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Statement on Botryosphaeria in Minnesota Grapevines

Authors: Annie Klodd, Matt Clark, and Mike White. With input from John Thull, Jenny Thull, Mizuho Nita, and Tim Martinson. 

During Dr. Richard Smart’s visit to the Horticultural Research Center on Monday, he discussed the common trunk disease botryosphaeria (“Bot canker”) and demonstrated it in several native and cultivated vines here. This fungal disease enters the vine through pruning cuts and injury, and gradually spreads through the vine over a number of years if not managed. It appears as brown streaks and cankers on the inside of woody tissue (xylem) (see photo).

Botrytosphaeria "bot canker" in a grapevine trunk

Signs of the disease are not visible in the current year’s growth. Additional pathological testing is required to determine which fungal organism(s) are present and causing symptoms as there are numerous Botryosphaeria species and other trunk diseases like Phomoposis and Eutypa that can have similar symptoms. This includes the classic wedge-like canker in mature vines.

Impact on Minnesota Vines 

Two important things to emphasize: 1) This trunk disease is not reason to panic, and grape growers around the world have been coexisting with it for many years. It is manageable, and does not warrant pulling out productive vines or cancelling orders. Energy should instead be focused on management. 2) It is unknown what percentage of vines Bot canker is present in, or what varieties are most susceptible. Research will be needed to determine the causal relationship between the presence of Bot canker and vine decline, including winter injury.

Bot canker is manageable through good sanitation after pruning, cordon replacement, and proper site selection. Bot that is not managed will eventually cause reduced yields, trunk die-back, and a shorter lifespan. These symptoms look similar to winter injury, and the two factors may be combining to lead to vine decline.

Botryosphaeria is common throughout the world, and grape industries in California, France, Italy, New Zealand, and others have successfully coexisted with it for quite some time. Now that we have a heightened awareness of this disease in Minnesota, we are able to improve our management practices in order to minimize its impact on our beautiful Minnesota vineyards.


Dr. Mizuho Nita is the grape pathologist at Virginia Tech who has been researching Botryosphaeria biology and management for many years. He is an authority on the subject. Here are some take-aways from a conversation with him this week:

1) Botryosphaeria is present in the air. It mainly enters vines through pruning wounds that are made when the air is humid, like after a rain. 
2) He recommends pruning during dry conditions, and then spraying Rally or Topsin-M  (fungicides) on the vines once the temperatures warm above freezing but before it rains.
3) Growers should grow up suckers to replace trunks and cordons if die-back occurs.
4) It infects the vine gradually over the course of 10-20 years. If vines are not stressed and they are managed well, they are often able to produce for years before showing decline. 
5) Vine decline due to Botryosphaeria is typically observed on older vines; it can exist in the vines for a long time without causing damage. The two times Dr. Nita has seen decline on 3-4 year old vines were instances when they were pruned right before a rain, in the shade. Those are classic examples of disease conditions.
6) If the vines experience winter injury, the Bot infection may get worse because the vine is less healthy and therefore less able to tolerate infection. 

When growers see vine decline in Minnesota, such as dead spurs, cordons,or trunks, this may be a combination of factors including Botryosphaeria, winter injury, management, and wet conditions. If you suspect Bot canker in your vineyard, the only way to truly confirm it is through lab analysis. Send a sample to the UMN Plant Diagnostic Lab, with a note that you suspect Botryosphaeria. Then if it is confirmed, follow the above recommendations about training up new suckers and replacing cordons as needed. Practice preventative measures including spraying Rally and Thompson after pruning (once temperatures are above freezing), and removing pruning debris  from the field. Do not prune in wet conditions.

In addition, make sure that vines are grown in ways that minimize stress: Prune to the recommended spur counts for the variety, plant cold-hardy and disease-resistant varieties, and plant in well-drained sites (avoid planting in wetland and low-lying flat areas).

Stay tuned for further information. This is a new disease problem that has been brought to our awareness. Awareness is the first step in solving a problem.  Further research and experience will shed more light on dealing with this disease in our cold climate region. 

Please contact us with questions or if would like to discuss recommendations. Extension Educator Annie Klodd can be reached at

Publish Date: 
Friday, June 29, 2018 - 3:45pm

10th Anniversary ICCWC

10th Anniversary International Cold Climate Wine CompetitionRegistration is now open for the 10th Anniversary International Cold Climate Wine Competition. To submit your wines for the competition, click here!

Publish Date: 
Saturday, June 2, 2018 - 10:45am

VitiNord2018 Registration is Open!

VitiNord2018 will be hosted in the beautiful cities of Malmö/Alnarp – Copenhagen/Frederiksberg

July 30 through August 3, 2018

For the first time, an international conference will bring together growers and wine makers from the Scandinavian countries, Europe and North America. The Oresund bridge makes possible this conference in Sweden and, just across the Oresund, in Denmark.

Learn more about VitiNord2018 and register for this event at 

Publish Date: 
Wednesday, May 30, 2018 - 7:15am

Minnesota Grape Production Statistics 2017

Minnesota Grape Production Statistics 2017

Estimates for the yield, production, and pricing data of the minnesota grape industry

In early 2018, commercial grape growers in Minnesota provided University of Minnesota Extension with yield and pricing data for their 2017 harvest. Using an online survey instrument, growers reported on their planted and producing acres, and the yields, sales, and prices received for each cold-hardy grape variety. Additionally, growers reported on the causes and amount of crop loss experienced. Survey findings are summarized in the attached report.

Publish Date: 
Wednesday, May 23, 2018 - 11:00am

Richard Smart to Visit Hort Research Center on June 25

Improve Canopy Management and Reduce Disease with Dr. Richard Smart

The University of Minnesota and SMWGA will be hosting world renown viticulturist Dr. Richard Smart for a seminar, "Improved Canopy Management and Trunk Disease Implications for the Midwest" on June 25th, from 3-5pm at the UMN Horticultural Research Center. The seminar will be followed by a meet and greet reception from 5-6pm with Dr. Smart, featuring Minnesota wine and appetizers.

Dr. Richard Smart

To register: The event is $35, or $30 with a SMWGA membership. Please pre-register for this workshop in order to help us account for refreshments and seating. To RSVP, call or email Lisa Smiley at 651-492-5393 or

The event will take place at the Horticultural Research Center, 600 Arboretum Blvd, Excelsior, MN.

About Dr. Richard Smart: 

With over 40 years of experience consulting with viticulturists and winemakers around the globe, Dr. Smart is a global leader on vineyard management techniques. He is also the author of the book Sunlight Into Wine, viticulture editor of The Oxford Companion to Wine, and co-developer of the Smart-Dyson Trellis system. He has worked extensively to study and communicate how canopy management practices impact wine quality and yield, as well as how changing climates may impact the global wine industry into the future. 

Publish Date: 
Tuesday, May 22, 2018 - 9:00am

Learn to Plant a Vineyard with First-Hand Experience

Have you been thinking about starting a vineyard or a small grape planting? The best way to learn what it takes to start a vineyard is to help out at another established vineyard. However, these opportunities do not come along every day.

Fortunately, The Winery at Sovereign Estate is planting a new vineyard on June 16 and is offering free lunch and a viticulture class in return for helping to plant grapevines for a couple of hours! It will be a great learning opportunity for the beginner vintner, hobby grower, or someone looking to brush up on their skills before expanding their current vineyard. Details:

Vineyard Planting Outing – You’re Invited!

The Winery at Sovereign Estate and the University of Minnesota Extension viticulture program would like to invite you to a free vineyard planting outing.

Saturday, June 16th from 8:00am-2:00pm

The Winery at Sovereign Estate

9950 North Shore Road, Waconia, MN 55387

Start with a “classroom” lesson from the U of M’s Extension horticulturist, Annie Klodd, who will describe site selection, soil preparation, planting orientation, and planting…of course.

Then, put that new knowledge into action and head to the field where you will get to experience planting a vineyard of Marquette vines

Please RSVP by clicking the link below


Or email

Lunch and refreshments will be provided. Bring gloves and dress for the outdoors.

Hope to see you there!

Publish Date: 
Friday, May 18, 2018 - 1:15pm

Minnesota Research in the News

Dr. Richard Smart Monday June 25 at the Arboretum


Dr. Richard Smart:

Improved Canopy Management and Trunk Disease Implications for the Midwest


You are invited to a seminar and meet & greet with Richard Smart, global leader on vineyard canopy management techniques and author of Sunlight into Wine.

Dr. Smart will be speaking at the Minnesota Landscape Arboretum on Monday, June 25 from 3-5pm. A wine reception and refreshments with Dr. Smart will follow from 5-6pm. Registrations required. Clicke below to see the full flyer.

PDF icon Learn More Here!


Publish Date: 
Wednesday, May 16, 2018 - 4:30pm

Grapevine Pruning and Vineyard Prep Workshop April 21


Grapevine Pruning and Vineyard Prep Workshop

Get ready for the 2018 season with the Southern Minnesota Wine Grower Alliance and University of Minnesota Extension!

grape vineyard pruning cuttings on ground in pile

Visit the vineyard of Keith and Lisa Smiley to learn best practices for pruning vines on VSP and high cordon, managing winter injury, and choosing between training systems. Then get hands-on experience taking soil samples and evaluating vineyard health.

When: Saturday April 21, 10:00am-noon

Location: 10500 310th Street Way, Cannon Falls, MN 55009

Cost: $10/person


Annie Klodd, U of MN Extension Educator-Fruit and Vegetable Production

Lisa Smiley, Executive Director, Southern MN Wine Grower Alliance

Coffee and donuts included!

To register, contact Lisa Smiley at or 651-492-5393. You can also register at the event starting at 9:30am. Registration is $10/person. Make checks payable to SMWGA. Checks can be mailed to 10500 310th Street Way, Cannon Falls, MN 55009.

Getting to the vineyard: 10500 310th Street Way Cannon Falls, MN 55009 (Google maps link)


UMN Extension

Publish Date: 
Thursday, April 12, 2018 - 3:30pm

Clink! Sip + Savor Wine Market

Explore locally produced Wines and Food at clink!  UMN Grape Breeding and Enology staff will have a booth and will present a short talk at 4pm!

Clink Sip & Savor WIne Market 2018

Publish Date: 
Thursday, April 12, 2018 - 4:15pm


Registration is now open for the 9th Annual International Cold Climate Wine competition. Click on the logo to learn more.


Winter is Minnesota can be one of the most challenging times for the grape plants.  It's the main reason V. vinifera varieties aren't grown here.  Learn a little bit about whats going on in the vineyard in winter.

Wine making is a rewarding career, but is not free from headaches. A wine maker's nightmare is the re-fermentation of sweet wines and the instability of some wines. This blog entry addresses the topic and offers some strategies to avoid and mitigate a potential devastating re-ferment.


Are you curious if your wine is finished with malolactic fermenation? Here is a quick reminder on how to test with paper chromatography





ALERT: September 27, 2016. Spotted Wing Drosophila (SWD) in Grapes: A short memorandom on SWD in Minnesota and associated volatile acidity. Read more here

Fall vineyard managment should focus on managing insects, vertebrate pests, rots, and diseases that will impact the vines in the next growing season.  Making quality wines requires disease intervention and sorting, as infected fruit will impact wine quality. Read more here.


International Cold Climate Wine Competition 2016 Results here!

Northern Grapes Project Webinar Registration

“From Vine to Glass: Understanding the Flavors and Aromas of Cold-Hardy Grapes and Wine”
Tuesday, May 17th*, 2016
12:00 Noon Eastern (11:00 am Central)
7:00 pm Eastern (6:00 pm Central)
*Please note this is a date change from the original date of May 10th.

Join Anne Fennell of South Dakota State University, Adrian Hegeman of the University of Minnesota and Somchai Rice of Iowa State University as they discuss their research conducted on Marquette and Frontenac as part of the Northern Grapes Project. 

Mock Winery Inspection

Friday April 29, 2016


Savor Minnesota

This Saturday April 16, 2016


Itasca Grape Vine Named

The University of Minnesota releases its news wine varieity 'Itasca' on April 4, 2016


Intergeneric Grafting

Experimenting with different grafting techniques including grafting Ampelopsis with a hybrid rootstock.

Preliminary Bud Survival Data

Early bud chop counts on cold-hardy cultivars at the HRC


Old blog entries

Are you looking for previous blog posts? Search the archived entries