MSU Extension Apples

General comments

In the Grand Rapids, Michigan, area, apple maturity continues to run close to or slightly ahead of our 2020 predicted apple harvest dates for many varieties. Keep in mind these predicted dates are for peak harvest, so some fruits might be ready ahead or behind these dates as we move through maturity. Fruit color, finish, firmness and brix levels are all very good to excellent in 2020 for all varieties tested. In the general Grand Rapids area, we are past the peak of harvest and estimated to be about 80% of the way through the 2020 harvest season. Growers continue to report picking out at their estimate or even slightly above. Labor resources are good with no reports of shortages for harvest. Packing lines continue to have help wanted signs out.

On our Michigan State University apple maturity team call thins morning, all members reported that farm markets are having record-breaking crowds in 2020 with a strong uptick in the desire for U-pick apples and the farm adventure experience. While all of us in the business know how great it is to live the farm life, apparently others are coming to realize the same thing.

There are a few Red Delicious to be harvested, but that variety is nearly completed. Several growers are waiting on Fuji and other late varieties. If you find you have a break in your harvest schedule, this is a good time to work on fall orchard clean up (mowing, trellis repair, etc.). In blocks were harvest is complete, you could get started with post-harvest nutritional sprays or some fall herbicide needs.

Variety sampling results

Strains are noted where applicable. We try our best to collect samples from blocks untreated with harvest management products, but I do make note of samples that had ReTain applied if we know of it.

Somehow, we missed sampling in Red Delicious last week. Our predicted harvest date for Reds was Oct. 6 for peak harvest for the Grand Rapids area for untreated fruits. Our samples have ReTain applied and you can see the maturity results now show these fruits to be in the window for long-term controlled atmosphere (CA). If this fruit is still around next week, it will likely show movement to a lesser storage-ability.

Firmness is still very good at 16.5 pounds this week compared to 17.1 from two weeks ago. Starch readings are still very low at 2.8, which is not unusual for Red Delicious. Brix levels are outstanding in Reds at 14.8. Moldy core does not seem to be an issue in 2020 as it has been in the past few years—dry weather after bloom is likely the reason. We are seeing some water core in Red Delicious this year.

Our predicted harvest date for Ida Red was Oct. 11. This week’s sample again shows only a slight movement forward in maturity readings. Keep in mind this fruit was treated with ReTain. If you have Ida Reds, they are still in the window for long-tern CA storage, especially if treated with ReTain.

This is our second week to sample Romes and they are still on the immature side and have moved forward very little. Our predicted harvest date for the Grand Rapids area is Oct. 16. Color, firmness and brix are all nearing the range of early maturity, but they need some time to size up a bit. They are very hard to bite into and quite chalky and starchy yet.

Our Fuji sample is from a block of Aztec Fuji. Last week, it was surprising how far ahead they seemed to be. They continue to move forward slowly in their maturity. Color is outstanding on Fuji this year and if you feel it is what you want, it is really not too early to begin harvest of Fuji for long-term CA storage. Our predicted harvest date is Oct. 26, which is likely to be very much on the late side this year. It seems like we are always waiting for color in traditional Fuji strains, but that is not an issue this year. Picking them earlier rather than later might help avoid some potential water core issues this year. Looking at the numbers, Fuji is ready for long-term CA storage right now.

Evercrisp, like Fuji, seems to be ahead of the normal late October harvest timing, particularly when it comes to red color. The typical dull, green-brown background color is not as prominent in Evercrisp this year as well. This variety tends to have a high starch-iodine reaction, like Fuji, and it is good to look at all the other maturity parameters with Evercrisp. I bit into one this week and while they are juicy, they are still very hard and somewhat acidic that did not make for a very pleasant eating experience to me. In another week or two, they will be excellent for fresh eating. We are starting to see some watercore, so keep an eye on that in Evercrisp; all reports tell us it is very prone to watercore.

Granny Smith is making some slow movement forward in maturity and like some other late varieties, seems to be farther along in development than expected for mid-October. We continue to see water core in our samples, which is not typical for this late variety in the Grand Rapids area.

Many changes in apple physiology occur over time as fruit become more mature—starch is converted to sugar; seeds turn a darker color; acidity decreases; chlorophyll levels decrease; respiration increases; cell walls weaken, fruit begins to soften; and ethylene production increases. Our MSU Ridge Apple Quality Lab and the MSU campus Beaudry Lab measure these and many other factors to help you make harvest management decisions:

Apple maturity sampling parameters

• % fruits with internal ethylene over 0.2 ppm = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested
• Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
• Firmness in pounds pressure
• Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
• Brix = % sugar

We are graciously funded by the Michigan Tree Fruit Commission, Michigan Apple Committee, Michigan State Horticultural Society and Michigan State University Extension. Many thanks to all the growers and industry representatives that donate to our program.

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