A suitable alternative to antifungal agents for the control of early blight disease-Alternaria alternata of tomato

Abstract

Early blight (EB), caused by the dominant species Alternaria alternata, is a major global disease of tomato (Solanum lycopersicum L.; Solanaceae) reducing the vegetative organs and causing losses. Sustainable food production mainly depends on the rational use of chemical fertilizers and fungicides in integrated plant disease management. Hence, the fungicidal activity of ortivatop^® (azoxystrobin + difenoconazole), Signum WG 33.4% (pyraclostrobin + boscalid) and daconyl SC 72% (chlorothalonyl) was evaluated against tomato EB disease under field conditions. Two experiments were conducted during the cropping seasons from 2019 to 2020 in three regions. The experimental design was a randomized block with 4 replications using Ortivatop^® (ORT) at three doses of -900, -1100 and -1300 ml. ha⁻¹ (recommended doses of the company), daconyl (DAC) 2 l. ha⁻¹ and Signum (SIG) 0.5 l. ha⁻¹. The findings showed that ORT-1300 (20.6%) and DAC (22.7%) resulted in the lowest EB disease severity, followed by SIG (25.7%), ORT-1100 (26.9%) and ORT-900 (31.7), in contrast to 59.1% of the control. Compared with treatment without fungicide, all fungicides reduced the AUDPC (area under disease progress curve) and provided an increase in productivity. ORT-1300 ml ha⁻¹ showed the greatest reduction in AUDPC by up to 70% and increased tomato yield by threefold more than the untreated control. Therefore, the current study suggests that foliar spraying with ORT-1300 ml. ha⁻¹ at all three growth stages, is an ideal solution for EB disease management.