MSU Extension Apples

General comments

The weather continues to be dry across the region, and we continued to have summer-like conditions until yesterday, Oct. 1, and into this morning. Yesterday started with the promise of rainfall, but true rain did not materialize, and conditions are extremely dry in the orchard. This dry weather has impacted the size of apples in orchard without irrigation, and some growers have used some Retain on smaller, later varieties to try and increase size of the fruit. In doing a quick look through Michigan State University Enviroweather, we have had very little rainfall at the Northwest Michigan Horticulture Research Center in the last two months. The weather station recorded 0.39 inches on Aug. 5-6. We had another 1/3-inch of rain on July 29 and another 0.5 inches of rain on July 23. Before that, we had just over an inch of rain around the Fourth of July. That is very little rainfall for the region for this time of the season.

In addition to the lack of rain, we have had warm conditions, which has compounded the droughty conditions in the orchard. Throughout most of September, we have had daily high temperatures in the 70s and 80s, and the nighttime temperatures have only dipped into the 50s but mostly 60s. This year seems like summer took on extra life. However, more fall-like weather is in the forecast, and daily highs will be in the 60s with nighttime lows into the mid-40s and low 50s. There were some reports of isolated frost this morning, Oct. 2, and my car thermometer read 37 degrees Fahrenheit when I left my house just north of Suttons Bay, Michigan.

Most growers are working to harvest most varieties. With the early season and many varieties maturing at a similar time, growers have been pressed to get the fruit off the trees. They have been working hard to move through harvest in an efficient manner. Many growers used Retain/Harvesta to help manage harvest this season in our region. Many growers estimate that they will be done with harvest in a week with the regular season varieties. We encourage growers to be testing (starch or eating fruit) to help determine when to harvest. In an early season like this one, growers cannot rely on their old typical harvest dates as the fruit is maturing quickly, and the fruit will be overmature before it is harvested. We recommend that growers do not rely solely on previous years’ harvest dates to determine when to harvest this season.

This is the sixth official week for apple testing in northwest Michigan (last week's report was reduced and contained in the FruitNet email). Reports are sent out on Wednesday every week, following the Michigan State University Extension fruit team apple maturity calls on Wednesday morning. Other relevant information on apple maturity can be found in the following links:

• Predicted apple harvest dates for northwest Michigan 2024 from Michigan State University (MSU).
• 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

Each week, we test apple varieties that are nearing maturity in northwest Michigan. We are reporting average values for several samples 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.

Honeycrisp

Most Honeycrisp trees have been harvested, and growers have reported some bitter pit in the orchard. There are a few hypotheses as to why bitter pit is higher in some blocks than others, and growers have seen differences between blocks, rootstocks and obviously crop load. However, the data seem a bit more confounding this year as some lighter crop loads have less bitter pit compared to heavier set blocks. There is some suggestion of the high amounts of rainfall earlier in the season that may have contributed to the higher levels of this disorder in some orchards.

Gala

Growers have been harvesting Gala for some time and have been limited to get this variety off by labor availability. Labor is not short, but with so many varieties and orchards maturing at a similar time, pickers have been working as quickly as they can to get the crop off. Color is beautiful in Gala in most blocks, and the quality is very good.

McIntosh

We have few McIntosh orchards in the region that we used, and most of these blocks have been harvested. Color was variable across blocks, likely as a result of tree size and the strains of this variety.

Fuji

We have very few later season Fuji blocks in northwest Michigan. We harvested our small block of a Fuji trial at the Northwest Michigan Horticulture Research Center this week. Fruit were light in color and on the small size despite that the block was irrigated. The notable conversation on the apple maturity call was that Fuji brix levels seem to be variable across the state. In our samples, we also had variable amounts of sugar, and most samples were testing in the 11% range.

Evercrisp

We only tested the Northwest Michigan Horticulture Research Center’s Evercrisp this week, and color is quite variable in our block. The fruit is still firm as we would expect with this variety. Starch was variable in our samples, but the average was 2.9. Brix was an average of 13.5. We will test more samples of Evercrisp next week. This variety is sometimes harder to ripen in our northern climate, but this year will be a good one for Evercrisp.

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

Be sure to check out our MSU Starch Index Chart!