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Ministdre de l'Agriculture du Canada, Saint-J ean et L' Assont ption, Qudbec-lRegu pour publication Ie 23 janvier, 19631 RESUME Contre Ia herrie, Plds-modiophora brassicae'Wor., des crucifdres le bichlorure de mercure fut Ie seul foneicide i permettre i la fois une auementation de rendement et une r6duction-de l'infection des racines du choul aussi bien en un sol min6ral qu'en un sol organique. Le Terraclor a 6t6 plus effcace en un sol min6ral ilors qu'en un-sol oreanique. ii fur inf6rieui au t6rnoin.Le Mylone a 6t6 l6gdremint plus efficaci en-un sol min6ral. L'Emmi et Ie Chemagro B-18,i3 ont I'un et I'autre diminu6 Ia r6colte en un sol min6ral, mais.l'infec.tion y fyr mieu.x r6primie qu'en un sol .organique. Ces deu-x rongrcldes lurent t_res pnytotoxrqucs, suftout en un sol mtneraL.

Eight turnip mosaic potyvirus (TuMV) isolates from the Campania region of Italy were characterized. Experiments based on host range and symptomatology indicated that the isolates were biologically different. In addition, the isolates, with the exception of ITA1 and ITA3, were distinguished from each other by using a combination of monoclonal antibodies recognizing the coat protein. Single-strand conformation polymorphism (SSCP) analysis of the coat protein gene revealed that each isolate produced a specific SSCP profile, except for isolates ITA1 and ITA3. This study indicates that (i) even in a small geographical region, there is a great deal of variation in TuMV isolates; (ii) the use of a set of four differential hosts does not always specify the same pathotype in different environments; (iii) the TuMV isolates with the same pathotype on Brassica napus test lines can still differ in host range, symptoms, serology, and SSCP; and (iv) there was perfect correlation between the panel of antibodies and SSCP in differentiating among the isolates; ITA1 and ITA3 were indistinguishable by either assay.

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