Potatoes are a staple crop in Egypt and around the world, contributing significantly to human nutrition. However, during handling, transportation, and storage, potato tubers are particularly vulnerable to a variety of fungal diseases. Two pathogenic aggressive isolates associated with potato tuber seeds (Solanum tuberosum L.) fungi namely Fusarium culmorum and Lasiodiplodia theobromae were obtained from the fungal collection established by the authors and tested in the present study. Their identification was confirmed based on cultural, morphological, and microscopic characteristics and molecular phylogenetic analysis. To control these isolates in Egypt, the research aims to determine the efficacy of some specific chemical fungicides, such as Moncut^®, Tazolen^®, and Divide^®, as well as the efficacy of biocontrol agents, such as Bio Zeid^®, Plant Guard^®, and Bio Arc^®, both in vitro and in vivo. All the tested fungicides and biocides significantly decreased the in vitro growth of F. culmorum and L. theobromae to different degrees. However, the highest colony growth inhibition was presented by fungicides Tazolen^® and bioagent Bio Zeid^®. Meanwhile, the results obtained under natural environmental conditions supported the in vitro results as the disease severity percentage was decreased, and reduction percentages were decreased due to using each of the tested treatments, but to varying degrees. It was evident that Bio Zeid^® was superior to all the other treatments and increased all plant parameters compared to untreated control.