Management of Turcicum Leaf Blight (Exserohilum turcicum) of Maize (Zea mays) through Evaluation of Maize Varieties and Fungicide Spray Frequencies at Ambo, Ethiopia

Abstract

Article InfoTurcicum 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.

Epidemic development and management of common leaf rust (Puccinia sorghi Schwein) and turcicum leaf blight [Exserohilum turcicum (Pass.)] of maize (Zea mays L.) in eastern Ethiopia

“…In addition to periodic changes in the weather, changes in the host-pathogen genetic interrelationship may also be induced by the introduction of new cultivars or the occurrence of mutations and recombination in the pathogen, which influences the epidemic development of the diseases. Tajudin et al (2018) reported that the TLB progression rate ranged between 0.016 and 0.093 unit day −1 . Additionally, Megersa et al (2017) reported that the highest TLB progression rate was recorded in the variety BH-543 (0.041 unit day −1 ).…”

“…Tajudin et al. (2018) indicated that TLB on maize reduced the NEPP, ear size (length), and NRPE, while checking TLB development with propiconazole, especially with three application frequencies, significantly increased these yield parameters. A significant increase in plant height was noticed in fungicide‐protected plots over unprotected plots.…”

“…(2017) reported that TLB incidence on maize resulted in a 40.7% yield reduction. For susceptible cultivars, such as AMHQ‐760, relative yield losses as high as 62.42% have been recorded for maize (Tajudin et al., 2018). TLB is an important disease that affects photosynthesis with a severe reduction in grain yield of 28%–91% (Bindhu et al., 2017).…”

“…Tajudin et al. (2018) reported that the TLB progression rate ranged between 0.016 and 0.093 unit day −1 . Additionally, Megersa et al.…”

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