Sensitivity of isolates of Plasmopara viticola to strobilurins in the State of São Paulo and their relationship to downy mildew management

• Grant number: 17/07782-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2017
• End date: May 31, 2018
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Principal Investigator: Lilian Amorim
• Grantee: Larissa Helena Visioli
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 13/24003-9 - Grape diseases: epidemiology, damage assessment and control, AP.TEM

Abstract

The viticulture in the State of São Paulo represents 14% of the Brazilian production. One of the major problems in São Paulo viticulture is the frequent occurrence of downy mildew (Plasmopara viticola). The average number of fungicide spraying in São Paulo vineyards is in average 103 and 59 in European and American grapevine cultivares, respectively. Most of these sprays aim to control downy mildew. This type of management may select isolates of the pathogen resistant to fungicides and, as a consequence, may lead to an inefficient control of the disease. This proposal is part of a Thematic Project whose objective is to reduce the use of fungicides in grapevine. This project intends (I) to evaluate the sensitivity of isolates of Plasmopara viticola to pyraclostrobin, a fungicide of the strobilurin group, (II) to characterize molecularly the resistant isolates, and (III) to relate the occurrence of fungicide resistance to the management performed by growers of 'Niagara Rosada' in the State of São Paulo. To achieve these objectives, the sensitivity of Plasmopara viticola isolates collected in different regions of the State of São Paulo will be tested in vivo. The presence of mutations related to strobilurin resistance will be verified and the frequency of resistant isolates will be related to the fungicide management used at the vineyards in which the isolates will be collected. (AU)