Purpose: Evaluation of efficacy of Talaromyces flavus microcapsule in controlling cotton important fungal diseases and introducing Talaromyces flavus for using in the cotton fields. Methods: In this research focused on the application and efficiency evaluation of two new formulations of T. flavus microcapsules (TF-Co-G-1: Isolate 1 obtained from the Gorgan cotton farm) in suspension and powder forms, which were compared with the fungicide Talaromin® in farmers' fields. In this research, two cotton farms (Karkandeh and Hashemabad) with a history of infection with VW and DO were selected in two different regions of Golestan province. Each of the fields with an area of 1000 m2 was divided into seven equal parts. In each part, the treatments were applied separately, including microcapsule suspension with soil application, microcapsule suspension as seed impregnation, microcapsule powder with soil application, microcapsule suspension as seed impregnation, Talaromin® fungicide with soil application, Talaromin® as seed impregnation, and a control. The efficiencies of different treatments in terms of controlling the studied diseases and strengthening different growth indicators were evaluated by comparing the means of nine measured traits, including three traits for disease indicators (the percentage healthy seedlings for DO and the incidence rate and severity percentage of VW). To this end, the mixed analysis of variance (ANOVA) was first performed for two regions using the MS TAT C software, and the ANOVA of means was performed for each region separately with the significant effect of treatment × location. Results and conclusion: The results showed that among the studied formulations, powder microcapsules with seed impregnation by 32% and Talaromin® with soil application by 59% were respectively the most effective treatments for a significant increase in the percentage of healthy seedlings and a significant decrease in the severity of VW. Therefore, the obtained results indicate that the technical knowledge to produce T. flavus microcapsule formulations with two forms of suspension and powder can be transferred to manufacturing companies to carry out the commercialization and mass production process. Originality/value: Production of Talaromyces flavus microcapsule.