DISTRIBUTION AND INTEGRATED MANAGEMENT OF COMMON LEAF RUST (Puccinia sorghi Schwein) AND TURCICUM LEAF BLIGHT (Exserohilum turcicum (PASS.) OF MAIZE (Zea mays L.) IN HARARGHE HIGHLANDS, EASTERN ETHIOPIA

Abstract

Maize (Zea mays L.) is the most produced creal crop in the world. Specifically, in Ethiopia more land is being used for (small-scale) maize production to meet future food demands. Common leaf rust (CLR) and Turcicum leaf blight (TLB) are the key foliar diseases that hampers maize production in Ethiopia. However, in the Eastern Ethiopia, Hararghe information related to the distribution, abundance of CLR and TLB and relation of diseases with independent factors which are essential for making management decisions concerning is lacking. Therefore, This study was initiated with the objectives of assessing the prevalence of CLR and TLB, weaknesses in management and formulate appropriate recommendation of fungicide. A survey was conducted in 2019 cropping season in different agro-ecological Zones of East and West Hararghe For each field assessed,disease incidence, severity, altitude (m), type of cropping system (intercropping versus sole cropping), crop combination, preceding crop and weeding were recorded. Data was analysis was done by using the SAS procedures GENMOD. Common leaf rust disease incidence range 16.84 to 100% obtained from Kombolcha and Kunii district, respectively. The severity was 6.0% from Kombolcha and 58.2 from Kunii and Cheleko. Although, TLB disease incidence ranged to 13.4 to 100% from kobo and Haramaya district, respectively. The severity was 6.0 and 58.0 % from Kombolcha and Kunii district, respectively. High CLR disease incidence and severity (> 61.7% and >32.1%) respectively, and High TLB disease incidence and severity (> 58.1% and >30.2%) respectively, was highly associated with west Hararghe Zone, Altitude >2000 m.a.s.l., kunii and Haramaya districts, fields with out any type of fertilizer also un weeded, intercrop with Sorghum, sown after June, the seed collected from previous yield resulted in highest disease incidence and severity. Among the independent variables, district was the most important variable in its association with CLR incidence(χ2=647.93and 341.18,7df) and severity (χ2 = 219.56 and 112.83, 7df) also with TLB incidence(χ2=758.91and 350.03,7df) and severity (χ2 = 330.92 and 124.04, 7df) when entered first and last into the logistic model, respectively. As recommendation Lower CLR and TLB incidence and severity will obtain from field with fertilizer applied, weed control,inter crop with other crop specialy non host crop, sow the seed on May and buy the seed from market. It is, thus, concluded, that CLR and TLB are the most widely distributed and important foliar diseases of Maize in Hararghe highlands. This work further suggests that management practices should focus on reducing both diseases by using integrated management. Similarly a field experiment was conducted at Haramaya University, reaserch station“Raare” during the 2019 main cropping season. To investgate the management of CLR and TLB complex on maize through resistant variety and fungicide application. The treatment was laid out in factorial experiment in a Randomized Complete Block Design (RCBD) with three replications of each treatment. Four different variety (Afrankallo, Bate, Gibe-2 and Raree- xvii 1) and Mancozeb in different rate (0,1.5,3.0 and 4.5kg ha-1 ) were evaluated in field condition against Puccinia sorghi and Exserohillum turcicum for effective control of CLR and TLB complex respectively. From integrated management combination Bate maize variety with 4.5 kg ha-1 of Mancozeb were proved to be best in managing both disease complex. Bate with 4.5 kg ha 1 of Mancozeb resulted in lowest CLR and TLB disease incidence and severity (60.43, 21.233%) and ( 63.72, 41.767%) respectively,compared to other treatment combination. The highest yield 8392 kg ha-1 and Thousand kernel weight 529 gm were recorded from Bate variety treated with 4.5 kg ha-1 and from Afrankallo variety trated with plot 4.5 kg ha-1 Mancozeb, respectively. The Economic analysis of fungicide rate indicate that the higher marginal rate of return was obtained from Bate variety treated with 4.5 kg ha-1 Mancozeb compared to other treatment combination. In conclusion, integration of varieties with 4.5kg ha-1 Mancozeb foliar sprays were found to be effective treatments in reducing CLR and TLB epidemics and increasing yield. Thus, it is recommended that usage of mancozeb integrated with resistant variety can be used to boost maize production and productivity in the study area and elsewhere with similar agro-ecologies. Moreover,additional management strategies should be undertaken to provide alternatives for managing the diseases.