Management of Rose Powdery Mildew by Nanosilica, Diatomite and Bentocide

Recent trends in integrated pest management suggest that certain natural fungicides have positive effects on plant growth and disease management. This study was conducted to evaluate the possibility of using nanosilica, diatomite and bentocide instead of commercial fungicides against powdery mildew of rose. Silica nanoparticles and diatomite were applied at various concentrations to study the antifungal activity of each concentration. Application with either nanosilica at 500 mg/l water, bentocide at 2500 mg/l water, the fungicide (Penconazole) at 0.25 ml/l water or diatomite at 3000 mg/l showed significant reductions in disease severity comparing with the other treatments. Other treatments, nanosilica at 125 and 250 mg/l water and diatomite at 1000 and 2000 mg/l water, recorded moderate reduction in disease severity. Microscopic observations revealed that silica nanoparticles caused damage effects on fungal structures of the pathogen. Based on RT-PCR, rose plants treated with nanosilica, bentocide and diatomite exhibited increased expression of phenylalanine ammonia lyase (PAL) gene.