Southwest Michigan apple maturity report – Oct. 17, 2018

William Shane<shane@msu.edu> - October 17, 2018

Harvest of Fuji, Rome and Braeburn is the focus in southwest Michigan.

Kumeu Crimson Braeburn is one of the last apple varieties of the season. Photo by Bill Shane, MSU Extension.

General apple harvest comments

This is the last apple maturity report for southwest Michigan for the 2018 season. Red Delicious are nearly all harvested in central southwest Michigan. A few Golden Delicious blocks are finishing up.

Brown marmorated stink bug activity has declined over the past week with the return of cool weather. Damage to apple fruit late in the season may be overlooked, but show up later in storage. Scout for insect damage, especially on orchard borders. Stink bug damage could still continue on sunny, still days.

Apple maturity in southwest Michigan for apples harvested Oct. 8
Variety	Firmness lbs. (range)	Starch (range)	Brix %
Fuji	16.9 (15.5-18.7)	5.3 (4.6-6.0)	14.3
Rome	21.6 (20.8-22.4)	4.5 (4.2-5.4)	11.2
Braeburn	19.9 (18.1-21.6)	4.4 (3.4-5.6)	11.9
Evercrisp	21.1 (20.9-21.2)	4.2 (3.2-5.0)	16.9

Individual variety results

Fuji were tested for the fourth week. Starch conversion is averaging 5.3, slightly higher than last week, with 3.0 given as the minimum for mature for this variety. Fruit firmness averaged 16.9 pounds this week, with the general guideline of a minimum of 17 pounds for best midterm controlled atmosphere (CA) storage. Background coloration is improving and internal maturity is relatively advanced and appears to be ahead of the predicted peak harvest date of Oct. 22 for central Berrien County. Brix for this week is 14.3 percent.

Fuji maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 24	19.5 (17.5-20.4)	3.4 (2.8-3.8)	12.0
Oct. 1	19.0 (17.1-20.3)	3.6 (3.4-4.0)	12.5
Oct. 8	18.4 (17.4-20.3)	5.1 (4.2-7.0)	13.5
Oct. 15	16.9 (15.5-18.7)	5.3 (4.6-6.0)	14.3

Rome was tested for the third week this season. Starch conversion is averaging 4.5 this week, with 3.0 as the minimum for mature for this variety. Brix for this week is 11.2. Fruit firmness averaged 21.6, similar to last week, with the general guideline of a minimum of 18 pounds for best long-term CA storage. Background coloration is still relatively green. The predicted peak harvest date is Oct. 8 for central Berrien County, which seemed to be on target.

Rome maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Oct. 1	23.7 (22.9-24.4)	3.0 (2.8-3.2)	10.7
Oct. 8	21.8 (21.4-22.3)	3.2 (3.0-3.6)	10.9
Oct. 15	21.6 (20.8-22.4)	4.5 (4.2-5.4)	11.2

Braeburn were tested for the third week. Starch conversion is averaging 4.4 compared to 3.8 for last week, with 3.0 as the recommended minimum value to be considered mature for this variety. Brix for this week is 11.9, same as last week. Fruit firmness averaged 19.9 pounds, with the general guideline of a minimum of 18 pounds for best long-term CA storage. Background coloration is still relatively green, with a predicted peak harvest date of Oct. 22 for central Berrien County. Internal maturity has been reached, but continued high fruit firmness will allow harvest to be delayed waiting for higher sugar content.

Braeburn maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Oct. 1	22.1 (20.2-23.5)	2.7 (1.0-4.2)	11.0
Oct. 8	21.5 (20.0-23.0)	3.8 (2.8-4.6)	11.0
Oct. 15	19.9 (18.1-21.6)	4.4 (3.4-5.6)	11.9

Evercrisp (MAIA1) were tested for the second week. Starch conversion is averaging 4.1 this week, about the same as last week, with 3.0 as the minimum for mature for this variety. Brix for this week is 16.9. Fruit firmness averaged 21.1 pounds compared to 23.4 pounds last week, with the general guideline of a minimum of 18 pounds for best long-term CA storage. A few apples are showing water core.

Evercrisp appears to be midway in vigor between Fuji and Honeycrisp, its two parents. It is a tip bearing tree that is a consistent cropper. Like Fuji, the fruit quality and red skin are greatly improved by proper thinning. On sandy sites, low vigor rootstock like Bud 9 may cause Evercrisp trees to runt out.

Evercrisp maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Oct. 8	23.4 (23.1-23.7)	4.1 (3.0-5.0)	15.8
Oct. 15	21.1 (20.9-21.2)	4.2 (3.2-5.0)	16.9

Normal and predicted 2018 peak harvest dates for apple varieties in southwest Michigan based on weather data at the Southwest Michigan Research and Extension Center, Benton Harbor, MI.
Variety	Normal date	2018 Predicted peak harvest date
Paula Red	Aug. 22	Aug. 20
Zestar	Aug. 22	Aug. 20
Gingergold	Aug. 20	Aug 18
McIntosh	Sept. 10	Sept 8
Gala	Sept. 8	Sept 6.
Early Fuji	Sept. 3	Sept. 1
Honeycrisp	Sept. 13	Sept. 13
Empire	Sept. 19	Sept. 23
Jonathan	Sept. 22	Sept. 24
Jonagold	Sept. 22	Sept. 24
Golden Delicious	Sept. 25	Sept. 27
Red Delicious	Sept. 28	Oct. 1
Ida Red	Oct. 5	Oct. 8
Rome	Oct. 5	Oct. 8
Fuji	Oct. 20	Oct. 22
Braeburn	Oct. 20	Oct. 22
Goldrush	Oct. 26	Oct. 28

Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety.
Variety	Firmness (pounds)*			Starch Index*
Variety	Short CA	Mid-CA	Long CA	Mature	Over mature
McIntosh	14	15	16	5	7
Gala	16	17	18	3	6
Honeycrisp	15	16	17	3.5	7
Empire	14	15	16	3.5	6
Early Fuji	16	17	18	3	7
Jonagold	15	16	17	3.5	5.5
Jonathan	14	15	16	3.5	5.5
Golden Delicious	15	16	17	3	6.5
Red Delicious	16	17	18	2.5	6
Idared	14	15	16	3.5	6
Crispin / Mutsu	16	17	18	3	6
Fuji	16	17	18	3	7
Evercrisp	16	17	18	3	7
Rome	15	16	18	3	5.5
Braeburn	16	17	18	3	7

*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.

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