U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 close



Research
                Research Home
                            National Programs
                            Research Projects
                            Scientific Manuscripts
                            International Engagement
                            Scientific Software/Models
                            Databases and Datasets
                            Office of Scientific Quality Review
            Media
                News & Features
                            Multimedia
                            Briefing Room
                            Down on the Farm
                            Press Room
                            Science in Your Shopping Cart
                            Scientific Discoveries
                            Tellus
                            Under the Microscope
            About ARS
                About ARS Home
                            Staff Directory
                            Labs and Research Centers (Map)
                            Headquarter Offices
                            Organizational Chart
                            Employee Services (REE Employees Only)
                            Office of Outreach, Diversity, and Equal Opportunity
            Work With Us
                Work With Us Home
                            ARS Vacancies at USAJOBS
                            Careers at ARS Information
                            Scientific Collaborations
                            Extramural Agreements
                            1890 Faculty Research Sabbatical ProgramSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Jones, Richarditem
                                            Stommel, Johnitem
                                            Wanner, Leslie
  Submitted to: Plant Disease
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/24/2009
                                    Publication  Date: 11/1/2009
                                    Citation: Jones, R.W., Stommel, J.R., Wanner, L.A. 2009. First report of Oidiopsis taurica causing powdery mildew outbreak on pepper in Maryland. Plant Disease. 93:1222.Interpretive Summary: While there are many diseases that affect plants, they may be present only in certain parts of the world.  When a disease appears in a new location, scientists document the occurrence so others can become aware of the potential for the disease in a new location.  We identified the first occurrence of a foliar disease called powdery mildew on pepper plants.  Reports of a new disease aid in determining how the disease causing organism appeared at the new location.  This information is used by growers to aid in controlling plant disease.
                                Technical Abstract: Pepper plants grown in large experimental plots at Beltsville Maryland showed widespread powdery mildew infection in the late summer of 2008.  Extensive coverage of the abaxial surface by white patches of conidia was noted, along with chlorotic regions on the adaxial surface. Samples were taken for DNA extraction and subsequent PCR amplification of the ITS regions (1).  The amplified band was cloned and sequenced, verifying the pathogen as Oidiopsis taurica (teleomorph Leveillula taurica).  Multiple chili pepper and bell pepper plants were inoculated with conidia from an infected bell pepper plant by placement in a spore deposition chamber.  Signs of powdery mildew were evident three weeks after spore deposition.  DNA samples were again analyzed and verified as O. taurica (deposited as GenBank #GQ167201). 
Powdery mildew infection was observed in a diversity of pepper accessions that included Capsicum annuum, C. baccatum, C. chinense and C. frutescens.  The C. annuum accessions included culinary bell pepper cultivars and breeding lines as well as a diverse collection of ornamental breeding lines, heirlooms and land races.  Infection was widespread in field plots and host resistance within any single species or ideotypes was not evident.  Disease occurred with equal severity in plants with open or compact and upright or prostrate growth habits, again suggesting a new, more aggressive isolate than that found in other studies (2).  The unexpected occurrence of powdery mildew on pepper in Maryland allowed widespread infection to occur prior to recognition of the emergent disease.  Significant leaf damage was incurred leading to partial defoliation where infection was most severe.  Application of Quadris (azoxystrobin) was effective in limiting further crop damage.  Subsequent powdery mildew infection was identified on pepper under greenhouse conditions during the winter of 2008.  Application of Strike (triadimefon) provided effective control in the greenhouse. 
This disease is new to the mid-Atlantic region of the U.S. It has been reported in greenhouse peppers growing in Ontario, Canada, where it has become a recurring problem requiring fungicide intervention (3).  The isolate we are reporting may be more virulent on pepper, as nearby tomatoes did not show evidence of infection.
No cleistothecia were found on infected leaves. Given the wide host range of O. taurica and the systemic nature of infections, it is likely that the fungus has become established in Maryland on perennial host plants.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov