A Higher Total Yield Was Recorded from Sewage Irrigated Field Than the Control Field. the Increase In Infection on Pods Correspondingly Decreased With Its Progress of the Pod Length, Number of Seeds Per Pod, 1000 Seed Weight and the Percent Oil Contents of the Seeds. the Diseases Were Also Responsible For Loses In Yield Production. Both the Fields Showed Only Two Diseases of Fungal Pathogens I.E. Alternaria Blight and White Rust of Mustard. Both the Diseases Were Found to Cause a Great Loss In Total Production of the Crop. the Correlation Coefficient Was Negatively Significant, Showing Inverse Association of Two Characters Indicating That Increase In Per Cent Incidence of Disease the Yield Decreased. Leaf and Pod Infection Also Represented a Negative Correlation With the Seed Yield. the Regression Study Revealed That Due to One Per Cent Leaf Infection the Yield Decreased 24.56 Kg Per Hectare. the Losses In Yield Were Estimated Upto 74.92 Per Cent With 46.06 Per Cent Disease Incidence In Tubewell Irrigated Field and 70.52 Per Cent With 43.86 Per Cent Disease In Sewage Irrigated Field. a Highly Significant Variation In Per Cent Disease Index Due to Crop Growth Stages and Due to Field Types Was Proved Statistically. an Assessment of Yield Loss By Comparative Determination Revealed That With the Increase of Infection on Pods, the Pod Length, Number of Seeds Per Pod, Seed Weight and Oil Per Cent Decreased Progressively and the Number of Infected Seeds Increased With the Increase O ...