Article written by Madeline Wimmer, UMN Fruit Production Educator.
Welcome letter
Dear readers,
After a winter full of farmer conferences and pruning workshops, the 2026 growing season is rapidly approaching for many fruit crops throughout Minnesota. A big welcome to those who are joining this series for the first time! This is one of the main ways to follow fruit crop updates in real time through the University of Minnesota Fruit Production program.
New: Fruit crop observation form
Much information in the Fruit Update articles is instructional and rooted in evidence-based practices that will help you gain knowledge about your crops to establish annual routines for crop care; however, in order to gain a better understanding in regional patterns throughout the state, we rely on your input about what’s going on in the field in your region. That’s why, this year, we’re adding a link in our articles for you to share observations and questions you have about specific crops and varieties.
UMN Extension Fruit Crop Observation Report Form
What else is new?
Additionally, the formatting for updates will change slightly this year to reduce the length of each article. You can look forward to seeing more independent articles that complement the materials in our updates.
Trying to find previous articles to look back on information and trends? The University of Minnesota is going through a period of updating information for accessibility standards, which is why most of our past Fruit Update articles are off-line. These will be reposted as they are worked on, but please reach out if there is anything you are looking for!
Management information provided in this series:
This series aims to provide information to commercial fruit growers who are following conventional or organic approaches to fruit production. For pest management, the Midwest Fruit Pest Management Guide is heavily referenced, which primarily focuses on conventional management practices. If you’re new to pest management specifically for apples, you might be interested in joining the Integrated Pest Management (IPM) Institute’s Apple Talk series, which has already started and runs throughout the growing season as a webinar-based series.
For more information on organic management practices, there are several guides that can be found online for several fruit crops:
Apples:
Grapes:
Organic Grapes (University of Wisconsin)
Berries:
General Resources for Organic Production:
Sincerely,
Madeline Kay Wimmer
UMN Extension Fruit Production Educator
Fruit updates: Apples
Growth stage update
Images: Apple varieties McIntosh (left) and First Kiss (right) are currently in silver tip and on their way to green tip in SE Minnesota. Photos taken at Sekapp Orchard in Rochester, MN.
Here in Southeast Minnesota, apple buds are progressing from dormancy through silver tip, and soon will be at the growth stage known as green tip. If you’re new to learning about apple growth stages, we recommend checking out this chart from Michigan State University. Growth stages line up with management recommendations.
It’s also helpful to understand how these growth stages relate to cold hardiness and how vulnerable a tree is to low spring temperatures. Typically, the further along a plant is in its growth and development, the more at risk it is to cold and freezing damage.
Critical spring temperatures for different apple growth stages where plants can experience 10% or 90% kill to buds and other anatomy.
Image: Chart showing critical temperatures (Tc) in which 10% and 90% frost damage leads to tissue death for apples at various growth stages (3). Note, these temperature listings are a generalization and not an exact threshold for all apple varieties. Information in this chart is derived from Michigan State University Extension resources.
Pest management considerations: When are copper and dormant oils used?
During this stage, copper fungicides/bactericides can aid in early management of apple scab and fire blight, when present, while dormant oil is primarily used to suppress early season mites and San Jose scales.
Fire blight is not as frequently an issue at bloom as fire blight strikes (shoot infection) in Minnesota. However, for orchards in warmer Minnesota regions, especially if fire blight was observed in 2025, early copper applications can be helpful. Other products used for fire blight management include products like Apogee and Actiguard (applied at pink).
When copper is applied closer to green tip, it can provide temporary protection against early apple scab infections for growers following organic management programs. Conventional growers have a broader range of options, which tend to be more effective than copper and will be discussed in our next Fruit Update article (more information provided in the Midwest Fruit Pest Management Guide starting on page 16).
There are multiple formulations of copper that can be used as a fungicide/bactericide (options listed on page 15 of the Midwest Fruit Pest Management Guide). Copper can be mixed with dormant oil when the oil is mixed at a lower rate (1% concentration) and best applied during dry conditions when temperatures are above 45°F. The risk of bud damage increases when freezing temperatures occur within 48 hours of an application. It is also important to understand that rain washing copper off of trees is actually helpful in reducing the risk of phototoxicity to growing tissues as they develop. When following best practices, copper applications should generally be avoided after tight cluster, although the risk of damage increases as growth stages advance beyond green tip.
Images: 1) An apple branch wrapped with reversed electrical tape within a population of San Jose scale (Diaspidiotus perniciosus), 2) using a jeweler’s lens to look closely, and 3) a magnified view of San Jose scale crawlers, which are the small yellow specks mixed among a cluster of scale coverings. Images taken by Kate Scapanski, UMN apple researcher at the UMN Horticulture Research Center (HRC.)
San Jose scale females can be identified by their shells that remain on the tree branches throughout the dormant season. This is the growth stage that can be targeted with dormant oil. While San Jose young (i.e., 1st instars), also known as crawlers, can be managed later in the growing season, they are at risk of developing resistance to insecticides, which is why dormant oil applications can be helpful if this is an issue in your orchard. Keep in mind that dormant oils work best with temperatures above 60°F because they become more biologically active with warmer temperatures.
Managing woody materials after pruning
Images: A flail mower can be used to chop up denser woody materials leftover from dormant pruning.
Annual, dormant pruning leaves behind a significant amount of woody biomass in orchard and vineyard settings that needs to be managed for various reasons. In the case of crops like grapes, where pruning materials can host fungal pathogens, they generally need to be taken off-site. It’s common for farms to burn prunings, which is recommended when it is necessary to reduce the risk of pathogen dispersal; however, this practice leads to a rapid release of carbon into the atmosphere and reduces the carbon sequestration benefits of perennial agriculture.
An alternative option to burning is the practice of flail mowing, which returns biomass to the soil surface and can contribute a modest amount of organic matter (OM) to orchard soils. To follow this practice, prunings should be raked into the aisle before the first mowing pass. Pruning materials shred best when conditions are dry and materials are dispersed rather than clumped into piles throughout the orchard aisles. Additionally, flail mowers are more effective for smaller diameter wood (between 1-1.5 inch in diameter).
Additional UMN newsletters to support your fruit production goals
Our newsletter is one piece of the knowledge and resources it takes to successfully produce fruit. Below are additional newsletters offered by the University of Minnesota to support you.
UMN Small Farms Newsletter - A newsletter to stay informed about events related to food production.
Minnesota WeatherTalk - WeatherTalk is a blog on climate and weather observations by retired University of Minnesota Extension climatologist and meteorologist Mark Seeley.
Cottage Food Safety News - Be alerted to articles related to cottage foods production and safety.
Thank you to our farm and ag professional partners for contributions to the UMN Fruit Update series. Non-credited photos in this article were taken by Madeline Wimmer.
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