IR-4: Overview of research for

invasive pathogens of ornamental horticulture

crops

Cristi L Palmer, PhD

IR-4 Ornamental Horticulture Program Manager

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IR-4 Mission

Facilitate registration of sustainable pest management technology for specialty crops

and minor uses

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IR-4 Activities on behalf of the Green

Industry:Coordination of

research teams for invasive species

Photos by Cristi Palmer

Photo by Cristi Palmer

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Projects

• Gladiolus Rust (FY2010 – 2012)

• Chrysanthemum White Rust (FY2011 – 2014)

• Arthropod Shipping & Duponchelia fovealis(FY 2011 – 2013)

• Boxwood Blight (FY2012 – 2015)

• Impatiens Downy Mildew (FY2013 – 2015)

Boxwood Blight

Research TeamDr. Anton BaudoinDr. Mike BensonDr. JoAnne CrouchDr. Mark CubetaMr. Norm DartMs. Margery DaughtreyDr. Sharon DouglasDr. Ann Brooks GouldDr. Chuan HongDr. Kelly IvorsDr. Jim LaMondiaDr. Bob MarraDr. Nina ShishkoffDr. Oney Smith

Photo by Cristi PalmerLocation: Williamsburg, VADate: 9/5/2014

Boxwood Blight

Photo by Cristi PalmerLocation: Hightstown, NJDate: 9/5/2014

Research Goals• Fungicide screening and mitigation

strategies• Cultural control potentials• Effect of sanitizers on conidia and

mycelia• Impact of fungicides on

microsclerotium development• Screening of potential biopesticides

for microslerotium inactivation

Boxwood Blight

• Development of isothermic LAMP detection assay

• Boxwood species and cultivar screen for resistance

• Cps host range (Pachysandra and Sarcoccoca)

• Development of infections under field conditions

• Calonectria pseudonaviculata population genetics

• Development of epidemiology model based on U.S. temperature and moisture conditions

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Boxwood Blight Project Summary• Mitigation:

– Fungicides: chlorothalonal and chlorothalonil plus other fungicides yielded most consistent results

– Sanitizing Agents: most common sanitizers inhibit mycelial growth (not ethanol) and reduce conidial germination; ethanol was very effective at reducing germination of microsclerotia.

– Heat Treatment: heat can inactivate mycelia and spores, but flaming is not effective when propagules are buried below ground in nursery-like settings; hot water treatments are continuing to be explored

– Biological Control: Trichoderma species have been isolated and screened for activity

– Host Resistance: numerous cultivars and species have been screened and ranked from susceptible to (mostly) tolerant

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Boxwood Blight Project Summary, Cont.

• Biology: – Calonectria pseudonaviculata does not survive below -10C and above

30C

• Genetic Analysis: – Boxwood blight caused by two species (validated with biological and

morphological characteristics): C. pseudonaviculata and C. henricotiae– C. pseudonaviculata is the only species currently present in the US

• Detection:– Real time PCR primers were developed to distinguish the two species– Isothermic LAMP assay with color visualization was determined not to

be a viable fast detection method outside a laboratory– Development of ELISA based detection tool is ongoing

Boxwood Blight

Research Team

Dr. Mo Bonde

Dr. JoAnne Crouch

Dr. Kurt Heungens

Dr. Doug Luster

Dr. Oney Smith

Dr. Bas Brandwagt

Photo by Cristi PalmerLocation: NCDate: 8/7/2009

Chrysanthemum White Rust

Electron Micrograph by Dr. Gary Bauchan

Research Goals• Presence of latent infections• Overwintering capacity• Fungicide efficacy in planta• Baseline fungicide sensitivity for

US isolates• Host range and susceptibility

Chrysanthemum White Rust

• Development of CWR infections

• Determine upward mobility of P. horiana from infected crowns

• Compare US isolates to European isolates

• Validation of genetic diagnostic tools

• Development and validation of serological diagnostic tool

Boxwood Blight

Research Team

Dr. JoAnne Crouch

Ms. Margery Daughtrey

Dr. Mary Hausbeck

Dr. Lina Quesada

Dr. Aaron Palmateer

Dr. Nina Shishkoff

Photo by Cristi PalmerLocation: Cream Ridge, NJDate: 8/20/2014

Impatiens Downy Mildew

Boxwood Blight

Photos by Margery Daughtrey

Research Goals• Overwintering of Plasmopora

obducens oospores• Fungicide screening and

rotational strategies• Sporangia and oospore

development and epidemiology• Plasmopora obducens population

genetics• Development of genetic tools for

downy mildews including Impatiens Downy Mildew, Cucurbit Downy Mildew, Hops Downy Mildew, Basil Downy Mildew

Impatiens Downy Mildew

Boxwood Blight

Research Team

Dr. Mo Bonde

Dr. James Buck

Dr. Steve Jeffers

Dr. Doug Luster

Dr. Keithanne Mockaitis

Dr. Oney Smith

Dr. Alberto Valencia-Botin

Photo by Terry Davis

Gladiolus Rust

Photo by: Cristi PalmerLocation: Fort DetrickDate: 5/14/2014

Research Goals• Fungicide efficacy in the

field• Fungicide in vitro efficacy• Gladiolus cultivar

resistance• Urediniospore survival

Gladiolus Rust

• Systemic latent infection

• Develop serological diagnostic tools

• Develop genetic diagnostic tools

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Gladiolus Rust Project Summary

• Mitigation:

– Eighteen fungicides solo and in combination were screened for efficacy in gladiolus field located in several states in Mexico

– Most fungicides prevented or reduced spore germination (exceptions: epoxiconazole & cyproconazole)

– Gladiolus cultivars exhibited varying susceptibility to disease development but this was not correlated to flower color

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Gladiolus Rust Project Summary

• Biology:– Urediniospores did not survive buried in field soil for 30 or 45

days

– By 13 weeks under constant conditions (warm or cool and damp or dry), urediniospores germination dropped to nearly 0

– Corms harvested from infected plants did not exhibit symptoms after storage and regrowth

• Diagnostic Tools:– Polyclonal antibodies were developed against germinating

urediniospores

– Polyclonal antibodies were also generated from recombinant proteins chosen from cDNA libraries

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Summary

• IR-4 has facilitated 5 projects on invasive species since 2010

• These projects are consistent with IR-4 mission to facilitate registrations for growers, but they go well beyond in studying pathogen/pest biology, diagnostic tools, and population genetics in addition to mitigation

• IR-4 role to facilitate these research collaborations has benefited and will continue to benefit growers

Thank you ! Funding for IR-4 Research:USDA-NIFAUSDA-ARSUSDA-APHIS

Land Grant Institutions

Researchers:

All the fine researchers in the US and internationally!

IR-4 Personnel:Susan

BierbrunnerMichelle FooEdith LurveySatoru Miyazaki

Marylee RossMika Pringle-

TolsonBecky SiscoEly Vea

Invasive species activities were partially supported by USDA-APHIS-CPHST through the FY2011, FY 2012, FY2013, and FY2014 Farm Bills.

Thank you !Photo by Cristi Palmer