The role of storage on Mancozeb fungicide formulations and their antifungal activity against Fusarium oxysporium and Rhizoctonia solani

The stability of fungicides Dicozeb 80% WP (Mancozeb), Sand flower 72% WP (Cymoxail + Mancozeb) and Triomax 66% WP (Cymoxail + Mancozeb + Copper oxychloride) were tested before and after storage at 54 ± 2 °C for 14 days and investigated their activity on radial growth of F. oxysporum and R. solani in vitro by Poisoned Food Technique. The results indicated that slightly increased of degradation rate of the active ingredient of Triomax followed by Sand flower and Dicozeb. The fungicidal activity of Mancozeb increased when mixed with Cymoxanil and Copper oxychloride by 97.4 and 73.4 times against F. oxysporum and R. solani, respectively. While Cymoxanil increased the activity of Mancozeb by 39.5 and 45.9 times against tested fungi F. oxysporum and R. solani, respectively. In addition, degradation of tested fungicides caused increase the mean activity of polyphenol oxidase enzyme and mean proline amino acid in mycelium of tested fungi. With another point of view, the present of Cymoxanil + Copper oxychloride in mixture of Triomax caused decrease in degradation of fungicidal activity of Mancozeb up on other tested fungicides.