Abstract            Volume:6  Issue-8  Year-2018         Original Research Articles

Online ISSN : 2347 - 3215 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcret@gmail.com

Turcicum leaf blight (Exserohilum turcicum), TLB, is a major disease affecting maize (Zea mays) in western Ethiopia. The aims of this study wereto: evaluate maize varieties and propiconazole spray frequencies on epidemics of TLB, determine optimum propiconazole (tilt 250 EC) spray frequency for integrated management of TLB, and assess the cost/benefit of using propiconazole for each spray frequency against TLB. The effects of maize varieties, fungicide frequencies and their interactions on TLB development were assessed in a field experiment during the 2017 main growing season at Ambo Plant Protection Research Centre (APPRC). The experiment involved three maize varieties(AMHQ-760,Wonchi and Jibat) and three fungicide (Tilt, propiconazole) frequencies arranged in a factorial setting in randomized complete block design with three replications. One unsprayed check for each hybrid varieties was included. TLB was initiated following artificial inoculation. Data were recorded on disease incidence and severity. Six time severity scores were used to calculate area under disease progress curve (AUDPC) and infection rate. Grain yield and yield components weremeasured after harvest. Finally correlation and economic analyses were carried out. Disease parameters varied markedly acrosstreatments, especially variety-fungicide combinations had a highly significant variation (p<0.01) in disease parameters. The highest terminal percent severity index (PSI) (86.7%), AUDPC value (2614.4 %-day) and disease progress rate (0.09339 units-day-1) were recorded on unsprayed variety AMHQ-760. On the other hand, the same variety had significantly lower disease level and gave the highest grain yield (9.424 t ha-1) when it was treated thrice with propiconazole. TLB resulted in grain yield losses of up to 62.4% on AMHQ-760. PSI, AUDPC, incidence and disease progress rate were negatively correlated with yield and yield components. The highest marginal benefit (ETB 63,089 ha-1), and marginal rate of return (ETB 14.53) were obtained from variety AMHQ-760 with thrice application of propiconazole. Based on current results, thrice propiconazoles pray were found effective to manage TLB even on susceptible maize variety. However, additional experiments should be carried out to verify the current results.

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