Foliar diseases are the significant production constraints in tomatoes. Among them, foliar fungal diseases in tomatoes, such as early blight (Alternaria linaria), Septoria leaf spot (Septoria lycopersici), and late blight (Phytophthora infestans), which is oomycetes, have higher economic significance. This paper will discuss the etiology, host range, distribution, symptoms, and disease cycle to help us understand the biology, followed by management approaches emphasizing the resistance breeding approach for these diseases. We provide an analytical review of crop improvement efforts, including conventional and molecular methods for improving these diseases’ resistance. We discuss the importance of modern breeding tools, including genomics, genetic transformation, and genome editing, to improve the resistance to these diseases in the future.