Efficiency of resistance elicitors in the management of grapevine downy mildew Plasmopara viticola: epidemiological, biochemical and economic aspects Kedma Maria S. Pinto & Luciana Cordeiro do Nascimento & Erbs Cintra de Souza Gomes & Hilderlande Florêncio da Silva & Janaina dos Reis Miranda Accepted: 26 July 2012 / Published online: 21 September 2012 # KNPV 2012 Abstract 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 deter- mine their economic viability. The experiments were performed in a commercial vineyard variety ‘Isabel’ (Vitis labrusca) at Vale do Sirijí [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- Mos®, Fungicide+potassium phosphite, Fungicide +Agro-Mos®, potassium phosphite+AgroMós® and Fungicide+potassium phosphite+Agro-Mos®) 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 en- zymatic 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. Keywords Vitis labrusca L. . Mildew . Resistance induction Introduction Viticulture is a very important agricultural activity for both the social and the economic context worldwide. Italy and China are the two largest producers and Brazil ranks 15th among worldwide grape producers, with a production of 1,365,491 t in 2009 and exporting Eur J Plant Pathol (2012) 134:745–754 DOI 10.1007/s10658-012-0050-1 K. M. S. Pinto (*) : L. C. do Nascimento : J. dos Reis Miranda Programa de Pós-Graduação em Agronomia, Universidade Federal da Paraíba, CCA/UFPB, Campus II, Rodovia PB 079, Km 12, CEP 58397-000 Areia, PB, Brazil e-mail: kedma_maria@hotmail.com L. C. do Nascimento e-mail: luciana.cordeiro@cca.ufpb.br J. dos Reis Miranda e-mail: janaina-jua@hotmail.com E. C. de Souza Gomes Instituto Federal do Sertão Pernambucano, Petrolina, PE, Brazil e-mail: ectecnologo@hotmail.com H. F. da Silva Laboratório de Fitopatologia CCA/UFPB, Campus II, Rodovia PB 079, Km 12, CEP 58397-000 Areia, PB, Brazil e-mail: hildinhasilva@hotmail.com