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Control of Phytophthora Diseases on Floral Crops. Dr. Mary K. Hausbeck Department of Plant Pathology Michigan State University. Control of Phytophthora and Botrytis Diseases,and Deer and Rabbit Herbivory of Floral and Nursery Crops. ARS Project Number: 1907-22000-016-02. Project Objectives.
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Control of Phytophthora Diseases on Floral Crops Dr. Mary K. HausbeckDepartment of Plant Pathology Michigan State University Control of Phytophthora and Botrytis Diseases,and Deer and Rabbit Herbivory of Floral and Nursery Crops. ARS Project Number: 1907-22000-016-02
Project Objectives • Identify the major Phytophthora spp. affecting floriculture production and determine which aspects of Phytophthora’s life history contribute significantly to control failure. • Develop durable production strategies for preventing and eliminating diseases caused by Phytophthora on floriculture hosts. • Screen novel agents for their potential as management tools for the control of Phytophthora crown and root rots.
Phytopthora spp. Characterization • Phytophthora spp. were recovered from eight floricultural hosts at eleven different facilities. • The isolates were identified to species using standard morphological traits and by comparing ITS regions (I & II) to the GenBank DNA database. • Isolates were characterized by comparing compatibility type and mefenoxam sensitivity and by analyzing AFLP fragments.
Summary data for Phytopthora spp. collected from floriculture production facilities.
Phytophthora Characterization Results • Phytophthora drechsleri was the dominant pathogen of poinsettias. • Phytophthora nicotianae was the most frequently isolated pathogen for other crops. • Both compatibility types were found for Phytophthora nicotianae.
Phytophthora Characterization Results • Phytophthora nicotianae isolates were identified that were resistant to mefenoxam. • Within a facility, Phytophthora epidemics were the result of a single clonal lineage.
Rate/100 gallons 21 day interval
Untreated Untreated Inoculated Untreated Uninoculated
Acrobat 50WP Acrobat 50WP 6.4 oz/100 gal Untreated Uninoculated
Subdue MAXX 21.3 EC Subdue MAXX 21.3EC 1.0 fl oz/100 gal Untreated Uninoculated
Truban 30WP Truban 30WP 10.0 oz/100 gal Untreated Uninoculated
Rate/100 gallons 14 day interval
Rate/100 gallons 14 day interval
Untreated Untreated Uninoculated Untreated Inoculated
Acrobat MZ 69WP Acrobat MZ 69WP 1.75 lb/100 gal Untreated Inoculated
Subdue MAXX 21.3EC Subdue MAXX 21.3EC I.0 fl oz/100 gal Untreated Inoculated
Results and Potential Value • An understanding of mefenoxam sensitivity has reduced growers’ costs by encouraging alternative management measures in situations where resistance has become an issue. • Dimethomorph, mefenoxam and etridiazole have all shown promise in the control of Phytophthora diseases.
Technology Transfer • Publication in trade magazines and professional journals. • Publication in on-line newsletters. • Presentation at grower meetings.
Project Team • Dr. Mary Hausbeck (Michigan State University) • Dr. Steve Wraight (Cornell, USDA-ARS) Contributors to Research • Dr. Kurt Lamour • Jeffrey Woodworth • Blair Harlan • Nicole Werner • Amanda Gevens • Matthew Bour • Pavani Tumbalum
Additional Funding Sources • IR-4 Ornamental Trials on Phytophthora, 2002. $2,000.