Bull. Spec. CORESTA Congress, Yokohama, 1996, p. 169, P18

Evaluation of five fungicides and three application methods in the control of Peronospora tabacina

Istituto Sperimentale per il Tabacco, Scafati, Italy
A trial with 10 treatments and three replications with RCB design was made with the aim to reduce the use of chemical and to compare five fungicides: a) Fosetyl Al 32.5% + Cymoxanil 2.5% + Mancozeb 25%; b) Anilazine 50% + Cymoxanil 4.8%; c) Mancozeb 75%; d) RPA 407213 70%; e) RPA 407213 + Fosetyl Al 80%, with scheduled applications against P. tabacina . RPA 407213 is an experimental imidazolic fungicide with no systemic behaviour. To reduce level applications, two of these fungicides, (Fosetyl Al 32.5% + Cymoxanil 2.5% + Mancozeb 25% and Anilazine 50% + Cymoxanil 4.8%), were also used with three different application methods: 1) 4 scheduled applications; 2) the first application at the outbreak of symptoms and then two applications every 12 days; 3) as treatment 2, but the second application was made at the appearance of new spots at least on one leaf in the plot and the third application after 12 days. All fungicides tested with scheduled applications gave good control of P. tabacina with best performances for RPA 407213 with 5 applications with 8 days interval and RPA 407213 + Fosetyl Al 80%, with 4 applications with 12 days interval. P. tabacina was controlled with three applications using systemic fungicides and monitoring the crop in order to observe the outbreak of the symptoms. In our trial we had good control for all treatments and less control in the plot with Anilazine 50% + Cymoxanil 4.8% applied as in treatment 2. In the case of low infection level and slow development of epidemics it is possible to reduce chemical applications, monitoring the field and applying fungicides in correspondence of the outbreak of the symptoms; the control of the development of new spots after the first application has showed interesting possibilities to further reduce the use of fungicides.