General apple harvest comments

This is the second apple maturity report for northwest Michigan. Predicted harvest dates for apples in this region are nine to 12 days behind our normal harvest dates. Growers concur with these later harvest dates, and apple harvest seems to be on hold for many varieties.

This week, we tested Ginger Gold, SweeTango, Honeycrisp, Gala and McIntosh. Some growers have been spot picking Ginger Golds over the last week and harvest of the club variety SweeTango also began recently. While early pickings of Honeycrisp are starting to show up in markets, there is variability in ripeness of this variety across blocks, and our maturity testing suggests this variety is not ready to pick for fresh eating. As expected, Gala and McIntosh are also not yet ready for harvest, but McIntosh seem to be moving along slightly faster than Gala this week. Growers are waiting for fruit to ripen and are eager to start harvest, but there seems to be time before things are ready.

Color is improving on many varieties, but we could use some sunny weather to really color up the fruit. We have had cooler days (and nights), but we have had a lot of cloud cover in the past week, and more is predicted into the remainder of the week. Next week’s conditions look hot in the daytime and cooling down into only the 60s in the evening. Toward the latter part of next week, nighttime temperatures are predicted to drop into the 50s degrees Fahrenheit. Rain is expected to move back into the region starting next Sunday, Sept. 22. Again, growers are hoping for conditions to move color along.

Pest pressure continues to be relatively low.

Apple maturity in northwest Michigan for apples collected on Sept. 10, 2019
Variety	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Gingergold	6.5 (0 - 30)	17.7 (15.5 - 20)	1.6 (1 - 2)	11.2 (10.8 - 11.5)
SweeTango	89.3 (80 - 100)	16.95 (15 - 20)	3.2 (1.5 - 5)	13.1 (10.8 - 15.8)
Honeycrisp	53.9 (40 - 95)	18.6 (17 - 21)	1.4 (1 - 3)	11.5 (10 - 13)
Gala	64 (30-95%)	22.3 (19 - 23)	1 (1 - 1)	9.8 (8.5 - 11.5)
McIntosh	74.3 (15 - 100)	16.1 (13.5 - 19.5)	1.65 (1 - 3)	10.6 (9.7 - 11.4)

Individual variety results

Ginger Gold

We tested one sample of Ginger Gold this week and those fruits tested underripe. This sample was from a different block than those that were tested last week. These samples were still firm at 17.7 pounds pressure and starch index averages were only 1.6. Overall, Ginger Golds are tasting less starchy than last week.

Ginger Gold maturity sampling for the harvest season
Sample date	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 4	14.5	20.3	1	11.9
Sept. 10	6.5 (0 - 30)	17.7 (15.5 - 20)	1.6 (1 - 2)	11.2 (10.8 - 11.5)

SweeTango

We had a chance to sample SweeTango this week and there is a distinct candy-like flavor in some of the fruit. Color on this variety is good in most blocks, and there seems to be a little russeting on this variety. SweeTango harvest has started in northwest Michigan.

SweeTango maturity sampling for the harvest season
Sample date	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 10	89.3 (80 - 100)	16.95 (15 - 20)	3.2 (1.5 - 5)	13.1 (10.8 - 15.8)

Honeycrisp

Honeycrisp fruit are sizing well and starting to color. At theNorthwest Michigan Horticulture Research Center, we see quite a bit of variation in color from tree to tree. This situation is particularly distinctive in our NC 140 rootstock trial, which is notable as we look forward to new rootstocks for this variety. Fruit is still firm and brix is rising.

Honeycrisp maturity sampling for the harvest season
Sample date	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 4	50.5	19.6 (19.2-20.0)	1	10.8
Sept. 10	53.9 (40 - 95)	18.6 (17 - 21)	1.4 (1 - 3)	11.5 (10 - 13)

Gala

We tested three samples of Gala this week and fruit size is on the smaller end at this time. These fruit are still very firm and underripe, but coloring nicely. At the station, our thinning efforts in Gala seemed to be effective, but fruit are also on the small size. We have had issues with shoot blight in Gala this season, which may be impacting fruit growth in some trees/blocks.

Gala maturity sampling for the harvest season
Sample date	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 10	64 (30-95)	22.3 (19 - 23)	1 (1 - 1)	9.8 (8.5 - 11.5)

McIntosh

We tested two blocks of McIntosh this week and some blocks have nice color, which can be deceiving in terms of maturity. While this variety is moving along, most of these apples are not yet mature.

McIntosh maturity sampling for the harvest season
Sample date	Color % (range)	Firmness lbs. (range)	Starch (range)	Brix %
Sept. 10	74.3 (15 - 100)	16.1 (13.5 - 19.5)	1.65 (1 - 3)	10.6 (9.7 - 11.4)

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

*坚定与机械11-millime测量ter 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.)