Technical Abstract: Crop and soil management may modify canopy and belowground microclimate. However, their effects on potential development and control of early blight are not well documented. Crop management systems [Status Quo (SQ), Soil Conserving (SC), Soil Improving (SI), Disease Suppressive (DS), and Continuous Potato (PP)] were evaluated for their effects on early blight potential under irrigated and rainfed conditions. In 2006 and 2007, microclimatic data were recorded with a data logger deployed at the canopy level. Early blight was determined by visual assessment of symptoms and predictions from the Tom-Cast model. Early blight incidence and lesion numbers varied among cropping systems and between years. Disease incidence ranged from 31-64% (2006) and 12-43% (2007), and was significantly higher in PP compared to DS, SQ, SC, and SI systems. The relationships of Alternaria solani incidence and disease severity with microclimate varied and were mostly non-significant, suggesting that development of A. solani was not affected by microclimate. Early blight incidence was significantly associated with cropping systems. Prediction of early blight based on the Tom-Cast model was not correlated with observed disease levels. This research demonstrated that early blight disease is enhanced through continuous potato production.