Northwest Michigan apple maturity report – Sept. 5, 2018

Cooler weather in the forecast should improve color on northwest Michigan apples.

September 5, 2018 - Author: , ,

General apple harvest comments

The end of August in the northwest region brought several days of rainy weather. Since Aug. 24, the Northwest Michigan Horticulture Research Center has received 5.46 inches of rain. This wet weather was welcomed following a dry summer, and these recent rains helped to size fruit. Size has been a concern with the dry conditions over the season, and trees without irrigation have shown signs of drought stress.

The forecast for the remainder of this week is calling for cooler evening temperatures that will help to improve fruit color. However, the extended forecast is predicting that temperatures will warm up across the state as a result of the peak of the Atlantic hurricane season. Fruit could ripen quickly if this warm weather returns.

Insect activity over the last few weeks, and particularly within last week’s rainy conditions, has slowed in the northwest. This week, we detected very few pests in our trap line. Apple maggot has not been detected at the station in the last three weeks; we have received reports of low apple maggot catches in the region. Codling moth numbers have steadily declined and no moths were found in our traps this week, indicating we are likely approaching the end of the second generation flight.

San Jose scale crawler activity has winded down and thus the optimal management window has passed. European red mite and twospotted spider mite activity has also slowed substantially. Although most insect activity has slowed, we have observed an uptick in brown marmorated stink bug activity in urban areas; catches of brown marmorated stink bugs continue to be low in orchards.

With the recent wet weather, diseases (e.g., sooty blotch and flyspeck) and fruit rots could be a concern.

This is the second 2018 apple maturity report for northwest Michigan and these data show that the following apple varieties are ripening. Harvest of early varieties (Gingergold, Premier Honeycrisp, SweeTango) is ongoing. Orchard conditions have been excessively wet, and even with the region’s sandy soils, wet soils have slowed orchard activities.

Apple maturity in northwest Michigan for apple collected on Sept. 4

Variety

Firmness lbs. (range)

Starch (range)

Brix

Color %

McIntosh

17.7 (17.6-17.8)

1.2 (1.1-1.3)

11.3

73.8

Gala

21.6 (21.3-21.9)

1.03 (1.0-1.05)

10.15

54

Honeycrisp

17.2 (16.7-17.7)

1.5 (1.2-1.6)

11.6

56.9

McIntosh firmness is decreasing, and starch indices and brix are on the rise since last week’s sample. Like many varieties this season, color has been a challenge with the warm weather. The normal harvest date for McIntosh is Sept. 22, but 2018 McIntosh harvest seems to be ahead of normal. Cooler weather should improve color, particularly in older strains of McIntosh.

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

Gala color has improved since last week with slight changes in firmness, starch indices and brix. In blocks where growers did not achieve good thinning, size is a challenge. However, overall Gala size looks to be close to normal for the region.

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

Honeycrisp firmness is also decreasing with increases in starches and brix. Bitterpit is becoming more apparent. However, there seems to be a relatively low level of bitter pit. We detected some internal browning in Honeycrisp samples from the station.

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

 

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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