Nursery Research Findings Nursery Research Findings and Education Initiativesand Education Initiatives

Jennifer ParkeJennifer Parke Oregon State UniversityOregon State University

Asymptomatic root infection (Shishkoff, Parke)Persistence in infested potting media (Linderman)Recovery from organic debris in nursery substrate (Dart and Chastagner)Inoculum production from infected roots (Shishkoff) or buried infected leaf disks (Tjosvold)

Belowground phaseBelowground phase

Nina Shishkoff, USDA- ARS Ft. Detrick, MD

Nina Shishkoff, USDA- ARS Ft. Detrick, MD

Sporangia and chlamydospore production from leaf disk in flooded conditions (one week, 20 o C, dark)

Greenhouse

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Weeks

Chl

amyd

ospo

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(mea

n pe

r lea

f dis

k)

-5

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45

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65

75

Spor

angi

a (m

ean

per l

eaf d

isk)

C dataC fittedC 95% LCLC 95% UCLS dataS fittedS 95%LCLS 95% UCL

Steve Tjosvold, UC Extension, Santa Cruz, CA

Differences in susceptibility among cultivars of rhododendron (Heungens, Grunwald), camellia (Shishkoff), lilac (Shishkoff), and viburnum(Grunwald)Effects of rhododendron cv. on pathogen epidemiology (Grunwald)Testing of rhododendron species for resistance to P. ramorum (Chastagner)Testing of nursery materials for use as disease-resistant border plantings (Shishkoff)

Host susceptibility/resistanceHost susceptibility/resistance

Host susceptibility to P. ramorumExperiment 1

Cultivar

VburkVplic

MarVlen

tago

VlantM

ohVopSter

i

VopCompaVden

tNBu

Vdent

VtrilW

enVden

tChi

VburkMoh

VdentA

utVplic

ShoVden

tBlu

VplicSha

Vdavidii

Lesi

on a

rea

(%)

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Experiment 2

Viburnum host

VburkVplic

MarVlen

tago

VlantM

ohVopSter

i

VopCompaVden

tNBu

Vdent

VtrilW

enVden

tChi

VburkMoh

VdentA

utVplic

ShoVden

tBlu

VplicSha

Vdavidii

Lesi

on a

rea

(%)

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60

• Identified viburnum and lilac cultivars that are resistant to P. ramorum

Nik Grünwald

USDA-ARS HCRL Corvallis, OR

Effect of cultivarCultivar LAa (%)

Sporangia/lesion

Sporangia/cm2 lesion

IP10b

(days)IP50c

(days)AULECd

Experiment 1

‘Boursault’ 17 a 46 a 15 a 1.6 b 2.1 b 74.23 a

‘Lee’ 6 b 17 b 12 a 1.8 a 2.6 a 44.33 b

Experiment 2

‘Boursault’ 19 a 287 a 68 a 1.6 b 1.8 b 84.81 a

‘Lee’ 8 b 139 b 78 a 1.8 a 2.0 a 52.34 b

Experiment 3

‘Boursault’ 11 a 83 a 36 a 1.6 b 2.2 b 62.52 a

‘Lee’ 4 b 25 b 31 a 1.7 a 2.5 a 35.31 b

Nik Grünwald

USDA-ARS HCRL Corvallis, OR

Susceptibility of Rhododendron spp. to P. ramorum

• Cooperative project with the Rhododendron Species Foundation with support from the WSDA Nursery Research Program.

• Testing 40 species that are native to Yunnan (China), commonly cultivated, and/or commonly used in hybridizing.

• Preliminary data indicates there is a wide range in susceptibility among the species being tested.

Several fungicides found effective for use on woody ornamentals (Linderman, Tjosvold, Chastagner)Documentation of widespread resistance to metalaxyl in EU (Werres, Heungens)

Fungicide effectivenessFungicide effectiveness

• Ongoing project that is supported by the IR-4 program.

• Screened 13 fungicides for their effectiveness in protecting rhododendron leaves from infection in 2007.

• Some fungicides reduced disease development on wounded as well as non- wounded leaves.

• On non-wounded leaves, the most effective fungicides were Stature, Maneb, Dithane, NOA 446510, Gavel, Polyram, Captan, and Segway.

• Some fungicides reduced infection up to 12 weeks after application.

Fungicide efficacy

Segway12 wks

Inoc. ck

P. ramorum present in recirculating water in nurseries (Werres)Slow sand filtration and lavagrain filtration effective in eliminating P. ramorum (Werres)Detection of Pr in streams near infested nurseries Abundance of Pr in streams appears to be related to temp and rainfall (Tjosvold)Relationship of waterborne propagules to disease (Werres, Tjosvold)

Water ecologyWater ecology

Ufer et al. Federal Biological Research Centre for Agriculture and Forestry Institute for Plant Protection in Horticulture, Braunschweig, Germany

Supernatant water

Filter Cover

Underdrain system (lowest level) with drainage for effluent

Filter surface (sand)

Slow Sand Filtration

Ufer et al. Federal Biological Research Centre for Agriculture and Forestry Institute for Plant Protection in Horticulture, Braunschweig, Germany

DetectionDetection of of PhytophthoraPhytophthora –– Sand Sand filtrationfiltration 11

Filtrated waterRetention basinRun off

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Bai

tlea

fpie

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hora

dete

ctio

n(%

, n=1

5 )

Aug2003

Oct May2004

Aug Oct May2005

Aug Oct May2006

Aug Oct

Sampling month

Stream Infective Propagules Statistical model using rain (4 day prior) and temperature (65 day prior)

Steve Tjosvold, UC Extension, Santa Cruz, CA

Predicted disease occurrence

max. cfu / l / pear LW hrs @ 2o-12o CPredicted_

#diseased_leaves95% CIlower

95% CIupper

0.05 18 0 0 1

0.1 17 0 0 1

0.2 16 1 0 2

0.3 15 1 0 3

0.35 14 1 0 3

0.45 13 2 1 4

0.55 12 3 2 6

0.65 11 5 3 9

0.75 10 9 5 16

0.85 9 10 5 20

0.9 8 18 8 40

7 days before detection (2 day period)

Steve Tjosvold, UC Extension, Santa Cruz, CA

Recognition of 3 clonal lineages in N. American nurseries (NA1, NA2, EU1)Comparisons on biology and epidemiology of clonal lineages is underway (Heungens, Grunwald)Genotyping of isolates from infested nurseries (Grunwald, Chastagner, and others)

Population biologyPopulation biology

• Cooperative project with WSDA and Nik Grunwald that is supported by the WSDA Nursery Research Program.

• EU1, NA1 and NA2 detected among 2005, 2006, and 2007 isolates.• NA1 most common.• Multiple genotypes and lineages commonly

found in single nurseries. • NA1 and EU1 lineages found on same plant

in 2007. • No evidence of sexual recombination. • Sammamish river isolate has rare fingerprint matching single

isolate from wholesale landscape supplier located outside of the watershed.

• Additional isolates from nurseries and two positive streams in WA are currently being genotyped.

Genotypes of P. ramorum in Washington state nurseries and streams

Characterization of temp and moisture conditions required for infection and/or sporulation (Grunwald, Tooley, Tjosvold)Dispersal in water and air: mock nursery (Heungens)Histological studies of infection (Werres)

Biology and epidemiologyBiology and epidemiology

Sporulation and infection

• Characterize conditions for sporulation and infection

• foundation for development of integrated P. ramorum management strategies

Sporulation

ExperimentExperiment 1 Experiment 2

Spor

ulat

ion

(spo

rang

ia c

m-2

lesi

on)

0200400600800

10001200140016001800

Minnetonka Boursault

Nik Grünwald

USDA-ARS HCRL Corvallis, OR

Disinfestation of nursery substrates with chemicals (Yakabe) and biological agents (Widmer)Effect of N fertilization on disease (Chastagner)Development of rapid, chip-based detection method for field use (Werres)Systems approach for identifying sources of contamination in nurseries (Parke & Grunwald)

Management and detectionManagement and detection

• 2008 cooperative project with WSU Horticulturist Rita Hummel that is supported by the WSU Emerging Research Issues grant program.

• Three cultivars (‘Compact P.J.M.’, ‘Cunningham’s White’ and ‘English Roseum’).

• Three nitrogen rates.• Assess infection, lesion

development and sporulation.

Influence of “N” fertility on the susceptibility of rhododendrons to P. ramorum

A Systems Approach for Identifying Sources A Systems Approach for Identifying Sources of of PhytophthoraPhytophthora Contamination in NurseriesContamination in Nurseries

Jennifer Parke and Carrie Lewis, Oregon State UniversityNik Grunwald, USDA-ARS Horticultural Crops Research Laboratory

4 nurseries, each sampled 6x/year 4 nurseries, each sampled 6x/year 4 plant hosts (4 plant hosts (PierisPieris, Rhododendron, Kalmia, , Rhododendron, Kalmia, ViburnumViburnum) at all stages of production year 1 and 2 ) at all stages of production year 1 and 2 Broadened to all Broadened to all PhytophthoraPhytophthora hosts in year 2hosts in year 2Also sampled potting media and components, Also sampled potting media and components, substrate, containers for resubstrate, containers for re--use, irrigation pond wateruse, irrigation pond waterGoal is to identify sources of contamination Goal is to identify sources of contamination and change management practices to and change management practices to alleviate the problemalleviate the problem

AA BB CC DD

PropagationPropagation plantplant -- -- -- --

substratesubstrate -- -- -- --

GreenhouseGreenhouse plantplant ++ ++ ++ ++

substratesubstrate ++ ++ ++ ++

Can yardCan yard plantplant -- ++ ++

substratesubstrate ++ ++ ++ ++

Potting medium/compPotting medium/comp ++ -- ++ ++

Used containersUsed containers ++ ++ ++ ++

Irrigation waterIrrigation water ++ -- ++ --

Recovery of Recovery of PhytophthoraPhytophthora species from nurseriesspecies from nurseries

PhytophthoraPhytophthora species identificationspecies identification

183 183 Phytophthora isolatesPhytophthora isolatesMost common species: Most common species: P. P. cinnamomicinnamomi (45),(45),P. P. syringaesyringae (21),(21), P. P. cryptogeacryptogea (21),(21), P. P. citrophthoracitrophthora (18),(18), P. P. citricolacitricola (16),(16), P. P. gonapodyidesgonapodyides (16),(16), P. P. megaspermamegasperma (1),(1), P. P. heveahevea (1),(1), unidentified unidentified Phytophthora spp. Phytophthora spp. (44)(44)

WSUWSU--WSDA programWSDA programOSUOSU--ODA programODA program

New Education InitiativesNew Education Initiatives

SOD Education: WSU and WSDA Hands on Nursery Training Pilot Study

• WSDA required all 2007 positive nurseries to attend.• Training in BMPs and symptom recognition.• 85% of participants report changing mgt. practices.• Course handbook available at:http://www.puyallup.wsu.edu/ppo/events.html

Plant storage evaluation Symptom recognition

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A. Sporangia* develop on infected leaf, detach, and are transported via wind or water splash.

B. Sporangia land on wet leaf, stem, or bud surface, and release zoospores which encyst, germinate and penetrate plant tissues

D. Chlamydospores persist in leafy debris from infected plants and germinate to form new sporangia or hyphae.

C. Zoospores towards rootsand colonize r

1 Sporangia produced on infected plants or plant debriswind or water splash to uninfected plants.

2 Leaves from infected but asymptomatic plants are usmaterial

3 Pathogen spreads from infected plants, leafy debrismedia via motile spores (zoospores) in ponded or stan

4 Pathogen-infested potting media leads to infection of ro

5 Pathogen is applied to plants via irrigation from cosources (i.e. surface water, recirculated water ponds, e

1

6 Pathogen is introduced from external sources such asforests.

* not drawn to scale

Phytophthora ramorum nursery disease cycle