Tomatoes are the second most produced vegetable in the world with a global trade value of 10.3 billion dollars in 2021. While these valuable vegetables are commonly grown, they are known to suffer from a highly destructive physiological disorder called Blossom End Rot (BER). BER is a highly environmentally dependent physiological disorder that causes a black leathery lesion to form on the distal end of the fruit in multiple species including pepper, eggplant, and watermelon. In tomatoes up to 41 percent of tomatoes lost in greenhouse production are lost due to BER. Finding a mode of resistance to this disorder would lead to more sustainable and profitable tomato production. Due to the importance of this resistance, several BER quantitative trait loci (QTL) have been mapped including BER3.1, BER3.2, BER4.1, and BER11. Through work in the Van der Knaap Lab BER4.1 was fine mapped to a region containing two genes related to reactive oxygen species (ROS) detoxification and one related to sugar transport. To analyze the potential differences in ROS between resistant and susceptible plants an oxidative stress experiment was designed. Following this experiment another BER QTL, BER11.1, was confirmed and more genes of interest were identified. The goal of this research was to expand the scientific knowledge of BER and utilize this knowledge for future breeding efforts.