Southwest Michigan apple maturity report

Southwest Michigan apple maturity report – Oct. 3, 2018

William Shane<shane@msu.edu> - October 03, 2018

Apple harvest is moving rapidly in southwest Michigan.

General apple harvest comments

Red Delicious is the targeted variety for many growers this week. A few Honeycrisp are still being harvested. Empire harvest is done except for a few for local sales, Goldens are nearly done and Jonagold are generally done with some being left in the orchard.

Sooty blotch and flyspeck disease is a problem in some orchards on fruit harvested next to woods. Some growers report problems with fruit rots associated with insect punctures. Bitter pit is showing up on some Honeycrisp fruit coming out of storage.

Brown marmorated stink bug activity was slowed by cool weather, but likely will resume with temperatures in the 80s.

Nighttime cool weather helps with red skin color development. According to Rich Marini, Penn State University, the effect of cool nights on red color enhancement depends on the apple variety. 'McIntosh' requires temperatures below 70 degrees, 'Fuji' requires temperatures in the low 60s and 'Redchief Delicious' requires temperatures in the low 50s, but one day at 90 degrees will negate the effects of several cool nights.

Apple maturity in southwest Michigan for apples harvested Oct. 1
Variety	Firmness lbs. (range)	Starch (range)	Brix %
Golden	16.3 (15.6-16.9)	5.5 (3.4-7.0)	12.9
Red Delicious	16.6 (15.2-17.9)	4.0 (3.0-5.6)	10.8
IdaRed	17.3 (16.2-18.4)	2.7 (2.2-3.0)	11.4
Fuji	19.0 (17.1-20.3)	3.6 (3.4-4.0)	12.5
Rome	23.7 (22.9-24.4)	3.0 (2.8-3.2)	10.7
Braeburn	22.1 (20.2-23.5)	2.7 (1.0-4.2)	11.0

Individual variety results

Golden Delicious was sampled for the fourth week. Starch conversion jumped again this week, reading 5.5 compared to 4.2 last week, with 3 as the target for mature for this variety. The predicted peak harvest date is Sept. 27 for central Berrien County. Brix for this week is 12.9. Fruit firmness averaged 16.3 pounds this week, again about 1 pound less than last week with the general guideline of a minimum of 17 pounds for best long-term CA storage. Firmness of 16 pounds or above are considered sufficient for mid duration CA storage. Most area golden delicious have been harvested for processing uses.

Golden Delicious maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 11	18.2 (16-20)	1.5 (1.0-2.4)	11.1
Sept. 17	18.5 (17.0-19.4)	3.1 (2.2-5.0)	12.0
Sept. 24	17.4 (15.3-19.8)	4.2 (3.6-5.8)	11.7
Oct. 1	16.3 (15.6-16.9)	5.5 (3.4-7.0)	12.9

Red Delicious was tested for the third week. Starch conversion is averaging 4.0 this week, with 2.5 as the minimum for considering to be mature for this variety. The predicted peak harvest date is Oct. 1 for central Berrien County. Brix for this week is 10.8. Fruit firmness averaged 16.6 pounds this week, with the general guideline of 18 pounds for best long-term CA storage. Harvest of Red Delicious is going rapidly in the area.

Red Delicious maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 17	18.0 (17.0-20.0)	2.9 (2.4-3.6)	10.1
Sept. 24	17.3 (16.0-18.3)	3.5 (3.0-4.0)	10.3
Oct. 1	16.6 (15.2-17.9)	4.0 (3.0-5.6)	10.8

IdaRed were tested for the third week in southwest Michigan orchards. Starch conversion is averaging 2.7 this week compared to 2.1 for last week, with 3.5 as the minimum for mature for this variety. Brix for this week is 11.4, nearly the same as last week. Fruit firmness averaged 17.3 pounds, slightly less than last week. The general guideline is a minimum of 16 pounds for best long-term CA storage. A few IdaRed have been picked, with the current maturity with or slightly ahead of the predicted peak harvest date of Oct. 8 for central Berrien County.

IdaRed maturity sampling for the harvest season
Sample date	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 17	19.5 (19.0-20.0)	1.5 (1.0-2.0)	11.1
Sept. 24	17.9 (17.0-19.8)	2.1 (1.8-2.6)	10.9
Oct. 1	17.3 (16.2-18.4)	2.7 (2.2-3.0)	11.4

Fuji were tested for the second week. Starch conversion is averaging 3.6 this week, with 3.0 given as the minimum for mature for this variety. Brix for this week is 12.5. Fruit firmness averaged 19.0 pounds this week, with the general guideline of a minimum of 18 pounds for best long-term CA storage. Background coloration is still relatively green, but internal maturity is relatively advanced and appears to be ahead of the predicted peak harvest date of Oct. 22 for central Berrien County.

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

Rome were tested for the first time this week. Starch conversion is averaging 3.0 this week, with 3.0 as the minimum for mature for this variety. Brix for this week is 12.0. Fruit firmness averaged 23.7 pounds this 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.

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

Braeburn were tested for the first time this week. Starch conversion is averaging 2.7 this week, with 3.0 as the minimum for mature for this variety. Brix for this week is 11.0. Fruit firmness averaged 22.1 pounds this week, 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.

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

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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