minnesota high tunnel disease survey
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© 2012 Regents of the University of Minnesota. All rights reserved.
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High Tunnel Disease SurveySummary of results, management recommendations, and future research
DR. ANGELA ORSHINSKY
ASSISTANT PROFESSOR AND EXTENSION SPECIALIST
DEPARTMENT OF PLANT PATHOLOGY
UNIVERSITY OF MINNESOTA
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© 2012 Regents of the University of Minnesota. All rights reserved.
TODAY’S TALK
The MN High Tunnel Network Survey
– What it is
– What we found
Management of disease in high tunnels
– IPM
– Fungicides
Future of high tunnel disease research
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
MN High Tunnel Network Survey
USDA-MDA Specialty Crop Block Grant
Initially subsidized sample submissions to the
PDC – low response rate
Starting summer 2014 – sample 15+ high
tunnels across MN 3 times per year
Tomato, pepper, eggplant only
>200 samples collected and diagnosed this
summer
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Diagnosis of plant pathogens:
Macroscopic symptoms
Microscopy (fungi only)
Isolation of bacteria and fungi
Electron microscopy (viruses)
Test strips (viruses)
DNA isolation and sequencing
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY2013 results:
– Only 10 samples sent in to PDC despite
subsidy
Found:
– Impatiens necrotic spot virus on pepper (1)
– Leaf mold (5)
– Unknown (1)
– Fusarium root and crown rot (1)
– Herbicide injury (3)
– Early blight (1)
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
2014 results:
> 200 samples
• 100 % had leaf mold
• 100 % had early blight
• 90 % had gray mold
• Phoma fruit rot (1)
• Anthracnose (2)
• Bacterial spot (4)
• Bacterial speck (1)
• TMV/ToMV (3)
• White mold (3)
• Powdery mildew (5)
• Fusarium crown and root rot
(5)
• Septoria leaf spot (3)
• Late blight (1)
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYMFVGA 2014: Is leaf mold a problem in your high
tunnels?
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2015: Is leaf mold a problem in your high tunnels?
58%23%
10%
9%
I see it every year I see it some years
I have never seen it I am unsure
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
2014 high tunnel results
• Every high tunnel visited had
at least some leaf mold
• Many tunnels experienced
severe defoliation
• Severe cases had fruit
infection
• Seen as early as June in
northern Minnesota
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
2014 high tunnel results
• Severe cases often
ended up with multiple
pathogens
• Leaf mold Botrytis
Trichothecium
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© 2012 Regents of the University of Minnesota. All rights reserved.
TOMATO LEAF MOLD – PASSALORA FULVA
• Spore germination at 58 % RH,
optimal 75 – 90 %
• Sporulates 10-12 days after
infection
• Conidia survive “up to” one year
• Transmitted on seed, wind, rain,
equipment
• Survives as tiny bundles of cells
in leaf debris
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© 2012 Regents of the University of Minnesota. All rights reserved.
TOMATO LEAF MOLD – PASSALORA FULVA
Diagram from Dhou and Zhou. 2012.Cell Host and Microbe. 12: 484
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© 2012 Regents of the University of Minnesota. All rights reserved.
TOMATO LEAF MOLD – PASSALORA FULVA
Symptoms - Early
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© 2012 Regents of the University of Minnesota. All rights reserved.
TOMATO LEAF MOLD – PASSALORA FULVA
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© 2012 Regents of the University of Minnesota. All rights reserved.
TOMATO LEAF MOLD – PASSALORA FULVA
UMN Research
Research to determine
– What pathogen races are here = Cultivar recommendations
– Seed infection and treatment = heirloom growers
– Organic options and high tunnel fungicide options
– Timing of fungicide sprays
– Fungicide resistance
Research is only possible because of your
support!
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY2014: Has early blight been a problem in your
high tunnels?
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
2014 high tunnel results
• Found at every high tunnel
• Two different Alternaria species –
both were found.
• Stem infection, fruit infection, leaf
infection all found
• Found on tomato, pepper, and
eggplant
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© 2012 Regents of the University of Minnesota. All rights reserved.
EARLY BLIGHT – ALTERNARIA TOMATOPHILA,
ALTERNARIA SOLANI
Very common disease
Some resistant varieties
(resistance not complete)
Can cause severe yield loss
(fruit infection, defoliation)
Will infect nightshade weeds
Temperatures of 59-86 F
90 % humidity
Survives in soil, seed, debris
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Gray Mold – Botrytis cinerea
First observed in June
Severe damage by September
Loss of fruit, defoliation of
plants, stem lesions
Spores infect in 5 h with free
water, temperatures 65 – 75 F
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Powdery Mildew
Three types, only found one
type in MN this year.
Late season disease
Severe in overcrowded tunnels
Defoliation
Very aggressive pathogen
Wide host range including
weeds
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Fusarium Root and Crown Rot
Fusarium oxysporum fsp. radicis
lycopersici (FORL)
Up to 60 % loss at two
locations
Plants lost early in the season
Cool temperatures favor
disease
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYFusarium Root and Crown
Rot
3 + years tomatoes
Found on young pepper
plants at one location
No fungicide options
Resistant varieties
Need rotation!
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Fusarium Root and Crown Rot
Survives many years as chlamydospores in soil
VERY difficult to eliminate
Spread by water, people/clothing, infected pruning
tools
There are no fungicides for crown and root rot!
Cultural practices become that much more
important!
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Tobacco/Tomato Mosaic Virus
Leaves - mottled, small,
curled/distorted, plants stunted
Fruit - Distorted, uneven color, ripening
delay, brown discoloration of inner
walls
Common on ornamentals and weeds
Transmitted mechanically, seed,
survives tobacco curing and burning!
Photos: apsnet.org
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Photos: apsnet.org
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Tomato Spotted Wilt Virus
Leaf bronzing
Small darks spots on leaves
Streaks on petioles & stems
Spread by thrips
Photo: apsnet.org
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYBacterial Spot, Xanthomonas spp. Dark, water-soaked lesions on leaves that turn red-brown
Lesions often bound by leaf veins and on leaf edges/tips
Fruit lesions are raised, brown, ¼ inch diameter
Secondary fungal infections on fruit
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYOn our radar - Bacterial canker
Seed transmitted (5 yr survival)
Survives 2-3 yr in plant debris
Causes wilt of the plant
Causes fruit lesions (bird eyes)
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Other issues
Russetting of peppers
Caused by mites
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEY
Other Issues
Herbicide Damage
• Cupped leaves
• Twisted growth
• Thick leaf veins
• Veins close together
• New leaves most severely affected
• Survives composting process,
volatilizes
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYOther issues – Stink bug Damage
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© 2012 Regents of the University of Minnesota. All rights reserved.
MN HIGH TUNNEL NETWORK SURVEYInsect/Vector Management
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© 2012 Regents of the University of Minnesota. All rights reserved.
Management of High Tunnel
DiseasesSO WHAT DO WE DO WITH ALL OF THESE DISEASES?
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© 2012 Regents of the University of Minnesota. All rights reserved.
Pathogen
Host Environment
No Disease
No DiseaseNo Disease
No DiseaseNo Disease
No Disease
THE DISEASE TRIANGLE
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Integrated Pest Management (IPM)
Exclusion: Certified seed; seed
disinfestation; clean transplant; farm
traffic management
Plant Health: Site selection; choose appropriate
varieties; proper fertility
Cultural Management:
Sanitation, Humidity
control, rotation, mulch
Fungicides
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© 2012 Regents of the University of Minnesota. All rights reserved.
PLANT HEALTH
Site selection/preparation
– Light requirements
– Soils: pH, drainage,
organic matter
Variety selection:
– Disease resistance
– Temperature sensitivity
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© 2012 Regents of the University of Minnesota. All rights reserved.
PATHOGEN EXCLUSION Do not let the pathogens into your crop
Use certified, disease-free seed
Treat harvested seed
– Fermentation
– Hot water treatment
– Disinfectants
Transplants from trusted sources
Compost and mulch from trusted sources
Manage insect vectors
Physical barrier – plastic mulch
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© 2012 Regents of the University of Minnesota. All rights reserved.
CULTURAL MANAGEMENT Varieties with disease resistance
Sanitation
– Remove diseased plants or plant parts
– Disinfest tools, equipment
– Boots and clothing for your farm only
– Remove plant debris regularly
Humidity
– Allow for air flow by rolling up sides, vents, use fans
– Prune out lower canopy in the afternoon
Crop rotation
– Reduce the build up of pathogens
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SCOUTING BASICS
Pick a day and time each week
What is your disease history?
Know the biology of likely
pathogens
– What is a tolerable level?
– How fast can it progress?
Bring a tool kit
Establish a route for scouting
Inspect entire plant – flip leaves,
look at soil line and up
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SCOUTING TOOL KIT
Camera/smartphone
Notepad
Flagging tape
– Mark plants of interest
Bags
– Remove diseased plants
– Collect samples for diagnosis
Hand lens
Disinfectant
– Disinfect pruning tools and hands as you go
Disposable gloves
– If viruses a problem, don’t touch symptomatic plant then healthy one
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Typical IPM recommendations: when you achieve
an economic threshold
When you don’t have a threshold:
– What amount of the disease can you tolerate?
– Does this disease cause yield losses?
– Will the disease kill the plant?
– How quickly will the disease spread?
Fungicide resistance management:
– DO NOT wait until you have massive sporulation
Fungicides do not actually kill, they reduce growth
WHEN TO USE A FUNGICIDE
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Diagnose the disease
– Pdc.umn.edu; smartphone apps; compendia (apsnet.org)
You cannot treat abiotic, bacteria, and viral
diseases with fungicides!
Fungicides don’t work the same on all fungi
HOW TO CHOOSE A FUNGICIDE
pdc.umn.edu
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Once you have a
diagnosis:
– UMN Extension specialist
– Midwest Vegetable Production
Guide for Commercial
Growers
HOW TO CHOOSE A FUNGICIDE
mwvegguide.org
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Understand the label
What is the fungicide class?
What is a FRAC code?
Cross resistance
Adhere to restrictions on:
– # applications in a row
– Total # applications
– Suggested tank mixes
FUNGICIDE RESISTANCE MANAGEMENT
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Fungicide rotation– Rotating between fungicides from different classes.
Tank mixing
– Spraying two fungicides of different classes at the same time
– include one penetrant and one multisite, contact fungicide.
– Some combinations are phytotoxic and could result in plant injury.
Label restrictions reduce fungicide resistance,
environmental, and health hazards– maximum numbers of consecutive applications
– maximum number of applications per season
– maximum amount of product applied per season.
FUNGICIDE RESISTANCE MANAGEMENT
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Mode of action
– What cellular targets does the fungicide attach to?
– Mitosis, nucleic acid synthesis, cell wall synthesis
Mobility
– Contact: Don’t move from landing spot
– Penetrant: Moves past the cuticle into the plant
– Local penetrant, Acropetal penetrant, Systemic penetrant
FUNGICIDE CHARACTERISTICS
Contact Local Penetrant Acropetal Penetrant Systemic Penetrant
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GENERAL GUIDELINES FOR DISEASE MANAGEMENTWhat if you find something?
Diagnosis is key:
– Email or call a specialist or educator!
– Plant Disease Clinic: pdc.umn.edu
– Tomato MD
– UMN Extension website: www.extension.umn.edu
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ORGANIC OPTIONS
Biocontrols not tested at UMN yet
Will be tested in the next few years
Cultural management
Clean seed
ROTATION
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FINAL WORDS ON DISEASE MANAGEMENT Rotate out of Solanaceae to prevent disease build up
Remove heavily sporulating plant material
Reduce density of plants to reduce disease
Cultural management is worth the effort
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© 2012 Regents of the University of Minnesota. All rights reserved.
WHAT’S NEXT FOR HIGH TUNNEL RESEARCH? Last year of the survey is 2015
Continuing with leaf mold disease
research (2015-2017)
– What races are here?
– Resistant cultivars?
– Survival in high tunnels & sanitation practices
– Organic options? Fungicides?
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© 2012 Regents of the University of Minnesota. All rights reserved.
We depend on you for input and support:
We need your help to gather information to
help us help you!
– Participate in our survey (sign up)
– Let us know what your disease problems are!
Angela Orshinsky – aorshins@umn.edu
612-625-9274
WHAT’S NEXT FOR HIGH TUNNEL RESEARCH?
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© 2012 Regents of the University of Minnesota. All rights reserved.
The University of Minnesota is an equal opportunity educator and employer. In accordance with the Americans with Disabilities
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Thank you!Acknowledgements: Michelle GrabowskiTerry NennichVince Fritz
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