Grapes have the potential for continuous production after a short rest period between seasons, but climate risks may limit this practice. The objective of this study was to evaluate the climatic potential for two harvests of grapes per year and to estimate the severity of downy mildew, according to different pruning times and thermal requirements (degree-days) for grape genotypes (Vitis spp.), in the State of Parana, Brazil. Frost risk, normal climatological water balance and potential severity of downy mildew were evaluated using data from 21 meteorological stations of the Instituto Agronômico do Paraná. The occurrence of frost limits the growing season of grapevines in the central, south and east regions of the state. The water excess is observed throughout the state. Genotypes with requirements from 1,800°C day between pruning and harvesting can only be cultivated in double annual crop in the warmer areas of the State. It is not possible to obtain two harvests per year when using grapevine genotypes that require more than 2,000°C day. In colder areas, only genotypes with requirements between 1,000 and 1,200°C day may be used. Due to the potential severity of downy mildew in the State, American grapes are indicated for the center, south and east areas, while European grapes are indicated for the southwest, west, north and northwest areas. The grape cultivation in those areas does not discard the need of disease chemical control during the most susceptible phenological phases.
climatic risk; Vitis; degree-days; downy mildew
