MSU Extension Apples

General apple harvest comments

Monday was the fourth week of apple harvest to collect apple samples from a number of orchards in east Michigan to test their maturity. Honeycrisp, Early Fuji, Jonathan, Jonagold, Empire, CrimsonCrisp and Cortland were sampled again this week, and new varieties added this week are Golden Delicious, Red Delicious and Idared to get an early read on their maturity. Samples were then delivered on Monday afternoon to the Department of Horticulture Post Harvest Lab at Michigan State University and analyzed yesterday. Data was forwarded on to me last night, analyzed and the result of this effort is todays fourth apple harvest update for east Michigan.

Based on this week’s data, Early Fuji and Jonagold are ready for harvest. Honeycrisp have matured quickly in the past week, with many blocks ready for their third and final picking. Some blocks of Jonathan are also ready to begin harvest, other Jonathan blocks need a few more days to mature. Empire at close to being mature at some farms, most however are about a week away from being ready to begin harvest.

Apples have continued to size well this season, with growers reporting that most varieties are picking out long. Fruit color has continued to improve with cooler weather. Golden Delicious finish is very good this season. The average brix or sugar levels have taken another nice jump in the past week.

Demand at farm markets, farmers markets and pick-your-own sales has been outstanding so far this fall, with many growers reporting record sales for this time of the season. Sweet cider continues to taste better as more varieties are available to be added to the blend. Demand for sweet cider has also been very strong this fall.

The normal and predicated apple harvest dates for east Michigan continue to be a part of today’s apple harvest report. The predicted harvest dates are based on temperatures from spring to 30 days after bloom and do not take into account summer temperatures, which can push development earlier or later than predicted. The predicted dates are a few days behind normal or most years, but as we are continuing with harvest many apple varieties are ahead of normal by a few days. See the Michigan State University Extension article, “Predicted 2020 apple harvest dates” by Phil Schwallier, for more details on how these dates are calculated.

On the apple crop pest front, brown marmorated stink bug trap catch numbers collected on Monday, Sept. 21, continue to be low for this time of the season. Bitter pit is continuing to be seen this week in Honeycrisp and Jonagold.

Individual variety results

Honeycrisp was sampled for the fourth week of the season. This week I only sampled a few ReTain treated blocks, so the data in the table below will be hard to compare this week to the previous three weeks. Most Honeycrisp blocks have been picked twice, and growers are going back now for the third and final picking.

The predicted harvest date for Honeycrisp was Sept. 19 and based on last weeks’ data, it was ready to harvest several days ahead of this date. Based on this weeks’ ReTain treated data, the product seemed to delay maturity by at least a week, if not longer. Even ReTain treated Honeycrisp blocks are now ready for a light first picking.

Early Fuji was sampled for the third week of the season. Based on this weeks’ data, Early Fuji are ready to begin harvest. The predicted harvest date for Early Fuji was Sept. 16. The percentage of fruit with internal ethylene levels over 0.2 parts per million (ppm) is 95%. Fruit color has improved slightly to 71% this week. The average starch index is 5.5 this week, up from 3.8 last week and the brix improved to 15.6%.

Jonathan was sampled for the second week of the season. Based on this week’s data, Jonathan are very close to being mature. In fact, in the few days since this week’s samples were collected on Monday, Sept. 21, and today, Jonathan may be ready to begin harvest today or in the next few days. The predicted harvest date for Jonathan is Sept. 26, so it is maturing very close to this date.

The percentage of fruit with internal ethylene levels over 0.2 ppm is up slightly to 57 %. Fruit color is excellent at 93%. The average starch index is 3.5, up from 2.8 last week, with the brix or sugar level up to 14.9%.

Jonagold was sampled for the second week of the season. Based on this weeks’ data, Jonagold are ready to harvest. In last week’s report, I stated that Jonagold were only a few days from the beginning ready to begin harvest. The predicted harvest date for Jonagold is Sept. 26, so they were ready to harvest a few days ahead of the predicted harvest date. The percentage of fruit with internal ethylene levels over 0.2 ppm is up from 33% last week to 58% this week. Fruit color is still generally fair to good at 58%. The average starch index is unchanged at 4.7 this week.

Empire was sampled for the second week of the season. Based on this weeks’ data, Empire are still not ready to begin harvest. The predicted harvest date for Empire is today, Sept. 23, but they still need more time to mature. The percentage of fruit with internal ethylene levels over 0.2 ppm is still low at 5%. Fruit color is good at 73%. The average starch index is up from 2.3 last week to 2.9 this week.

CrimsonCrisp was sampled for the second week of the season. Based on this weeks’ data, CrimsonCrisp are ready to begin harvest. I do not have a predicted harvest date established for CrimsonCrisp yet, but I believe it matures just before the harvest window dates for Jonathan and Jonagold, or around Sept. 21. The percentage of fruit with internal ethylene levels over 0.2 ppm is still at 100%. Fruit color is excellent at 93%. The average starch index is up from 4.4 last week to 6.2 this week.

Cortland was sampled for the second week of the season. Based on this weeks’ data, Cortland are still not ready to begin harvest. The predicted harvest date for Cortland is Sept. 28. I do not believe they will be mature by this date. The percentage of fruit with internal ethylene levels over 0.2 ppm is 60%. Fruit color is good at 84%. The average starch index is up from 1.1 last week to 1.7 this week.

Golden Delicious was sampled for the first week of the season to get an early read on its maturity. All of the samples tested were the Smoothee strain. Based on one weeks’ worth of data, Golden Delicious are not ready to begin harvest. The predicted harvest date for Golden Delicious is Oct. 1. The percentage of fruit with internal ethylene levels over 0.2 ppm is 10%. Fruit color or blush is good at 25%. The average starch index is 1.9 this week. The finish on Goldens is excellent this season, maybe the best I have ever seen.

Red Delicious was sampled for the first week of the season to get an early read on its maturity. Scarlet Spur and Red Chief strains were sampled this week. Based on one weeks’ worth of data, Red Delicious are not ready to begin harvest. The predicted harvest date for Red Delicious is Oct. 3. The percentage of fruit with internal ethylene levels over 0.2 ppm is 7%. Fruit color is good at 89%. The average starch index is 2.0 this week. Red Delicious are eating very green.

Idared was sampled for the first week of the season to get an early read on its maturity. Based on one weeks’ worth of data, Idared are not ready to begin harvest. The predicted harvest date for Idared is Oct. 9. The percentage of fruit with internal ethylene levels over 0.2 ppm is 10%. Fruit color is good at this time at 77%. The average starch index is 1.1 this week.

Note: 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.)

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. It 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 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.