Northwest Michigan apple maturity report – Oct. 4, 2017

Honeycrisp harvest is almost complete in the northwest and growers are moving into later-season varieties.

General apple harvest comments

This is the sixth apple maturity report of the 2017 season. Growers made it through the hot weather during the last week of September and cooler conditions held for a week. This week started again with warmer conditions in the mid- to high 70s, but the remainder of the week is predicted to be in the mid-60s and back up into the low 70s over the weekend.

Rainfall was recorded throughout the region Sept. 28 and 29, but Michigan State University Enviroweather stations recorded varying amounts of rain in different locations. Some locations received over 0.5 inch of rain while other received less than 0.25 inch of rain. We also received rain last evening into this morning, Oct. 3-4, and the Northwest Michigan Horticulture Research Center’s Enviroweather station recorded just under 0.2 inch of rain so far. We have had ample amounts of rain across the region this season, and even with the drier conditions, trees are not showing much stress.

Most growers have finished Honeycrisp harvest this week. We picked the last of this variety at the Northwest Michigan Horticulture Research Center on Oct. 2 and fruit remain firm, but have less flavor than the apples picked on Sep. 23. McIntosh harvest is also wrapping up and we have observed more of this variety on the ground this week if it had not yet been harvested. Jonagold harvest is underway and growers are also picking Ida Red. We are still seeing water core in Jonagolds and in one of the four samples of Ida Red.

Again this week, we have seen reports of fairly severe sunscald in certain varieties. According to MSU’s Randy Beaudry, lighter skinned varieties tend to show sunburn more than darker varieties; previous work suggests anthocyanins play a role in preventing sunburn. There have also been reports of rots beginning in fruit that had sunburn as a result of the recent heat wave.

Labor has been sufficient, but accelerated maturity following the recent heat has been a challenge for growers and harvest crews due to an overlap in maturity of multiple blocks and varieties. Firmness is holding in all varieties across the state.

We are still seeing damage from brown marmorated stink bugs. We have refreshed and moved our traps near apple blocks in all five of the northwest counties. We will put out a second report after we check the traps this week. As mentioned in previous reports, we have not caught brown marmorated stink bugs in our traps; hence, the traps did not provide any indication that potential brown marmorated stink bug damage was on the horizon. The Ridge area also had this similar situation where they detected brown marmorated stink bug damage 30 days prior to catching the insects in their traps.

If you are detecting brown marmorated stink bug damage now and still have considerable time until you finish harvest, make an insecticide application to keep the damage to a minimum. The following products are related excellent for brown marmorated stink bug control: Lannate, Danitol, Actara, Lambda-Cy, Endigo and Leverage. Check for pre-harvest intervals as harvest is upon us. Send pictures or drop off apples to the Northwest Michigan Horticulture Research Center and we can help you identify if the damage is from brown marmorated stink bugs.

Apple maturity in Michigan for apples harvested Oct. 3

Variety

Firmness lbs. (range)

Starch (range)

Brix %

Jonagold

17.2 (16.7-17.7)

5.1 (4.7-5.6)

14.1

Ida Red

18.2 (17.0-18.9)

2.9 (2.5-3.4)

12.4

Mutsu/Crispin

21.5

2.2

13.8

Northern Spy

21.4

2.6

12.6

Pink Lady*

20.8

2

14.7

*First sample of the season and maturity results indicate these varieties are not mature at this time.

Individual variety results

Jonagold are eating well this season and harvest is underway. Since last week, firmness is down slightly, starch indices have continued to increase and brix percentages remain consistent. Although these apples are great for fresh eating, many Jonagold blocks will be harvested for processing. Water core has continued to show up in our samples. Color on Jonagolds is good.

Jonagold maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 12

19.8

1

12.2

Sept. 19

19.2 (18.9-19.5)

2.05 (1.9-2.2)

14.6

Sept. 26

18.7 (18.2-19.2)

3.6 (3.1-4.0)

14.5

Ida Red apples had noticeable color improvements this week in all four of the blocks we sampled. The apples are firm and brix percentages have improved, but starch indices indicate most blocks need more time to ripen. Water core was evident in one of the four blocks we sampled this week.

Ida Red maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 19

20.4

1.4

11.3

Sept. 26

20.3 (19.1-21.7)

1.8 (1.5-2.4)

12.4

We sampled one block of Mutsu/Crispin this week and while these apples are moving along, they are not yet ready for harvest at this time.

Mutsu/Crispin maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 26

21.7

1.9

12.2

Oct. 3

21.5

2.2

13.8

Similar to Mutsu/Crispin, Northern Spy are also not ripe, but these apples are moving in the right direction with increases in starch indices and brix percentages; color has also improved over the last week. We only had one sample of Mutsu/Crispin and Northern Spy, and maturity will likely vary across different blocks of apples.

Northern Spy maturity sampling for the harvest season

Sample date

Firmness lbs. (range)

Starch (range)

Brix %

Sept. 26

22.8

1.4

11.7

Oct. 3

21.4

2.6

12.6

 

Suggested firmness and starch index levels for long-term and shorter-term controlled atmosphere (CA) storage by variety.

Variety

Firmness (pounds)*

Starch Index*

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

Fuji

16

17

18

3

7

Rome

15

16

18

3

5.5

*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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