Influence of planting date on incidence and severity of viral disease on cucurbits under field condition

Three field experiments were conducted to assess the effect of planting date on the incidence of viral diseases and the severity and the susceptibility of the cultivars. Two cultivars of cucumber (Hybrid Tokyo F1 and Poinsett) and one local variety of zucchini (Bolle) were used for the evaluation in May-July 2014, September-November 2014, and February-April 2015. A randomized complete block design with three replications was used for the experiments. Data were collected on disease incidence, severity, and time until first symptoms occurred. Area under severity index progress curve (AUSIPC) and area under disease progress curve (AUDPC) were calculated respectively for disease severity as well as the incidence on each cultivar. The results demonstrate the susceptibility of all cultivars to the tested viral diseases. The effect of planting dates on cultivars was significantly different (P < 0.05) at the different growing stages whereas there was no significant difference (P > 0.05) in planting date-variety interaction.