Evaluation of the Efficacy of CGA 245704 Combined or Not with CGA 329 351 (Mefenoxam) for the Control of Tobacco Blue Mold (Peronospora Tabacina): Results of Four Years of Experiments

A compound for activating systemic resistance (CGA 245 704), in the chemical class of benzothiadiazoles, was studied since 1993 for the control of tobacco blue mold (Peronosporatabacina A.) in seedbeds and in the field. One foliar application of CGA 245 704 at 1.6 g active ingredient/hl every 14 days protected tobacco plants against blue mold but protection was not total. Mixed with mefenoxam (CGA 329 351) at 16 g active ingredient/hl the protection is equivalent to standard Acylon¯ TC (25 % metalaxyl, 50 % maneb) applied as foliar spray at 0.160 kg/hl (40 g active ingredient metalaxyl per hl). This allows a reduction in the quantity of fungicides dispersed in the environment and the pesticide residues on the tobacco leaves. At the rate applied, no phytotoxic effects were observed in seedbeds or in the field.