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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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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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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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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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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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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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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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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• Severe cases often

ended up with multiple

pathogens

• Leaf mold Botrytis

Trichothecium

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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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Diagram from Dhou and Zhou. 2012.Cell Host and Microbe. 12: 484

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Symptoms - Early

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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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MN HIGH TUNNEL NETWORK SURVEY2014: Has early blight been a problem in your

high tunnels?

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MN high tunnel Network survey2015: Has early blight been a problem in your high

tunnels?

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• 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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EARLY BLIGHT – SYMPTOMS

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EARLY BLIGHT – SYMPTOMS

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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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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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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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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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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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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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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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Photos: apsnet.org

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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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Photo: apsnet.org

Photo: apsnet.org

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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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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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Other issues

Russetting of peppers

Caused by mites

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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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MN HIGH TUNNEL NETWORK SURVEYOther issues – Stink bug Damage

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MN HIGH TUNNEL NETWORK SURVEYInsect/Vector Management

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Management of High Tunnel

DiseasesSO WHAT DO WE DO WITH ALL OF THESE DISEASES?

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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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PLANT HEALTH

Site selection/preparation

– Light requirements

– Soils: pH, drainage,

organic matter

Variety selection:

– Disease resistance

– Temperature sensitivity

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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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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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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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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 – [email protected]

612-625-9274

WHAT’S NEXT FOR HIGH TUNNEL RESEARCH?

mailto:[email protected]

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Thank you!Acknowledgements: Michelle GrabowskiTerry NennichVince Fritz

minnesota high tunnel disease survey

Education

northern minnesota

leaf debris

white mold

leaf moldmany tunnels

septoria leaf spot

root rot

crown rot

bacterial spot