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.