Grand Rapids area apple maturity report – September 17, 2014

Forward movement in apple maturity is quite slow.

General comments

In the Grand Rapids, Michigan area, the major variety being harvested right now is Gala with a few Honeycrisp being spot-harvested. Buyers are clamoring for Honeycrisp, but don’t be tempted to pick too early. Poor quality, immature Honeycrisp will not encourage return sales. Cooler weather of late is great for color development, but not so good for ethylene development, and forward movement in apple maturity is slower than expected.

Many growers are reporting a good labor supply present for harvest, but not an over-abundance. There seems to be a lower stress level in the labor arena coming into this harvest season than in 2013. Growers report picking out right on target or slightly over their targets.

Pest comments

If you were trapping codling moth two to three weeks ago over the five moths per trap accumulated threshold, you could have eggs hatching now that could cause stings. The very cool weather in the last week should have put an end to codling moth flight for 2014, but eggs could still be there from two to three weeks ago.

Some apple blocks have reported extremely high oriental fruit moth trap numbers in the past several weeks, particularly in the lakeshore counties. This third generation of oriental fruit moth can cause stings in apples for the next week or two. Insecticide covers need to be maintained in these high pressure blocks.

I’ve heard a few comments from growers about mice already being seen in orchards. This is the time to make an assessment of their presence to determine if you need to manage for them post-harvest. Watch for feeding evidence in apples on the ground or for their tunneling in the orchard row middles.

Summary of Grand Rapids apple maturity samples measured Sept. 16, 2014


Avg. ethylene (ppm)

% Fruits with ethylene over 0.2 ppm

Color % (range)

Firmness lbs. pressure (range)

Starch (range)

Brix (range)




79 (45-100)

16.8 (12.5-22.8)

3 (1-7)

11.1 (10.5-12)




98 (95-100)

16.5 (13.5-20.1)

6.5 (6-7)

11.2 (11-12)




55 (25-75)

11.5 (9.5-14)

6.4 (6-7)

9.9 (9-11)


Color and size continues to be excellent on Gala strains this year. Gala have moved forward in maturity, but at a slower pace than expected due to cool weather. Gala are in the window for long-term controlled atmosphere (CA) storage right now and will move to the mid-term CA storage category in seven to 10 days.

Starch clearing has increased from an average of 1.1 last week to 3 this week, with the range of starch readings being larger. Nearly all fruit measured (95 percent) had ethylene over the 0.2 ppm climacteric level. Pressure readings are lower from last week as expected with an average of 16.8 pounds pressure this week compared to 18.4 pounds last week. Brix levels have increased from 10.2 to 11.1 and Gala fruit taste much better.


McIntosh have moved very little in maturity in the past week. They are getting close for long-term CA storage in the general Grand Rapids, Michigan area and might prove to be a bit behind the predicted optimum long-term CA harvest date of Sept. 19. McIntosh will definitely be ready behind Gala this year, which is quite common after a cooler summer.

Ethylene continues to read low with no fruits being over 0.2 ppm. Pressure readings are indicating good firmness at an average of 16.5 pounds of pressure, similar to the previous two weeks of sampling. Color is excellent, particularly on the redder strains, but the background color is still green. Brix reading has only slightly improved – 11.1 this week compared to 10.8 last week. Pressure is very good at 16.5 pounds. Starch clearing is up considerably from 3.2 last week to 6.5 on average this week. Harvest for long-term storage of McIntosh can begin at any time color is right, and when you have time around Gala harvest.


Movement towards maturity in Honeycrisp continues at a slower than normal pace. There is some harvest of “shiners” happening for local on-farm markets, but only a small number of fruits are ready for fresh sales in the general Grand Rapids, Michigan region. Our predicted Grand Rapids, Michigan area harvest date is Sept. 22, which will be the when the window opens for widespread Honeycrisp harvest for fresh sales. At this time, only spot-picking is recommended.

Firmness readings are good at 11.5 pounds pressure on average, which is down considerably from last week’s 15.5 pounds. Starch readings have moved from 2.9 last week to 6.4 this week and brix are up slightly from 9.8 to 9.9 this week, which is quite low for Honeycrisp. All the maturity indices show Honeycrisp to be very near the major harvest window and a few more days on the tree will improve their quality immensely.

For the Hart/Shelby, Michigan area, growers can expect harvest dates for that area to be behind the Grand Rapids, Michigan area using this guide: along the lakeshore approximately six days behind Grand Rapids; areas inland about four days behind.

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

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