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United States Department of Agriculture

Agricultural Research Service

Title: Distinguishing Isolates of Peronospora Tabacina from Geographic Regions Utilizing Tobacco Leaf Disks and Fluorescence Microscopy

Authors
item Wiglesworth M D, - CIBA PLANT PROTECTION
item Nesmith W C, - PLANT PROT.,U OF KENTUCKY
item Siegel M R, - PLANT PROT.,U OF KENTUCKY
item Bonde, Morris
item Main C E, - PLANT PATH., NC STATE

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 1, 1994
Publication Date: N/A

Interpretive Summary: A standardized bioassay utilizing leaf disks from different tobacco cultivars was developed which allows laboratory comparison of the tobacco blue mold pathogen in different regions of the world. The technique provides a method to track changes in populations of the pathogen and alert growers to potential disease problems. It allows the determination of the source of inoculum that could cause devastating blue mold epidemics. Furthermore the technique with minor modifications, could be adapted for other pathogens, such as that which causes late blight of potato

Technical Abstract: A laboratory bioassay to distinguish isolates of Peronospora tabacina D.B. Adam was developed utilizing 7-mm acetone-dipped disks cut from tobacco lea panels from several cultivars of Nicotiana tabacum, sporangiospores of P. tabacina, a germination indicator (Calcofluor), and fluorescence microscopy Sporangiospore germination percentage of each isolate X cultivar pair was determined. Mean germination of sporangiospores differed between domestic and international collection locations (except between the two Mexican isolates). These results suggest the presence of different pathotypes of P. tabacina.

Last Modified: 7/30/2014
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