Jun 23, 2021Predicted 2021 Michigan apple harvest dates are available
The predicted harvest dates for all Michigan State University Enviroweather Stations are now available online.
This season, warm conditions early in the spring led to advanced bud development. Phenology has been approximately one to two weeks earlier than the 30-year average for the duration of the 2021 season. This is the opposite of the past two years, in which cool late winter climate delayed the development of spring buds.
Overall, the 2021 predicted harvest dates are earlier than normal. Most of the state is a few days early compared to the average and last year.
Challenging spring weather conditions seem to have become part of the new normal, and 2021 was no different. The season began with very warm conditions with heat accumulation and phenology approximately one to two weeks early all season. Several hard freezes occurred on April 2, 21 and 22, leading to very site-specific damage: some locations experienced total losses, while others were unimpacted, depending on development stage, variety and conditions. Most areas rushed into bloom due to hot weather over the weekend of May 2-3. Cool weather immediately afterward led to a prolonged bloom period, lasting over two weeks in most places. This has led to wide variation in fruitlet development and sizing, and will likely result in variation in ripening, requiring multiple harvests. Some apple set is from two-year-old and in some places from one-year-old wood that will produce a very mixed maturity at harvest along with the prolonged bloom period. Drought conditions could also play into maturity for 2021.
Predicted harvest dates for specific locations can be determined using the Apple Maturity Model on the Enviroweather website. These models for McIntosh, Jonathan and Red Delicious calculate predict harvest dates based on full bloom date and the temperatures in the 30 days after bloom. The model predicted dates for McIntosh appear to be much earlier and for Jonathan and Red Delicious appear to be a little later than expected. Given the weather extremes in the 30-day period used to make predictions, this is not unexpected. We have seen this before and it typically ends up being accurate. However, predicted harvest dates could be off a few days, especially due to the extended bloom and the cold weather at bloom time. Harvest dates may need to be adjusted as we get closer to harvest.
Crop load is highly dependent on specific location. In general, return bloom was extremely light to non-existent in some varieties (Honeycrisp and Jonagold) across the Midwest and Northeast this season. Gala crop load is moderate to heavy across the region, while many other varieties, including Fuji are very light. Blocks with light croploads will mature three or four days sooner then the predicted harvest dates while heavy crop loads will mature seven days later than the predicted dates.
Conditions during August and September will also affect harvest dates. If hot stressful weather occurs in August or September, apple maturity will be advanced, especially in early to mid-ripening cultivars.
Stop-drop materials. ReTain application should be applied 30 days before harvest. Harvista can be applied three to seven days before harvest. Use Table 3, 2021 predicted harvest dates for other varieties, to time ReTain applications and adjust for varieties and locations.
The tables below list the normal and predicted harvest dates for varieties across the state. Table 1 lists the predicted harvest dates for locations across the state of Michigan for 2021. Table 2 lists this year’s predictions compared to normal and last year. Table 3 lists the normal harvest dates for other varieties for the Grand Rapids area. This year’s predicted dates for other non-modeled varieties are a rough estimate based on the McIntosh, Jonathan and Red Delicious predicted dates and historical experience in the Grand Rapids area. Other areas of the state should adjust non-predicted varieties based on their own history.
Table 1. 2021 predicted peak harvest dates.
|Station||Full bloom date 2021||Predicted harvest date 2021||Observer|
|Table 2. 2021 predicted peak harvest dates compared to normal and last year.|
|Station||Days -/+ normal||Days -/+ last year|
|Table 3. Normal and 2021 peak harvest dates for varieties for the Grand Rapids area.|
|Variety||Normal date*||2021 predicted date|
*Dates in this table were determined from average observations by industry members in the region.
Photo at top: Michigan State University Extension