MSU Extension Apples

General apple harvest comments

Maturity of apple varieties seems to be falling into two distinct categories this harvest season: those that are maturing quickly and are ready to harvest ahead of schedule and those that are slowly and steadily moving toward maturity. The list of varieties that fall into the quick to mature or maturing early includes Golden Delicious, Northern Spy, Rome, Cameo, Fuji and EverCrisp. Most varieties are falling in this first list. The list of those slow and steady maturing varieties is the shorter, including Empire, Idared and Crispin.

The order of apple varieties ready to harvest is still a bit of a moving target this season. The order of varieties ready to harvest list is much different than in our typical season.

This week, growers are finishing harvest of Empire and Golden Delicious, and are working away at Red Delicious. Varieties that are ready now to or nearing harvest include Northern Spy, Crispin, Rome, Fuji and Cameo. I also am finding some EverCrisp blocks are close to being ready. Idared, Autumn Gala and Braeburn are not ready to harvest. More details on the maturity of each of these varieties follows.

This was the sixth week of our harvest season to collect apple samples on Monday from a number of orchards in east Michigan and have them analyzed Tuesday at the Michigan State University Department of Horticulture Post Harvest Lab. I then tabulated the data last night and early this morning to produce this report. The number of varieties tested this week expanded from nine last week to 12 this week. The list of varieties tested this week includes Empire, Golden Delicious, Red Delicious, Idared, Northern Spy, Crispin and Fuji, and this week I added Rome, Cameo, EverCrisp, Autumn Gala and Braeburn.

Growers involved in farm or direct marketing had another tough weekend of poor weather this past weekend, with rain and mist reported at many farms Saturday and Sunday. Sales at farms markets were down 40 to 60 percent compared to the same weekend in October for the last several years.

Brown marmorated stink bug (BMSB) have been flying in high numbers on several of the warm afternoons over the past week. Trap catches at MSU monitored trapping locations are still catching close to 60 BMSB at about a third of the orchards in east Michigan. More sooty blotch and flyspeck, woolly apple aphid and San Jose scale is being found at many farms. A number of blocks are also seeing lenticel rot and black rot symptoms.

Here is the link for the 2018 Predicted Harvest Dates article that was posted to our MSUE News website  in July. A list of predicated harvest dates for east Michigan is listed at the end of this article as well. I encourage apple growers to spend time in your orchard every few days to evaluate the maturity of your apple varieties.

Individual variety results

Empire was sampled for the fifth week of the season, with just a few blocks tested this week as many have been harvested. Empire has been on a short list of varieties this season that have been slowly and steadily moving toward maturity. Most Empire blocks were finally ready to begin harvest last week at this time. The predicted harvest date for Empire was Sept. 18, but they did not mature until early October.

The percentage of fruit with internal ethylene levels greater than 0.2 parts per million (ppm) has finally started to rise to 40 percent, indicating they are finally physiologically maturing. The fruit color is about the same averaging 79 percent, the pressure is still firm at 15.8 pounds and the average starch index is up from an average of 3.5 last week to 4.5 this week.

Golden Delicious was sampled for the fourth week of the season. As with the case for Empire, the number of Golden samples tested this week has dropped back as growers have harvested many blocks. Some Golden blocks were ready to begin harvest the week before last week, and last week the rest were ready for harvest. Based on this week’s limited data set, Golden’s are now over mature. The fruit color or blush was slow to develop in Golden’s this season, and thus some growers were slow to harvest them. They matured very close to the predicted harvest date of Sept. 23.

Red Delicious was sampled for the fourth week of the season with a good number of samples this week. Once again, this week I shifted the mixture of stains sampled as earlier maturing strains have been harvested. Two weeks ago, I stated that some early maturing Red Delicious strains and sites are ready to begin harvest, and that last week the middle of the road maturing strains were close to being ready for harvest. Based on this week’s data set, the more centered maturing strains of Red Delicious are ready to begin harvest.

The predicted harvest date for Red Delicious was Sept. 29, so they are maturing after this date. The fruit color remains very good at 95 percent, the average fruit firmness improved to 16.9 pounds and starch index moved from an average of 2.9 last week to an average of 3.4 this week. Just a few blocks that I have tasted this week are still eating green.

Idared was sampled for the third week of the harvest season. Based on this week’s data, Idared are not ready to begin harvest. The predicted harvest date for Idared was Oct. 4, so they were not ready for harvest by this date. Idared are on the list of slow to mature varieties this season. The fruit color has improved this week averaging 90 percent, fruit firmness averaged 16.1 pounds and the starch index has moved to 3.0 this week. They are still eating green at this time.

Northern Spy was sampled for the third week of the season. Based on this week’s data, many blocks are ready to begin harvest; some blocks were mature last week and could have been harvested. The predicted harvest date for Northern Spy was Oct. 3, so they matured close to or just a few days after this predicted date. The fruit color has washed out a bit due to heat over the last week and is now at 70 percent. The starch index averaged 3.8 last week and this week is averaging 4.2. Most blocks are eating fine at this time, while a few are still eating on the green side.

Crispin or Mutsu was sampled for the fourth week of the season. Based on this week’s data, many blocks of Crispin are ready to begin harvest while others are needing a few more days to mature. The predicted harvest date for Crispin was Oct. 6, so they matured close to or just a few days beyond this date. The fruit color is still averaging 16 percent, with the average starch index moving from 2.4 last week to 3.3 this week. However, the range of starch index is quite broad, ranging from an average of 1.3 to 5.4. Fruit finish is excellent so far this season; I have seen only a trace of blister spot showing up in Crispin. Some blocks are eating well at this time and others are still eating green at this time.

Rome was sampled for the first week of the season to get an early read on its maturity. Based on only one week of data, many Rome blocks are ready for harvest. The predicted harvest date for Rome was Oct. 7, and it appears from this week’s data that it was ready to harvest very close to that date. The fruit color is averaging 92 percent, fruit firmness averaging 17.7 pounds and the starch index averaged a surprising 5.6, with a range of 3.7 to 7.4.

Cameo was sampled for the first week of the season to get an early read on its maturity. Based on only one week of data, Cameo are very close to being ready to begin harvest, but most blocks need a few more days to mature. Cameo is a variety that can hang on the tree longer and still be in good shape. I didn’t have a predicted harvest date for Cameo on the chart that follows, but I would place it in the Fuji harvest window, or Oct. 18. Based on this first week of data, Cameo may be ready to harvest a few days ahead of this date. The fruit color is averaging 74 percent, fruit firmness averaging 17.6 pounds and the starch index averaged a surprising 3.7.

Fuji was sampled for the second week of the season. Based on this week’s data, most Fuji blocks are ready to begin a light first harvest and a few blocks are over mature and can be harvested in one picking. The predicted harvest date for Fuji is Oct. 18, and it appears from this week’s data that it was ready to harvest earlier. The fruit color is good for Fuji averaging 70 percent, fruit firmness averaging 18.8 pounds and the starch index averaging 4.8, with a very wide range of 2.7 to 7.3.

EverCrisp was sampled for the first week of the season to get an early read on its maturity. Based on only one week of data and a limited sample size, EverCrisp are close to being ready to begin harvest but most blocks need a few more days to mature. The predicted harvest date for EverCrisp is Oct. 17, and it appears from this week’s data it will be ready to harvest a few days earlier. The fruit color is good averaging 85 percent, fruit firmness averaging a very hard 21.6 pounds and the starch index averaged a surprising 3.8, with a wide range of 1.0 to 6.0. I would like to see another week’s worth of data to see where it is at next week.

Autumn Gala was sampled for the first week of the season to get an early read on its maturity. Based on only one week of data, Autumn Gala are not ready to begin harvest. The predicted harvest date for Autumn Gala is Oct. 14, and it appears from this week’s data it will not be ready by this date. The fruit color is averaging 68 percent, fruit firmness averaging a rock hard 23.7 pounds and the starch index averaged a surprising 1.9.

Braeburn was sampled for the first week of the season to get an early read on its maturity. Based on only one week of data, Braeburn are not ready to begin harvest. The predicted harvest date for Braeburn is Oct. 21, and it appears from this week’s data it will ready to harvest close to that date. The fruit color averaged 64 percent, fruit firmness averaging 20.8 pounds and the starch index averaged 1.7.

Predicted peak fresh market apple harvest dates for East Michigan

Each year we publish predicted harvest dates for three varieties for many locations across the state. This year's “Predicted 2018 apple harvest dates” were published July 10. These predicted harvest dates are based on a long-established formula using the bloom date and temperatures for 30 days post-bloom. The information in this article lists the bloom and harvest dates for Deerfield and Romeo, Michigan.

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. Due to the early start to our growing season and much above normal temperatures this summer, 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.

*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.)

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.