to harvest. Most 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 3.6 last week to 4.6 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 second week of the season. Based on the results of testing done this week, Reds are close to being ready to harvest, but still need a few more days to mature. The percentage of fruit with internal ethylene over 0.2 ppm almost tripled to 57 percent. The average starch index rose from 1.6 last week to 3.5 this week. The predicted harvest date for Red Delicious is Sept. 28 for east Michigan, which is tomorrow. So, it appears Reds will be ready a few days after this date. Remember that 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 second week of the season. Based on this week’s test results, Ida Reds are about three to five days away from being ready to harvest. The average of fruit above the 0.2 ppm level of internal ethylene rose from 40 percent last week to 90 percent this week, with the average starch index up from 1.6 last week to 3.6 this week. The predicted harvest date for Ida Red for east Michigan is Oct. 2, which is five days from today, so it will be ready to begin harvest right at this predicted harvest date.

Northern Spy was sampled for the first week of the season to get an early read on its maturity. Based on these first week results, some blocks are ready to harvest. All of the fruit tested above 0.2 ppm of internal ethylene, which is typical for Northern Spy. The average starch index is 4.6. The predicted harvest date for Northern Spy is Oct. 2 for east Michigan, so many blocks will be ready to harvest ahead of this date.

Crispin or Mutsu was sampled for the second week of the season. Based on this week’s test results, some blocks are ready to harvest and others need more than a week to mature. There is a widespread in Crispin maturity from farm to farm, so check your Crispin blocks today to be sure you don’t miss harvest if you are one of these early maturing sites. The average starch index rose from 1.8 last week to 4.6 this week. The predicted harvest date for Crispin is Oct. 6 for east Michigan, so depending on your site, some are very early and others appear to close to this date.

CandyCrisp 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 close but not quite ready to begin harvest. The average starch index is 3.0. The expected harvest date for CandyCrisp is five days after Red Delicious, or Oct. 3 for east Michigan. I think this date will be close.

Fuji was sampled for the first week of the season to get an early read on its maturity. Based on these first week results, some blocks may be ready to harvest and others might need several more days to mature. There is a good amount of fruit (75 percent) with internal ethylene levels above 0.2 ppm. The pressure tested at an average of 18.6 pounds, which seems low for a variety with a predicted harvest date of Oct 18. The starch index levels averaged 6.9. The apples eat on the green side. I need to hear back from the lab at MSU to be sure they are reading the starch levels correctly. I want to get another week of data next week and increase my sample size to get a better read on Fiji maturity. It seems odd for Fuji to be ready to harvest so early.

Autumn Gala was sampled for the first week of the season to get an early read on its maturity. The average starch index is 6.4. Autumn Gala’s harvest window generally opens about 12 days after Redchief Red Delicious, or Oct. 10 for east Michigan. Based on this first week of testing, it is ready to begin harvest. However, based on the typical harvest date of Oct. 10, it should not be ready yet. As in the case of Fuji, I want to see another week of testing to tell me more about Autumn Gala maturity.

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.