Date of Award

12-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Plant and Environmental Science

Advisor

Jeffers, Steven N

Committee Member

Martin , Samuel B

Committee Member

Wells , Christina E

Committee Member

Bridges , William C

Abstract

Phytophthora foliage blight of garden phlox (Phlox paniculata ) - caused by Phytophthora nicotianae - is a devastating disease that has been seen consistently in nursery production facilities in South Carolina. However, this disease has not been characterized previously. This project was composed of three separate studies, each of which followed one of the three major components of the disease triangle (i.e., the synchronous occurrence of a susceptible host and a virulent pathogen within a conducive environment) to investigate the pathogenicity of P. nicotianae on P. paniculata . In one study, the efficacies of three inoculation methodologies to cause Phytophthora foliage blight and reproduce symptoms similar to those seen in the nursery on P. paniculata plants were evaluated. It was concluded that propagules of P. nicotianae must be present on foliage of garden phlox plants in warm, humid conditions for longer than 24 h for disease to occur consistently. In another study, variation in susceptibility among cultivars of P. paniculata was evaluated with two methodologies: a detached-leaf assay and a whole-plant assay. Both methods were effective in determining differences in susceptibility of cultivars of garden phlox to infection by P. nicotianae . It was also shown that wounding resulted in significantly greater susceptibility to infection. The final study in this project confirmed that isolates of P. nicotianae recovered from P. paniculata differ in virulence on cultivars of P. paniculata .

Share

COinS