Efficacy of Acibenzolar-S-Methyl Against Wildfire Blight (Pseudomonas syringae pv. tabaci tox+) of Paprika (Capsicum annuum L.) Seedlings

Wildfire leaf spot caused by Psuedomonas syringae pv. tabaci + is a important seedbed diseases of Solanaceous crops in Zimbabwe. It results in loses of economic significance in yield quality every season. The objective of this study was to evaluate the efficacy of Acibenzolar-S-methyl (ABM; Actigard 50 WP, Syngenta Inc.) against Wildfire (Pseudomonas syringae pv. tabaci+) in paprika seedlings. ABM was evaluated for its ability to suppress Pseudomonas syringae pv. tabaci tox + of paprika (Capsicum anuum L.) seedlings in the greenhouse. Four ABM spraying treatments differing in concentration and application intervals were evaluated and compared with the standard practice of spraying copper oxychloride at a rate of 1.56 g ai m-2. Paprika seedlings sprayed with ABM were significantly protected from wildfire (Pseudomonas syringae pv. tabaci tox +). The ABM restricted the incidence and severity of wildfire pathogens from progressing within leaf lamina as shown by a lower Area Under Disease Progress Curve (AUDPC) for disease incidence in seedlings sprayed with ABM when compared to seedlings sprayed with copper oxychloride. Since, both levels of the active ingredient confer resistance exhibiting no significant differences in severity and incidence of wildfire, it is therefore more economic to apply lower rates at lower frequencies in the nursery. The ABM may be a useful tool in IPM programs or replacement of pesticide such as copper oxychloride in the management of Pseudomonas syringae pv. tabaci tox +.