Biological control of bean Fusarium wilt by silver nanoparticle extract of Trichoderma harzianum

Fusarium wilt caused by Fusarium oxysporum f.sp. phaseoli is an important worldwide disease of beans. The pathogenicity of two isolates from the southwest of Iran was tested on cowpea, red bean, and kidney bean. To find the appropriate method for biological control of the disease, the inhibition of mycelial growth of fungal isolates by silver nanoparticle extract of Trichoderma harzianum was investigated in vitro. The extract of superior isolate of T. harzianum was converted into nanoparticles by mixing with silver-nitrate solution, and the formation of nanoparticles was proved by ultraviolet light spectroscopy. The maximum absorption was at 440 nm in a concentration of 5 Mm of silver-nitrate. The inhibitory effect of 10 concentrations of this nanoparticle on the mycelial growth of hyper-virulent isolate of the pathogen examined and the concentration of EC50 = 650 ppm was determined. The effect of EC30, EC50, EC70 concentrations of this synthesized nanoparticles solution, pure T. harzianum extract and silver-nitrate solution on the severity of the disease in kidney and red beans was tested in greenhouse conditions. All treatments significantly reduced the severity of the disease in beans, but their efficacy was lower than those of silver-nitrate and pure extract of T. harzianum. The biological control potential of Fusarium wilt by silver nanoparticle extract of T. harzianum is being reported for the first time.