Efficiency of resistance elicitors in the management of grapevine downy mildew Plasmopara viticola: epidemiological, biochemical and economic aspects

This paper aimed to evaluate the efficiency of resistance elicitors in the management of grapevine downy mildew (Plasmopara viticola), identify the action of the elicitors on host metabolism, and determine their economic viability. The experiments were performed in a commercial vineyard variety 'Isabel' (Vitis labrusca) at Vale do Siriji [Natuba, Paraiba State in Brazil, in the period of September 2009 to January 2010 (first season) and February to June 2010 (second season)]. The statistical design of randomized blocks consisted of eight treatments (untreated control, fungicide (pyraclostrobin+metiram), potassium phosphite, Agro-MosA (R), Fungicide+potassium phosphite, Fungicide+Agro-MosA (R), potassium phosphite+AgroMsA (R) and Fungicide+potassium phosphite+Agro-MosA (R)) with four replications, with the experimental unit consisting of 45 leaves. Applications were made every 7 days, starting 20 days after pruning (DAP) with a total of 12 sprays. The evaluations were carried out biweekly, analyzing the following variables: incubation period, disease incidence and severity, area under the disease progress curve, and efficiency of control. The enzymatic determination was performed using pulp extracts from three fruits harvested at 45, 60, 90 and 120 DAP for each treatment. The resistance elicitors were able to reduce the disease incidence under different climatic conditions, indicating their viability as an alternative for the management of Plasmopara viticola.