Characterization of the bacterium serratia marcescens and management of squash diseases
Matteen, Zachary Thomas
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Cucurbit yellow vine disease (CYVD), caused by the squash bug-transmitted bacterium Serratia marcescens, causes vascular wilting and plant death. The goals of this thesis research were to 1) Characterize differences between CYVD strains and the closely-related strain R01-A; 2) Develop a reliable pathogenicity test which reproduces full disease symptoms; 3) Determine if biocontrol agents could suppress squash diseases; and 4) Evaluate which winter squash cultivars grew best in Georgia and whether cultivars differed in CYVD susceptibility. Sequence differences between CYVD strains and R01-A were identified and belong to a clade which may be a different species from other S. marcescens strains. An inoculation method using squash bug nymphs was comparable to needle inoculation and improved upon previous vector studies. Strains with antagonistic ability were identified, but biocontrol treatments had no effect in vivo. Several Cucurbita moschata cultivars performed well and differed in CYVD susceptibility.