MSU Extension Apples

General apple harvest comments

Most apple growers are getting close to the end of apple harvest, and many are expected to finish by the end of this week or early next week. Farms that offer pick your own sales are holding on to a few varieties until after the weekend and then will finish harvest mid- to late next week.

Most growers have finished harvesting Red Delicious and have started on harvesting Idared, Northern Spy, Crispin, EverCrisp, Fuji and Cameo. In testing done this week Braeburn, Winesap and Enterprise need more time to mature.

This is the eighth and final apple harvest report for the 2019 apple harvest season, with more details on the 10 varieties tested this week. There were no new varieties tested this week.

Special thanks to the four orchards that allowed me to harvest fruit for analysis every Monday during the apple harvest season: Erwin Orchards in South Lyon, Michigan; Hy's Cider Mill in Romeo, Michigan; Spicer Orchards in Hartland, Michigan; and Westview Orchards in Romeo, Michigan. Thanks to so many other orchardists I collected 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 provided the quick and very accurate analysis of so many apple samples this fall. Randy Beaudry and his students do a fantastic job and are a valuable part of our apple maturity team.

Here is the link for the “2019 Apple Predicted Harvest Dates” article that was emailed to area growers as well as published on our Michigan State University Extension Fruit & Nuts News website in August.

Individual variety results

Red Delicious

Red Delicious was sampled for the fifth week of the season, but the sample size was smaller this week as most Red blocks have been harvested. Overall, Reds were very slow to mature this season. The Red strain Redchief was the most common strain I could find for testing this week, as most other strains have been harvested. Most Red Delicious have been harvested over the last 10 days. Based on this week’s data, Red Delicious are ready to be harvested. The predicted harvest date for Red Delicious was Oct. 5, but it was not ready to be picked on that date.

This week, 100% of fruit tested had internal ethylene levels over 0.2 parts per million (ppm) and the pressure has dropped from 17.7 pounds last week to 17.4 pounds this week. The average starch index is up from 2.8 last week to 3.5 this week. We usually look for a starch index for Red Delicious to be around 2.5 to 3.0 for fruit that is intended for long-term storage, but for fresh sales I look for the starch index to be closer to 3.5.

Idared

Idared was sampled for the fifth week of the season are ready to be harvested. Many early sites of Idared were harvested late last week. The average starch index is up from 3.1 last week to 3.7 this week, another nice jump. We usually look for a starch index for Idared to be around 3.5. The predicted harvest date for Idared was Oct. 11, but it was not ready to begin harvest by this date. This week, 67% of the fruit tested had internal ethylene levels over 0.2 ppm and the pressure remains firm at 18.8 pounds. Idareds were ready before many Red Delicious strains.

Northern Spy

Northern Spy was sampled for the fifth week of the season, with just a few blocks tested this week because most blocks have been harvested. Based on this weeks’ data, the few unharvested blocks of Northern Spy are ready to be harvested. The predicted harvest date for Northern Spy was Oct. 12, and most were mature close to this date. Again this week, 100% of the fruit tested had internal ethylene levels over 0.2 ppm. Northern Spy are high ethylene producers, and the pressure is still firm at 22.3 pounds. The average starch index is 3.9. Spy maturity was ahead of Red Delicious this season.

Crispin

Crispin or Mutsu was sampled for the fifth week of the season. Many Crispin blocks have been harvested in the last week. Based on this week’s data, remaining unharvested blocks of Crispin are ready to be harvested. The predicted harvest date for Crispin was Oct. 13, some blocks were mature close to this date and others were several days behind this date. This week, 60% of fruit tested had internal ethylene levels over 0.2 ppm and the pressure was firm at 21.3 pounds. The average starch index is 3.0. I did not find additional blister spot symptoms like I did three weeks ago.

EverCrisp

EverCrisp was sampled for the fourth week of the season. Looking at this week’s data and based on the starch index of 5.1, EverCrisp are ready to be harvested. This variety is known to be very firm at harvest and for high brix levels, which are currently testing at 15.8%. They eat much better this week. The predicted harvest date for EverCrisp is Oct. 23, or today, and about 15 days after the predicted harvest date for Red Delicious. Remember that this variety is so new that we don’t have a long track record of predicting its maturity.

This week, 90% of fruit tested had internal ethylene levels over 0.2 ppm. The pressure is still very firm at 21.2 pounds, well above the minimum of 18 pounds for best long-term CA storage. The average starch index has moved from 3.4 last week to 5.1 this week. A minimum of 3.0 for the starch index is recommended for harvesting for fresh sales of EverCrisp. Changing of background color from green to a lighter green or slight yellow appears to be a good indicator of a mature apple.

Fuji

Fuji was sampled for the fifth week of the season. Fuji were ready to begin harvest last week and based on this week’s data, some blocks are over mature. The predicted harvest date for Fuji is Oct. 23, or today, but they were mature well ahead of this date. This week, 40% of the fruit tested had internal ethylene levels over 0.2 ppm and the pressure is still firm at 20.9 pounds. The color has improved compared to three weeks ago. The average starch index has jumped from 4.7 last week to 5.7 this week. Fuji maturity was well ahead of Red Delicious.

Cameo

Cameo was sampled for the fourth week of the season and are ready to begin harvest. I don’t have Cameo on the predicted harvest dates list in the table that follows, but it matures between Rome and Fuji, or around Oct. 20. This week, 70% of fruit tested had internal ethylene levels over 0.2 ppm and the pressure is 18.8 pounds. The average starch index has moved from 3.0 last week to 4.2 this week.

Braeburn

Braeburn was sampled for the third week of the season and are still not ready to begin harvest. The predicted harvest date for Braeburn is Oct. 28. Two weeks ago, I shared that Braeburn would mature before this date, but looking at this week’s data, that date may be close to being accurate. This week, 20% of fruit tested had internal ethylene levels over 0.2 ppm and the pressure is still rock hard at 24.2 pounds. The average starch index is 2.1 this week.

Winesap

Winesap was sampled for the second week of the season and are not ready to begin harvest. The predicted harvest date for Winesap is Oct. 30. Last week, I shared that Winesap would mature before this date, but looking at this week’s data, that date may be close to being accurate. This week, 80% of fruit tested had internal ethylene levels over 0.2 ppm and the pressure is firm at 20.3 pounds. The average starch index is 2.1 this week.

Enterprise

Enterprise was sampled for the second week of the season and are close to being ready for harvest but need more time to mature. I do not have a predicted harvest date for Enterprise on the table below, but it is very close to the predicted harvest date for Winesap, which is Oct. 30. None of fruit tested this week had internal ethylene levels over 0.2 ppm and the pressure firm at 23.0 pounds. The average starch index is 2.7 this week.

Predicted peak fresh market apple harvest dates for east Michigan

Each year we publish predicted harvest dates for many locations across the state. These predicted harvest dates are based on a long-established formula using the bloom date and temperatures for 30 days post-bloom.

The following table has predicted apple harvest dates for east Michigan. It has been expanded to include more apple varieties and lists only one date for the entire east Michigan region, which is hard to do! You can adjust these predicted harvest dates based on your actual bloom dates or on the typical harvest dates at your farm.

These dates are an estimate and will be affected by the apple strain, rootstock, crop load, fertility, soil type, and other factors including weather this season. Keep a close eye on these weekly Apple Harvest Updates for possible revisions of these dates.

*Firmness is measured with a mechanical 11-millimeter wide probe inserted into the pared flesh of a fruit to a distance of 8 millimeters. Starch index is measured on equatorial cross section of an apple stained with iodine solution and rated using the Cornell University starch-iodine index chart for apples on a 1-8 scale (Predicting Harvest Date Window for Apples by Blanpied and Silsbey, Cornell Extension Bulletin 221.)