Association among weather parameters and incidence of downy mildew in grapes

Disease incidence was reflected collectively by preceding week's ecological variables viz., Minimum temperature (X1), Maximum temperature (X2), Relative humidity at 07.30 hours (X3) and at 13.30 hours (X4), Evaporation (X5), Amount of rainfall (X7) and Wind speed (X6). Correlation analysis showed that Relative humidity at 07.30 and 13.30 hrs had positive correlation with percent disease incidence of downy mildew on grapes while vapour pressure deficit had negative relationship for backward and fore pruning data sets.