Northwest Michigan apple maturity report – Sept. 19, 2018

Honeycrisp harvest is starting and this variety is maturing quickly.

September 19, 2018 - Author: , and

General apple harvest comments

Daytime temperatures are back up to summer-like heat in the upper 70s and 80s with cooler weather midweek and for the weekend in the forecast. The long range forecast for temperatures are predicted to be more representative of fall conditions—daytime temperatures in the 60s and 70s with evenings in the 50s. Rain is predicted for several days this week, and the chance for rain is between 10-100 percent with the greatest chance for rain on Thursday, Sept. 20. If rain comes, this wet weather would end an almost two-week stretch of mostly dry weather.

Honeycrisp harvest is starting and maturity is moving quickly. McIntosh is also maturing while Gala maturity has remained relatively consistent over the last three weeks. Overall, brix are lower this season. We anticipated that cooler evenings would provide significant color improvements, but conditions warmed up and color continues to be variable across blocks. Growers are using ReTain and waiting for color to improve. Honeycrisp maturity is moving quickly and there have been reports of drop of this variety in other regions of the state. Observations from downstate suggest Honeycrisp drop seems to be especially concerning in blocks with sandy soils.

Apple pests are winding down and most growers are ending insect pest programs. However, San Jose scale crawlers could be a concern and we found active crawlers on Honeycrisp while harvesting at the station this week. Warm conditions this season could be conducive for a third generation of San Jose scale.

Growers are also concerned with stink bugs, particularly the potential for damage from the invasive pest, brown marmorated stink bug. We have not received reports of brown marmorated stink bug damage thus far this season, and this pest has not been detected in traps in northwest Michigan orchards for several weeks. However, we have observed an uptick in brown marmorated stink bug activity in more urban areas. Our colleagues downstate have reported higher brown marmorated stink bug trap numbers within the last week.

Some growers are also concerned about sooty blotch and flyspeck, particularly in late varieties that are no longer protected with a fungicide. Although conditions have been mostly dry since early September, these diseases could get a foothold in late season varieties if we have a wet autumn. There is a sooty blotch and flyspeck model on Michigan State University’s Enviroweather.

This is the fourth 2018 apple maturity report for northwest Michigan, and these data show the following apple varieties are ripening. SweeTango harvest has slowed and growers are starting Honeycrisp harvest.

Apple maturity in northwest Michigan for apple collected on Sept. 18

Variety

Firmness lbs. (range)

Starch (range)

Brix

Color %

McIntosh

16.2 (15.2-17.1)

2.6 (1.9-4)

12.7

84.3

Gala

20.2 (20.1-20.3)

1.1 (1.1-1.1)

11.5

89

Honeycrisp

15.8 (14.9-17.1)

4.6 (4-5.2)

13.2

80.8

Individual apple variety results

McIntosh maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Aug. 27

19.4

1

10.4

71.5

Sept. 4

17.7 (17.6-17.8)

1.2 (1.1-1.3)

11.3

73.8

Sept. 11

16.8 (16.6-16.9)

1.9 (1.9-1.95)

11.8

79.3

Sept. 18

16.2 (15.2-17.1)

2.6 (1.9-4)

12.7

84.3

McIntosh apples are noticeably redder in color this week with improvements in brix. There is variability in firmness and starch indices from apple to apple and block to block; some apples remain firm and under-ripe while others are testing close to mature at this time. McIntosh harvest in northwest Michigan was predicted for Sept. 20 this season, and some McIntosh that will go into storage may be ready for harvesting at this time. Starchy flavor was detectable in most McIntosh samples this week.

Gala maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Aug. 27

22.65 (22.6-22.7)

1.0

9.85

39.2

Sept. 4

21.6 (21.3-21.9)

1.03 (1.0-1.05)

10.15

54

Sept. 11

20.2 (20.1-20.3)

1 (1.0-1.0)

10.95

78

Sept. 18

20.2 (20.1-20.3)

1.1 (1.1-1.1)

11.5

89

Gala color is continuing to improve as well as a slight increase in brix, but other maturity parameters show these apples are not ready for picking. These apples are still firm and unripe.

Honeycrisp maturity sampling for the harvest season

Date

Firmness lbs. (range)

Starch (range)

Brix

Color %

Aug. 27

19.8 (19.1-20.3)

1.1 (1.0-1.3)

10.7

45

Sept. 4

17.2 (16.7-17.7)

1.5 (1.2-1.6)

11.6

56.9

Sept. 11

16.6 (15.7-17.3)

3.2 (2.2-3.9)

12.1

72.1

Sept. 18

15.8 (14.9-17.1)

4.6 (4-5.2)

13.2

80.8

Honeycrisp maturity continues to move quickly with starch indices indicating these apples are ready for harvest. Honeycrisp harvest has started in the region, and the station began harvesting this variety on Monday, Sept. 17. Brix are not as high this season as we have observed in past seasons; color has also continued to be a challenge. We caution growers waiting for color to improve that these apples could become over-mature very quickly. As mentioned previously, we have received reports that drop has been a challenge in this variety downstate.

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.

Tags: apple harvest 2018, apple maturity reports, msu extension, northwest apple maturity report


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