MSU Extension Apples

General apple harvest comments

The maturity of apple varieties has quickly changed over the last week, with most varieties now testing as being mature. The cooler temperatures over the last week have pushed maturity along. Data from all five apple varieties tested this week indicate that all are mature to a few being over-mature. Even varieties that were on my slow to mature list this season, of late Idared and Crispin, saw rapid advances in maturity. Windy conditions late last week and the extreme winds, especially on Saturday afternoon, have resulted in a good amount of fruit drop.

Farms that have had adequate harvest labor this fall will be wrapping up harvest this week to early next week. For farms that have not had enough harvest labor this season, many will finish up with harvest late next week. This week, growers are harvesting several varieties, including Rome, EverCrisp, Autumn Gala, Braeburn and Winesap. More details on the maturity of most of these and other varieties follows.

This is the eighth and last Apple Harvest Report for east Michigan for the 2018 season. I plan conducting a follow-up survey in early November to gain your insight to improve this report for next year.

Brown marmorated stink bug (BMSB) activity has dramatically declined over the past week with the cooler weather, with almost all trap catches being zero. Damage to apple fruit late in the season may be overlooked at harvest but will show up later in storage. BMSB flight and damage could still continue on sunny, still days.

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

Individual variety results

Idared was sampled for the fifth week of the harvest season, and I could only find a few blocks this week to sample as many have been harvested. Idared were very slow to mature this season. In last week’s Apple Harvest Report, I stated that Idared were finally just ready to begin harvest. Based on this week’s data they were ready to harvest last week, and with the few blocks tested this week, they are over-mature for medium and long-term storage and need to be moved soon.

Maturity of Idared has moved quickly in the past week. The predicted harvest date for Idared was Oct. 4, and they were not ready for harvest by this date. The percent of fruit having greater than 0.2 ppm of internal ethylene has jumped from 63 percent last week to 100 percent this week. The fruit color this week averaged 97 percent, fruit firmness remained steady at 14.2 pounds and the starch index moved from 3.9 last week to 6.2 this week.

Crispin or Mutsu was sampled for the sixth week of the season. As was the case for Idared, many Crispin blocks were harvested in the last two weeks, thus I was limited in the number of blocks I could test this week. In last week’s report, I stated that a few blocks were ready to begin harvest the week before and that last week most Crispin blocks were ready to harvest. The predicted harvest date for Crispin was Oct. 6, so they matured just a few days beyond this date.

As was the case for Idared, Crispin maturity moved quickly in the past week and based on this week’s data, the remaining blocks are now over-mature. All of the fruit tested this week had internal ethylene levels greater than 0.2 ppm. The fruit color averaged 16 percent for the last three weeks and this week is about the same at 15 percent. The fruit firmness remained firm averaging 16.0 pounds and the average starch index jumped from 4.4 last week to an average of 7.4 this week. The fruit finish was excellent this season.

Rome was sampled for the third week of the season. Most Rome blocks have been harvested, so this is a limited sample size this week. I first sampled Romes on Oct. 8, and that data showed it was over-mature already. I sampled again last week to confirm its maturity, and indeed it was over-mature. Based on this week’s data, remaining unharvested Rome blocks are over-mature and are not suitable for short-, mid- or long-term storage.

While the predicted harvest date for Rome was Oct. 7, it now appears that it was mature well before this date. This week, the fruit color averaged 91 percent, fruit firmness is still good at 18.6 pounds and the starch index moved from 6.4 last week to 8.0 this week.

Braeburn was sampled for the third week of the season. Maturity moved quickly in the past week. Last week, Braeburn were not ready to begin harvest, but this week they are ready to harvest to even being over-mature for CA storage. The predicted harvest date for Braeburn was Oct. 21, and it now appears they were mature about on this date. This week, the fruit color averaged 71 percent, fruit firmness averaged 19.2 pounds and the starch index averaged 6.6.

Winesap was sampled for the second week of the season. Based on this week’s data, Winesap are ready to begin harvest. The predicted harvest date for Winesap is Oct. 26, and it appears from this week’s data that it may be ready to harvest a few days ahead of this date. This week, the fruit color averaged 91 percent, fruit firmness averaged 16.4 pounds and the starch index quickly moved from  an average of 1.7 last week to an average of 4.5 this week.

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.