Evaluation of Fungicides against Downy Mildew (Peronospora destructor Berk) of Onion (Allium cepa) in Bale Zone, South Eastern Ethiopia

Aims: To evaluate the efficacy of tested fungicides against downy mildew of onion and determine the appropriate interval of fungicides application.

Study Design: The experiment was laid out down in randomized complete block design with three replications for each treatments.

Place and Duration of Study: The experiment was carried out in farmers field of Aloshe village; Goba district of Bale zone in 2018/2019 during “Bona Season”.

Methodology: Locally available onion variety and two tested fungicides (Mancozeb (Mancozeb 80 Wp) and Ridomil (Ridomil Gold MZ 68WG) were used. Locally available variety of onion was planted in a plot size of 3m x 2.4m with three replications. Each two fungicides were applied at interval of seven day, fourteen and twenty one day interval including unapplied fungicide plot as control.

Results: The result indicated that, both fungicides (Mancozeb and Ridomil) were effectively reduces the severity level of the disease. The higher plant height(42.5cm), bulb weigh (289g), total weight of the bulbs (114Qt/ha) and lower severity (8.35%) were recorded from weekly application of Ridomil, fourteen day application of Ridomil and weekly application interval of Mancozeb. The higher marginal rate of return of 2833.45% and 1999.07% were recorded from weekly and fourteen applications of Mancozeb and Ridomil respectively.

Conclusion: The minimum application frequency of three times of Ridomil in fourteen days and weekly interval application of Mancozeb were effective against downy mildew and profitable.