Masters Theses

Date of Award

8-2018

Degree Type

Thesis

Degree Name

Master of Science

Major

Entomology and Plant Pathology

Major Professor

Mark T. Windham

Committee Members

Mohammad Reza Hajimorad, Frank A. Hale, John B. Wilkerson, Alan S. Windham

Abstract

Rose rosette disease (RRD) is an epidemic that is lethal to roses. The causal agent for this disease is thought to be rose rosette virus (RRV) which is vectored by an eriophyid mite, Phyllocoptes fructiphilus. Our research was aimed at answering fundamental ecological aspects of the relationship this mite shares with its rose hosts. In Chapter I, Rosa species were evaluated for levels of residential populations of P. fructiphilus. Statistical differences for year and rose species (α = 0.05) were observed. However, the resolution of the statistical tests was low due to loss of replications from destructive sampling of slow growing plants, development of symptoms of RRD, differential rates of mite populations on symptomatic vs asymptomatic plants of the same Rosa species, and variable tolerance of Rosa species to RRV. Chapter II involved a survey in Alabama, Georgia, and Mississippi for both vector and virus. A line was found through the middle of the three states where RRV was not detected south of the line. The southern border for P. fructiphilus was much farther south than the RRV line in each state. Many sites contained eriophyid mites other than P. fructiphilus. Eriophyes eremus was observed in all three states and is a new report for Alabama and Mississippi. The reasons for the lack of RRV and low populations of P. fructiphilus in the parts of these states are unclear. In Chapter III, the importance of floral cuts for maintaining eriophyid mite populations on field samples was evaluated. There were no significant effects of floral cuts or rose species observed. Rose rosette virus infected rose cuttings had an average of 46 times more eriophyid mites per gram of tissue than did cuttings from non-infected plants.

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