Infectivity of Conidia of Peronospora tabacina After Freezing and Thawing. Yigal Cohen, Department of Plant Pathology, University of Kentucky, Lexington 40546. Joseph Kuc, Department of Plant Pathology, University of Kentucky, Lexington 40546. Plant Dis. 64:549-550. Copyright 1980 American Phytopathological Society. DOI: 10.1094/PD-64-549.

Conidia of Peronospora tabacina, the incitant of tobacco blue mold, attached to infected leaves or suspended in aqueous suspensions remained infective for more than 3 mo at –20 C. Conidia on sporulating lesions survived after six repeated cycles of freezing (–20 C) and thawing (25 C), whereas conidia suspended in water survived after two such cycles. Conidia on sporulating lesions stored at 5 C (100% RH) survived more than 34 but less than 57 days. The possible epidemiologic implications of this feature of the pathogen are discussed.