Madeline Wimmer- Extension educator (wimm0035@umn.edu)
This year’s unique weather patterns have had a notable impact on Minnesota’s fruit-growing season. The growing season started off with frequent rain events that created a number of challenges for fruit growers related to pest management and overall plant stress, and was followed by a warm, dry late-summer, which has now led to a dry fall, with many regions of Minnesota experiencing moderate (D1, refer to drought map images above) to severe drought conditions (D2).
A recent UMN WeatherTalk article explained how the average fall (September 1 - November 30) precipitation in Minnesota typically ranges from 6-8 inches. While some regions have received between 1-4 inches of rain, many other areas have had about 1 inch or less as of late October. Since then, more rain events have happened in many regions, but the article mentions that it still may not be enough to replenish, or recharge, the water within the soil profile going into winter 2024/2025, which could potentially be alleviated if we receive sufficient rain events in Spring 2025. As the growing season begins for fruit crops next year, stay tuned for an update about drought conditions and information related to production based on the current conditions.
At the end of October, UMN Extension received a report from a blueberry grower in Outagamie County in Wisconsin (Zone 5a) who observed abnormal bud development on their blueberry shrubs. Amaya Atucha, who studies cold hardiness and dormancy in fruit crops at the University of Wisconsin-Madison, has mentioned that this can happen during falls with warm temperatures. Because the blueberries in this scenario still had foliage and had not gone fully dormant, the buds were in a state of paradormancy, which is more like a temporary pause in growth and a state in which buds are still sensitive to external changes.
Images: A number of blueberry floral and vegetative buds showing signs of development during a time of year when buds are typically acclimating into dormancy. As colder temperatures continue and the day length shortens, bud development will slow down and stop altogether. Photos contributed by a blueberry grower in Outagamie Co., Wisconsin (Zone 5a).
Growers who are seeing similar abnormal bud development may be wondering what they can do to slow it down, but there isn’t a lot that can be done, practically speaking. As colder days and nights compliment our shortening daylength, buds will eventually transition from paradormancy to endodormancy—a deeper state of dormancy—and will remain that way until they finish their chilling requirements. It’s worth noting that a few Minnesota growers who grow in similar USDA hardiness zones were reached out to and reported little if any abnormal bud development at their blueberry farm.
Fall drought conditions update:
Images: Minnesota maps showing drought intensity for the state on October 24th and November 7th, 2024. Viewers may note that while recent rainfalls in some Minnesota regions have relieved parts of the metro and the southeast corner, many regions are still experiencing drought levels ranging from abnormally dry to severe drought levels.
A recent UMN WeatherTalk article explained how the average fall (September 1 - November 30) precipitation in Minnesota typically ranges from 6-8 inches. While some regions have received between 1-4 inches of rain, many other areas have had about 1 inch or less as of late October. Since then, more rain events have happened in many regions, but the article mentions that it still may not be enough to replenish, or recharge, the water within the soil profile going into winter 2024/2025, which could potentially be alleviated if we receive sufficient rain events in Spring 2025. As the growing season begins for fruit crops next year, stay tuned for an update about drought conditions and information related to production based on the current conditions.
Abnormal blueberry bud development observed:
While there have been frost events so far this fall and a number of colder days, there have also been a number of days that reach temperatures in the high 70s or even low 80s. The UMN WeatherTalk newsletter has also mentioned this recently, stating that some regions were experiencing temperatures that were on average 8F warmer than average, and this is historically Minnesota’s 6th warmest October.At the end of October, UMN Extension received a report from a blueberry grower in Outagamie County in Wisconsin (Zone 5a) who observed abnormal bud development on their blueberry shrubs. Amaya Atucha, who studies cold hardiness and dormancy in fruit crops at the University of Wisconsin-Madison, has mentioned that this can happen during falls with warm temperatures. Because the blueberries in this scenario still had foliage and had not gone fully dormant, the buds were in a state of paradormancy, which is more like a temporary pause in growth and a state in which buds are still sensitive to external changes.
Images: A number of blueberry floral and vegetative buds showing signs of development during a time of year when buds are typically acclimating into dormancy. As colder temperatures continue and the day length shortens, bud development will slow down and stop altogether. Photos contributed by a blueberry grower in Outagamie Co., Wisconsin (Zone 5a).
Growers who are seeing similar abnormal bud development may be wondering what they can do to slow it down, but there isn’t a lot that can be done, practically speaking. As colder days and nights compliment our shortening daylength, buds will eventually transition from paradormancy to endodormancy—a deeper state of dormancy—and will remain that way until they finish their chilling requirements. It’s worth noting that a few Minnesota growers who grow in similar USDA hardiness zones were reached out to and reported little if any abnormal bud development at their blueberry farm.
If you are a fruit grower noticing similar development, feel free to reach out by email to Madeline Wimmer at wimm0035@umn.edu to share your observations.
Additional resources:
Additional resources:
- Chilling requirements for plants - University of Illinois Extension
- Blueberry growth stages - Michigan State University Extension
- Minnesota WeatherTalk - UMN Extension weather newsletter
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