MSU Extension Apples

Predicted harvest dates are earlier than normal

Below are the harvest dates for select cultivars, predicted by the Michigan State University Enviroweather Apple Maturity Model, and the deviation from normal. You can find our full report about 2021 predicted apple harvest dates here.

After the warm, dry conditions earlier this spring, heat accumulation and phenology were nearly two weeks ahead of 30-year averages. The predicted harvest dates follow a similar trend. We hate to cut your summer vacation short, but this year may be an important year to prepare early!

These dates are based on model predictions, which were developed using data from previous seasons. However, they cannot account for all the factors contributing to maturity in the current season. There will also be some inherent variability between blocks due to specific environmental conditions and cultural treatments. It is likely these dates may be on the early side of actual harvest.

If these predictions are accurate, both Gala and McIntosh are expected to harvest in the first week of September. That means that this week is approximately 28 days or four weeks before harvest, corresponding with the earliest recommended timing for the stop-drop material ReTain applications. More information on harvest management tools and timings can be found in this article.

*Dates in this table were determined from average observations by industry members in the region.

Reminders and considerations for the 2021 season

How do 2021 harvest predictions compare? Early varieties are expected to be mature as much as 10 days earlier than averages this year. The model predicted McIntosh harvest for Sept. 4. This is 12 days ahead of averages and approximately 15 days ahead of last year! Paula Red, Gala and Honeycrisp are likely to be early as well. Later varieties seem to be less affected by the season, so their harvest dates are expected to be closer to the typical averages. The model predicted Red Delicious for Oct. 7. Other varieties in this window include Fuji, Rome and Braeburn.

Remember: These are model forecasts, which give us a rough estimate for harvest windows based on only a few set parameters. Make sure to use your own judgement, experience and evaluations to determine the optimal harvest timing of your crop.

Lighter crop expected across the region. In many areas this year, crop load appears to be somewhat lighter than average. This is especially true of varieties with biennial tendencies (Honeycrisp, Jonagold). Very light crops have also been reported across the Midwest and Northeast. This may lead to earlier maturity and larger fruit size in some varieties and greater chance of bitter pit, particularly in Honeycrisp.

Mixed maturity as a result of the prolonged bloom. The bloom period was long and cool this year. As a result, pollination was spread over a period of two weeks or more, leading to a similar spread of fruit development. We expect optimal maturity will also be spread over a range of dates. This may be especially problematic given the lighter crop expected. It will be tempting to harvest fruit in fewer picks, but it is important to make sure fruit is at appropriate maturity for long term storage. Immature or overripe fruit can both be more prone to disorders in long term storage. This will also have implications for stop drop materials (recommendations below).

Impact of dry conditions this spring. The unusually warm, dry conditions this spring (high evapotranspiration conditions) led to the worst soil moisture deficits our area has experienced in nearly 20 years. Fortunately, most of the drought has been alleviated by rainfall over the past month. Lasting effects of the drought could include smaller fruit size with the highest impact on trees with heavy crop. This may be countered by the warm temperatures after bloom, which were good for cell division. The drought may have contributed to poor calcium levels with possible shorter shelf life. Finally, the flower initiation during this period may have been negatively impacted and next years bloom may be somewhat compromised.

Stop drop materials. Three tools are available to help manage harvest in apples—NAA, ReTain and Harvista. Applications of these materials should be well timed for the best results. ReTain can begin as early as 28 or 30 days before harvest. You can read this short article to brush up on the basics of these materials. This year, target material applications slightly early from peak harvest to avoid early ripening apples dropping before the materials become effective. This will be especially important if temperatures are very warm during the month of August, as currently predicted.

Materials shortages. The supply chain is still catching up after the COVID disruption. As a result, many things are still on backorder or short supply, from lumber and metal to resin used for plastic products, to computer chips used in vehicles. If you need materials, make sure to put your orders in ASAP. It may already be difficult to purchase some things in time for harvest.

Need something you can’t get or have extra of something you’re interested in offering? Add it to our Orchard Classifieds & Exchanges List. Or send us an email and we’ll add it for you.

Food safety and Food Safety Modernization Act (FSMA) preparedness. “FSMA Produce Safety Inspections: What to expect, where to find resources” from Michigan Farm News is a great reminder of the expectations for this season and how to prepare. You can learn more about FSMA, food safety requirements and compliance from the MSU Agrifood Safety website. In addition, the Produce Safety Alliance (PSA) is a collaboration between Cornell University, the Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) that provides resources to help growers comply with the new FSMA requirements.

MSU Apple Maturity Program. We will again be providing weekly maturity reports to provide guidance about the maturity of specific varieties leading up to harvest dates and considerations for seasonal conditions. This season, we plan to include fruit samples from across the region to provide a picture of the geographic variation. Please look for these reports beginning at the end of August on the Michigan State University Extension Apples website.

Testing your own fruit. Optimal maturity in each block will be a little different, based on the variety, specific location and conditions. Maturity should be determined based on metrics including firmness, starch, soluble solids (sugars/Brix) and color. You can use these resources to help determine maturity date in your orchard:

• 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.