Fig. 5

Efficacy of potential defense inducers on leaves against grapevine downy mildew (P. viticola). Tests were carried out on a randomized block design with 4 blocks and 3 grapevine plants per block of Cabernet Sauvignon. Three modalities were studied: untreated, treated every week with 1Kg Ha-1 of active ingredient of BTH (Acibenzolar-S-methyl 50%, Bion® 50WG, Syngenta) and treated with 2.5 Kg Ha-1 of active ingredient of fosetyl aluminum (Fosetyl-Al 80%, Aliette®Flash, Bayer). Treatments were carried out between 3rd May and 19th July 2011 (12 treatments, T1 to T12 and red arrows) and with artificial inoculation performed on 19th May 2011 (green arrow). Disease severity was assessed 5 times between 9th June 2011 (after 5 treatments and 3 weeks after artificial inoculation) and 28th July by assessing the extent of attack on 30 leaves per block during the season. Leaves were sampled throughout the season: before any treatment to check the homogeneity of the parcel (S1), 48 h after the second treatment (S2), 48 h after the third treatment and just before artificial inoculation (S3), 48 h after artificial inoculation (S4), then later, 48 h after the seventh treatment (S5)