1 the PVY Collaborative Experiment 1996-2002: a Global Synthesis
The PVY collaborative experiment 1996-2002: a global synthesis of results. VERRIER, Jean-Loui s (*), DOROSZEWSKA, Teresa (**). (*)ALTADIS- Institut du tabac, Bergerac, France. (**) Institute of Soil Science and Plant Cultivation, Pulawy, Poland. Summary. A synthesis based on observations accumulated since the start of this collaborative work, which involved 151 trials in 27 countries between 1996 and 2002, highlights the following results: • assessment of different PVY resistance sources in N. tabacum , with regard to the global frequency of breakage of these resistances, • world distribution, frequency and trends of the tobacco disease caused by necrotic PVY strains. Results are discussed by referring to knowledge’s concerning the PVY disease, namely: • consequences of the PVY disease on the tobacco leaf chemical equilibrium, • understanding of the resistance mechanism conferred by the « va » gene, • possibilities of control through breeding, • other possibilities of control. Application of this knowledge in the view of GAP programs is considered. New trends of the collaborative experiment are proposed. Introduction. Among tobacco pathogens, Potato Virus Y is the most widespread, occurring in every tobacco producing country (5, 10). PVY infection affects yield and leaf quality. The cured leaf chemical balance is modified, with a greater importance of total nitrogen, which has been shown to be associated with an increased smoke mutagenicity (36). Since PVY is transmitted by aphids upon the non-persistent mode, the use of insecticides to eliminate aphids has a low efficiency for controlling the virus. Other methods to prevent virus transmission by aphids have been proposed, and have been found efficient to some extent in the case of PVY in tobacco (6, 19).
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