Trichoderma atroviride isolated from diseased apple stem have possible biocontrol effect and tolerance toward azoxystrobin and difenoconazole

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.