MSU Extension

General apple harvest comments

Many blocks of Empire are ready for harvest, and growers in the south are now harvesting Golden Delicious. Jonathan and Jonagold harvest is wrapping up for many growers. Some growers have had a gap in harvest waiting for fruit to mature. Retain-treated Honeycrisp are also being harvested.

This is the fourth apple harvest report for the season; I have collected and analyzed apples for the last five weeks. This week, 11 apple varieties were sampled and tested for maturity, with Idared, CandyCrisp and Fuji being added to the mix. I will not continue sampling Jonathan and Jonagold next week, as they are mature.

Brix levels took another nice jump this past week, now at 12.3 percent when averaged over all varieties tested this week, even including the six varieties that are still immature. Cider tastes very good this week as the mix of varieties available has expanded in the past week. Fruit size is generally fair to good this season, but due to the drought, not as large as most years. Harvest labor remains in short supply.

As a reminder, with the early and long bloom in apples this spring and the continued heat of this summer, apple growers are finding that apple maturity is much less uniform than in most years. With cooler weather predicted over the next week, apples will ripen quicker. Harvest may slow down over the next week if the predicted rain comes to be a reality.

The table with the normal and 2016 peak harvest dates for apple varieties in east Michigan continues to be included at the end of this report. I encourage apple growers to spend some time in the orchard to evaluate the maturity of your apple varieties to make sure you are on top of apple harvest.

Black rot on fruit remains a problem at several farms, much worse in many blocks than the last few seasons. Sooty blotch and flyspeck are showing up more and more this week. Blister spot is starting to be seen in Crispin. Growers are encouraged to be on the lookout for brown marmorated stink bug insects and damaged fruit as apples are being harvested.

Individual variety results

Empire was sampled for the fourth week. While Empire has been maturing very slowly this season, many blocks are now ready to be harvested. They are eating much better than last week. The predicted harvest date for Empire was Sept. 14, however I think that for next season I will be adjusting the normal harvest date for Empire to be just ahead of Golden Delicious.

The percentage of fruit with internal ethylene levels greater than 0.2 parts per million (ppm) has stayed nearly the same over the last two weeks, now at 33 percent. Fruit color has also remained constant over the last two weeks at 78 percent, with fruit pressure still firm but dropping to 15.7 pounds. The average starch index moved from 2.5 last week to 3.6 this week, with a few blocks at 5.0. The brix has steadily improved as well, this week being at 12 percent.

Jonathan was sampled for the third week of the season. The predicted harvest date for Jonathon was Sept. 24. Most Jonathan blocks have been harvested or at least spot-picked. Some blocks of Jonathan are over-mature, with an average starch index of 6.7. Overall, Jonathan maturity is ahead of Empire this season; most Jonagold blocks are ahead of Jonathan this season.

The percentage of fruit with internal ethylene levels greater than 0.2 ppm rose sharply from 20 percent last week to 85 percent this week. The fruit color remains excellent at 95 percent and the fruit remain firm with a pressure of 16.4 pounds. The average starch index has risen from 3.0 last week to 4.9 this week. The brix was unchanged this week, at 13.6 percent.

Jonagold was sampled for the third week of apple harvest. The predicted harvest date for Jonagold was Sept. 24. All Jonagold blocks tested this week are mature to some being over-mature. Again, Jonagold are ahead of Jonathan and Empire. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 50 percent, with fruit color remaining the same at 59 percent this week. The pressure is still firm at 15.9 pounds and starch index averaging 6.2.

Cortland was sampled for the third week of the season, and is still immature. The predicted harvest date was Sept. 24. At this time they are well behind Empire maturity, more in the Red Delicious maturity window. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 20 percent, with fruit color good at 72 percent. The pressure is firm but dropping to 15.3 pounds and starch index at 1.2.

Golden Delicious was sampled for the third week of the season, with a predicted harvest date of Sept. 30. However, Golden Delicious have matured quickly in the last week, with some blocks and strains ready for harvest now. Many growers in the southern part of our region have been harvesting Golden Delicious for almost a week. Growers should take a closer look at them now to check for maturity.

The percentage of fruit with internal ethylene levels greater than 0.2 ppm remains low at 10 percent, with fruit color or blush remaining the same at 16 percent. The pressure is firm at 16.5 pounds and starch index jumping to an average of 4.3 this week from 2.2 last week. A few blocks have a starch index of 6.2.

Red Delicious was sampled for the second week of the season. All samples tested are the Redchief strain. The predicted harvest date for Red Delicious is Oct. 1, or five days from the date of this sampling. I think some blocks will be ready to harvest on this date, others will be four to five days later. Red Delicious still eats green and is not ready for harvest.

The percentage of fruit with internal ethylene levels greater than 0.2 ppm rose sharply from 7 percent last week to 63 percent this week. Color has improved to 93 percent. The pressure is firm at 16.4 pounds and starch index averaged 3.0, however a few blocks were at 4.5.

Northern Spy was sampled for the second week of apple harvest. They are still immature and eating very green. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 30 percent, with fruit color still poor at 16 percent. The pressure has dropped over 2 pounds, from 21.1 pounds last week to 18.5 pounds this week. The starch index is 1.6.

Crispin or Mutsu was sampled for the second week of the season. Crispin is still very immature and is not ready for harvest. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is unchanged at 0 percent or none, with fruit color at 14 percent. The pressure is firm at 18.4 pounds and starch index unchanged at 1.2. I did notice some fruit this week with blister spot symptoms.

Idared was sampled for the first week of the season, mainly to get an early read on its maturity. Idared is still very immature and is not ready for harvest. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 50 percent, with fruit color at 68 percent. The pressure is 16.5 pounds and starch index at 1.8.

CandyCrisp was sampled for the first time this season, mainly to get an early read on its maturity. CandyCrisp is still very immature and is not ready for harvest. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 11 percent, with fruit color at 27 percent. The pressure is firm at 18.5 pounds and starch index at 1.3.

Fuji was sampled for the first time this season, mainly to get an early read on its maturity. Fuji is still immature and is not ready for harvest. The percentage of fruit with internal ethylene levels greater than 0.2 ppm is 0 percent or none, with fruit color at 68 percent. The pressure is firm at 18.6 pounds and starch index at 2.5.

Predicted apple harvest dates

Each year we publish predicted harvest dates for three varieties for many locations across the state. This year's “Predicted 2016 apple harvest dates” were published July 11. The table below has been expanded to include more apple varieties and it lists only one date for the entire region, which is hard to do. The information in the “Predicted 2016 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. 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 four 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, Westview Orchards in Romeo 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.