Cereal, including barley, wheat, and oats, is a major winter food crop in Korea. Despite recent changes in agricultural environments in response to climate change, fungal diseases that could affect cereal productivity remain poorly understood. In this study, we investigated the incidence of diseases in barley, wheat, and oats in the southern part of Korea. We collected fungal pathogens from seven locations where cereals were grown. In March-April of 2020 and 2021, a total of 92 fungal isolates were collected, mainly from the stem base or leaves of cereal crops during the tillering and stem extension stages of cereals in Korea. The collected isolates were identified based on morphological and molecular biological characteristics. The dominant species was <i>Ceratobasidium cereale</i> (42.4%), followed by <i>Pyrenophora teres</i> (21.7%), <i>P. avenae</i> (10.9%), <i>Alternaria alternata</i> (6.5%), and <i>Epicoccum tobaicum</i> (6.5%). In addition, <i>P. tritici-repentis</i> (3.3%), <i>Cladosporium</i> sp. (3.3%), <i>Fusarium</i> sp. (3.3%), and <i>Nigrospora</i> sp. (2.2%) were also collected as minority groups. Our results will provide information on fungal pathogens that occur during the growing season of cereals in Korea, particularly during the tillering and stem extension stages. In addition, the isolates collected from this study can serve as a valuable resource for conducting simulations on climate change, focusing on temperature and humidity.