This document provides information on diseases that affect tomatoes, including early blight, late blight, and other bacterial and viral diseases. Early blight is caused by Alternaria solani and presents as dark brown spots on leaves and stems. Late blight is caused by Phytophthora infestans and results in large, dark brown leaf blotches and spots on fruits and stems. Management of these diseases involves cultural controls like removing debris, improving airflow, and rotating crops, as well as applying fungicides in a preventative manner.