Abstract

Abstract Background Apple root rot (ARR) is a typical soil-borne disease that seriously threatens the development of the apple industry. In this study, a biocontrol fungus named AT-1 was screened from the basal tissue of apple stem recovered from root rot infection, and it was identified as Trichoderma atroviride based on morphological characteristics and amplification of the ITS , LSU, and TEF 1 genes. Limited knowledge is present in using Trichoderma against ARR disease. Results In subsequent experiments, a potential biocontrol strain (AT-1) had significant antagonistic activity and easily parasitized a variety of ARR pathogens such as Rosellinia necatrix, Phytopythium vexans , and Athelia rolfsii. The lowest antifungal rate recorded was still more than 40%. In addition, different chemical fungicides were tested against pathogens and biocontrol strains. The control effect was 94.79% in May and 83.41% in August, when T. atroviride AT-1 was applied along with fungicides. Applying chemical fungicides brought more sensitivity against R. necatrix. Trichoderma strains had a good tolerance for azoxystrobin SC and difenoconazole WG fungicides. The antimicrobial strains effectively colonized in apple stem base for more than 1 month, produced many conidia, occupied a favorable niche, and finally, controlled the disease with more than 80% in the field. Conclusion Overall results suggested that T. atroviride AT-1 had a good potential in the prevention and control of ARR and had a good resistance against the applied fungicides, which can provide strain resources and a theoretical basis for ARR control.