Study on the Effect of metalaxyl- mancozeb (WP 72%) in the Control of Cucumber Damping-off Disease (Phytophthora drechsleri Tuckers) in Field and Glasshouse Cultures

Efficacy of metalaxyl-mancozeb (Rosalaxyl® WP 72%) in controlling of cucumber damping off disease agent (Phytophthora drechsleri) was studied under field and glasshouse conditions. Treatments were different doses of Rosalaxyl as the new and metalaxyl (Ridomil® G 5%) as the reference fungicide. Field trials were done in micro plots at Complete Randomized Design with 4 treatments and 4 replications as soil drench system. Glasshouse trials were done at Complete Randomized Block Design with 5 treatments and 4 replications at three continuous sequences as soil drench, soil incorporation and combination of the two methods. Trials were done during the years 2012-13 in Karaj. Evaluation of treatments was carried out by the determination of the percentage of infected plants in the period from emergence to 4-leaf stage. The results of the field trials show that Rosalaxyl WP 72% at the rates of 0.2% and 0.3% and Ridomil G 5% at the rate of 0.2% have the same effects and decreased the occurrence of the disease by 74%, 74.67% and 67% respectively compared to the control treatment. The results of the glasshouse trials show that in “Soil Incorporation” application method, Rosalaxyl at the rate of 300 g/m3 of soil decreased the disease rate by 63.51% with the “Soil Drench System” application method, Rosalaxyl at the rate of 0.3% by 74.50% and in the integration of the two application systems, at the rate of 300 g/m3 of soil as soil incorporation method and at the rate of 0.3% as soil drench method along with the irrigation water at 2-leaf stage with 87.11% had the best effects in controlling of cucumber Damping-off disease compared with the control. Based on the present results, Rosalaxyl is recommended to be applied at the rate of 0.2% to control Damping-off disease of cucumber both in field and nurseries as soil drench system. Meanwhile, as a component of integrated control method in glasshouse, the application of Rosalaxyl at the rate of 300 g/m3 as pre-sowing by soil incorporation method and at the rate of 0.2% in the 2 leaf stage by soil drench method is recommended.