Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Plant and Environmental Science

Committee Chair/Advisor

James E Faust

Committee Member

Guido Schnabel

Committee Member

Christopher Saski

Committee Member

William C. Bridges


Botrytis blight caused by the fungus Botritys cinerea is the most devastating disease of cut roses. The extensive use of fungicides used for Botrytis blight management during cut rose production and postharvest represents a severe threat in terms of fungicide resistance development as has been previously reported. Additionally, health concerns for growers and the environment are growing in recent years making consumers more aware of the fungicides in the products that they consume including ornamentals. This scenario highlights the importance of searching for alternative products to synthetic fungicides. During this research, the use of calcium as an alternative management strategy was evaluated when used as a flower spray during greenhouse production (0, 500, 1000, and 1500 mg.L-1) or as a postharvest treatment (0, 1000, and 2000 mg.L-1, with and without coadjuvant). Additionally, natamycin postharvest dips alone and in combination with coadjuvant and calcium were assessed. Our results show that calcium sprays during production reduced Botrytis blight severity when applied at 500 and 1000 mg.L-1, but these spray applications did not result in an increase in the calcium concentration in the petal tissue. Postharvest calcium dip treatments at 2000 mg.L-1 were effective to decrease botrytis blight severity, increase calcium concentration in the petal tissue, increase the petal tissue to rupture, and were involved in the regulation of metabolic pathways involved in the activation of disease resistance mechanisms. Natamycin dips appear to be effective for several cultivars when applied at 500 mg.L-1.However, the best response was obtained when applied in mixtures with calcium. These two products used alone or in combination can provide an additional tool for an integrated disease management program which at the same time helps implementing effective fungicide resistance management strategies to reduce fungicide resistance development by potentially decreasing the amount of fungicide applications required in the greenhouses and during the postharvest of cut-roses.

Author ORCID Identifier




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