In this study, we examine whether the adoption of late blight resistant cultivars has an effect on yields and fungicide use. We will focus on the Amarilis variety which is considered more resistant to late blight than other varieties adopted by the farmers in the sample. Using data from three main potato producer states in the Peruvian Andes, significant positive effects on yields and negative effects on fungicide use are found. Specifically, the damage abatement approach provides evidence that Amarilis adoption enhances output maximization mainly through the control of late blight. At the discount rate of 10%, the probable net present value (NPV) of the net benefits accruing to farmers through the adoption of Amarilis amounts to almost 9 million dollars.