Document Type



Master of Science (MS)


Environmental Studies

First Advisor's Name

Kateel Shetty

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Krishnaswamy Jayachandran

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Mahadev Bhat

Third Advisor's Committee Title

Committee member


Citrus Greening, Endophytes, Antimicrobial

Date of Defense



Citrus greening is an economically disastrous bacterial disease that infects all species of citrus, and currently has no cure. It is caused by Candidatus Liberibacter asiaticus (CLas), an unculturable phloem-limited bacteria vectored by the sap-sucking insect Diaphorina citri. Citrus greening has spread to every citrus-producing county in Florida; thus, there is a crucial need to develop environmentally safe treatments to reduce or eliminate CLas. It was hypothesized that endophytic microorganisms isolated from survivor citrus trees would show antagonistic activity against CLas; also, that plant extracts with known antimicrobial properties could suppress CLas. Oregano, thyme and turmeric extracts in the concentration of 1% and cell-free culture supernatants of endophytic isolates B-25, B-9, B-24 and B-27 at a concentration of 10% were found to be highly potent inhibitors of CLas. These results provide strong impetus for further characterization of endophyte and plant extracts, and their potential application as disease management tools for citrus greening.





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