Efficacy of four fungicides and their mixtures with two antioxidants on Alternaria solani fungus under laboratory conditions

Early blight disease (EBD) caused by Alternaria solani fungus is one of the most important diseases infecting potato and tomato plants in Egypt and other countries of the world. This disease caused great losses on production of many crops. The main goal of this study is to evaluate additions of two antioxidants (ascorbic acid and salicylic acid) at 5, 10 and 50 ppm to four fungicides (at IC50 value) on mycelial growth of A. solani fungus under laboratory conditions. Also, the effects on the vital ingredients such as fresh weight, total carbohydrates, total lipids and total protein were recorded. The results clearly indicated that, the increasing of concentrations from 5 to 50 ppm increased the fungitoxicity of azoxystrobin difenoxonazole, kresoxim-methyl and tebuconazole on A. solani and mixtures with salicylic acid were more effective than mixtures with ascorbic acid. Difenoconazole and tebuconazole were more effective than azoxystrobin and the least effective was kresokim-methyl, respectively. They concluded that the mixing of salicylic acid with four fungicides may be reduced the rate of applications of these fungicides in the field and reduce fungicides in the environment. They added that we need the researches in the fields to support these data under nature conditions.