The present invention describes substantially pure cultures of three new species of fungi, Meira geulakonigae (CBS 110052), Meira argovae (CBS 110053) and Acaromyces ingoldii (CBS 110050) (all nom. prov.), wherein said cultures are biologically pure. The conditioned medium for all three new fungi species is also described, as well as their biologically active products. The biological product of the three new fungi species and their conditioned medium has miticidal and fungicidal activities. Thus, a composition for the control of mites and/or phytopathogenic fungi comprising a biocontrol agent derived from any one of the three new fungi species is also described, optionally comprising an agriculturally compatible carrier. Finally, the present invention describes a method for producing a fungicide and/or a miticide, wherein the active ingredient of said fungicide/miticide is any one of M. geulakonigae, M. argovae, or A. ingoldii, or any combination thereof, and/or a culture thereof, and/or any product or derivative thereof, comprising culturing said fungus and optionally isolating said active ingredient from the culture.