Effect of some fungicides alternatives on reducing disease severity of Stemphylium Blight in onion

Abstract

Onion production suffered from decreasing in productivity due to some fungal diseases during growing season. One of the most destructive diseases exposed onion is Stemphylium leaf blight (SLB) caused by the fungus Stemphylium vesicarium (Wallr.) Simmons, (teleomorph: Pleospora allii. (Rabenh.) Ces. and de Not). It had wide host range and wide range of variability in disease symptoms expression depending on cultivars, environmental conditions etc., now a days the high cost of using fungicides and fungal strains that are resistant to the effect of fungicides, which were formed as a result of the excessive use of pesticides and the environmental pollution associated with the use of pesticides, Among the alternatives of fungicides are the inducers of plant systemic acquired resistance (SAR) and mineral salts. In this work, the effect of Salicylic acid (SA), Potassium phosphate dibasic (PD) as inducers for (SAR),
Sodium bicarbonate (SBC), Potassium carbonate (PC), Sodium carbonate (SC) salts was studied on reducing the incidence and severity of natural infection of SLB with improving vegetative growth of onion. The results showed that (SA) followed by (PD) gave significant differences in reducing both of natural disease incidence and disease severity for Stemphylium leaf blight, and increasing vegetative
growth of onion in comparison with control, also both SA and PD increased activity of peroxidase and catalase enzymes in treated plants. All used salts (SBC, PC, and SC) significantly reduced both disease incidence and disease severity, increasing vegetative growth of onion plants and increase enzymes activity in comparison with control. So it can concluded that using the above treatments will be
economic and ecofriendly alternatives in Stemphylium blight disease management.