MSU Extension Apples

This is the first apple maturity report for the 2021 harvest season for northwest Michigan. Reports are sent out every week (usually on Wednesdays) following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning.

• Considerations for the 2021 harvest season can be found in this article.
• More information on harvest management tools and timings can be found in this article.
• Guidelines from MSU to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety.
• Predicting apple maturity and starch chart from Cornell University
• Starch chart for Honeycrisp Apples developed by Washington State University.

How to read the maturity tables

For each variety evaluated, we provide data from our evaluations in a table. In each, a row is provided for each sample tested. This allows you to see how the varieties may be progressing in different regions or specific locations. An average is included for each variety. Maximum and minimum values are included for the highest and lowest individual fruits evaluated for each, to give a full spectrum of the maturity. Recommended values are included for each variety at the bottom of the table. These suggested values for firmness and starch index were also published in a standalone table format. Firmness ranges encompass long and short-term storage recommendations.

Updates for this week

Weather – According to the medium-term weather forecast, September is predicted to be warmer and wetter than normal. Daytime highs are predicted to be in the mid-70 degrees Fahrenheit and nighttime lows will dip into the mid-60s. This morning (Sept. 1) dropped into the high 50s, so some areas may see some cooler nights, which will be excellent for coloring up fruit. We did have some rainfall in the area over the weekend, and as per usual for 2021, there was a lot of variability in the amount of rainfall that fell. The Northwest Michigan Horticulture Research Center received 0.33 inches of rainfall on Aug. 28 and 0.9 inch of rain on Sunday, Aug. 29. There is a slight chance of more rain on Saturday, Sept. 4, and another slight chance on the following Monday, Sept. 6.

Ginger Gold – These early varieties are being harvested now. Maturity metrics (starch, firmness, soluble solids) are showing that this variety is starting to ripen, and sugar content is decent. Many fruits still have a green background color, and growers should look for a change in background color from green to green/yellow and development of varietal flavor. Ginger Gold size is excellent in the samples we tested at the Northwest Michigan Horticulture Research Center.

Gala – We tested Galas for the first time this week. Fruit is not yet ripe but remember that Gala can ripen more quickly in warm years as we have had in 2021. This variety can surprise us with early ripening with heat, and it can be mature before McIntosh in warm years. The Galas we tested still need time to ripen and to color up. The cooler nights should improve color.

Honeycrisp – We tested four samples of Honeycrisp this week, and fruit was quite variable in size between orchards. We tested some fruit that were on the small size, and there are many blocks in the region with a light crop and fruit size is large. This variety is still very green, and we are still a few weeks from harvest. We have typically harvested Honeycrisp at the Northwest Michigan Horticulture Research Center around Sept. 25. With the warm conditions this season, we anticipate harvest to be seven to 10 days earlier than this past harvest date. There is some bitter pit showing up in Honeycrisp, especially in orchards with a light crop, which is not surprising. There was very little bitter pit in the apple samples we tested this week.

Predicted harvest dates, according to the Maturity Model in MSU Enviroweather, are about 10 days earlier than normal for early varieties (Gala, Honeycrisp, McIntosh). At this time, we believe this will be fairly accurate.

Ginger Gold

Ginger Gold harvest is underway now across the northwest region, and this variety is at all the farmers’ markets and farm stands. Most of the fruit is starting to lose its green color and look more yellow. There was slight variability in the fruit samples we tested today. Some of the fruits were much more yellow to the eye, and these fruits ate well and did not have obvious starchiness. Other fruits were much greener and much starchier in flavor. Firmness in all the samples was good, and size was notable for almost all the apples we tested. Quality of Ginger Golds is excellent this year. We did not detect any bitter pit or any other blemishes on any of the fruit we tested.

McIntosh

We tested two samples of McIntosh this week. There are some signs of fruit beginning to mature; however, it will likely be a couple more weeks until McIntosh strains will begin harvest. Note that based on our bloom dates, the predicted harvest date for McIntosh in northwest Michigan is Sept. 14, which is only two weeks away. Keep an eye on this variety for early maturity. This variety has some nice red color, but the background color is still very green. Some of the fruit had a starch clearing of 2 or 3 but many were at 1. Brix levels in the two samples we tested were quite low at this time. We did eat a bite or two in the lab, and although the fruit was still starchy, the typical McIntosh flavor is detectable already this early. All samples were still firm. We did not observe a lot of apples on the ground in these McIntosh blocks, which can happen in some years.

Honeycrisp

Honeycrisp harvest is still about three to four weeks away until the fruit is mature enough to begin harvest. All fruit tested were very starchy and low in sugar content. Three of the four samples we tested were still very firm, but one sample from the Northwest Michigan Horticulture Research Center was noticeably softer. Again, size was variable in our samples, and we have observed variability in size in other orchards we have been testing for another project. Fruit is notably still green in color. We tested one block that has started to show red color, but most of the fruits were solidly green. Crop load is also quite variable in the region. We are working in blocks with excellent crops and other orchards are extremely light. In one block at the Northwest Michigan Horticulture Research Center, we have little fruit low in the trees with a good crop near the top of the trees. As mentioned above, we did not observe high amounts of bitter pit in our samples, but growers have commented on bitter pit in orchards where the overall crop is light.

As noted by Anna Wallis in her past reports, starch in this variety shows a considerably different pattern than other varieties. Refer to this starch chart (which uses a 1-6 scale and unique staining pattern) for maturity evaluation. The most recent Honeycrisp virtual meetup was on the topic of harvest and postharvest management of Honeycrisp with Randy Beaudry, Chris Watkins and others. You can find the recording on the MSU Kaltura Mediaspace Website.

Gala

We tested three samples of Gala this week, and some of the fruits were on the small side. One block at the Northwest Michigan Horticulture Research Center had noticeably small fruit, and according to the Duane Green thinning model, we had excellent results for our desired thinning goals. We have also had ample rainfall in addition to the irrigation we have in that block. We also noticed quite a bit of variability in color in the three samples. Some fruit is really started to color up while others were still quite green. The background color remains very green in all locations. Overall, the Gala crop is more consistent than the Honeycrisp crop, and the crop size looks excellent across the region. Many growers will likely use ReTain on Gala this year.

Apple maturity sampling parameters

• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested
• Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
• Starch: 1 = all starch, 8 = No starch; range is of all fruits tested. Using Cornell Starch Iodine Index Chart.
• Brix = % sugar measured with Atago PAL-1 Pocket Refractometer

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.