ارزیابی تاثیر غلظتهای مختلف قارچ کش (200) Miravis Duo 75C در کنترل بیماری سفیدک پودری گوجه فرنگی در شرایط مزرعه ای.

The present study aimed to find out the minimum effective concentration of Miravis Duo®75 (SC 200) fungicide for preventing the progress of tomato powdery mildew disease caused by Leveillula taurica, in comparison with Signum® fungicide under field conditions. Two experiments were performed in Karaj and Mashad using Randomized Complete Block Design (RCBD) with five treatments and four replications. Treatments were three concentarions of Miravis Duo® (700, 1000 and 1200 ml/ha), Signum® (500 g/ha) as reference fungicide and water spraying as the control. Foliar spraying of experimental plots was started as the first disease symptoms appeared and repeated four times at 11 days intervals. The effect of treatments was assessed before each spraying by estimating the percentage of plant foliage covered by powdery mildew for five randomly selected plants in each replication. Analysis of variance of data in both locations showed that the effect of treatments on disease severity index (DSI) and the Area Under Disease Progress Curve (AUDPC) were significantly different (P≤ 0.01). Also in both locations, there were significant differences between 700 ml/ha of Miravis Duo® and the other two Miravis Duo® concentrations of this fungicide (1000 and 1200 ml/ha) as well as Signum® fungicide, in reducing DSI, although there were not statistically significant difference between 1000 and 1200 ml/ha concentrations. The efficiency of 1000 and 1200 ml/ha concentrations were 59% and 65.5% respectively compared to the control, which were not significantly different with Signum®. Therefore the minimum effective dose of Miravis Duo ® fungicide for controling tomato powdery mildew is 1000 ml/ha which recommended alternatively with other registered fungicides. [ABSTRACT FROM AUTHOR]