Using some systemic resistance inducers to protect onion plants from Purple blotch disease


  • Agha M.K.M. Plant Pathology Unit, Plant Protection Dept., Desert Research Center, Cairo, Egypt.


Bacillus megaterium, Potassium, Phosphor, Pseudomonas fluorescens, Azotobacter chroococcum


Purple blotch caused by Alternaria porri (Ellis), Ciffen, causes serious problems in onion plants as a major limiting factor in onion cultivation where attacks older leaves and causes destructive damage to bulbs as well as seed crop. Fungicides application is the major way to manage this disease. But the use of fungicides has become a high cost to use, one of the obstacles to export due to the residual effect of fungicides, which causes the rejection of export shipments, in addition to the impact of the pollutant on the environment and humans. Therefore, it has become necessary to search for safe alternatives to fungicides to avoid the negative effects of fungicides. In this research, Plant systemic resistance inducers such as chemical, biological and mineral salts were used. Salicylic acid and Potassium Dibasic Phosphate as chemical inducers, while Bacillus megaterium, Pseudomonas fluorescens and Azotobacter chroococcum bacteria were used as bio-inducers. Sodium and Potassium bicarbonate mineral salts as well as Omega3 and Vetanool commercial compound to evaluate its effects in reducing the incidence and severity of Purple Blotch natural infection, enhancement vegetative growth, increasing the activity of oxidative enzymes (Peroxidase, Catalase), Potassium and Phosphor. All treatments that used significantly effected in decreasing Purple blotch incidence and severity in compared with fungicides and untreated control.