Purpose: Northern Leaf Blight (NLB), caused by Exserohilum turcicum, is a major constraint to maize production in Ethiopia. This study aimed to investigate the epidemiological drivers and spatial patterns of NLB across major maize-growing regions to inform integrated management strategies. Methods: A field survey was conducted across 18 districts in Oromia, Amhara, and SNNPR regions over two cropping seasons (2021–2022), encompassing 1080 farms. Disease severity was quantified using Percent Severity Index (PSI) and Lesion Area (LA). Spatial, agronomic, and environmental data were analyzed using chi-square tests, correlation analysis, and logistic regression. Results: Pronounced spatial and temporal variations in NLB severity were observed. Oromia exhibited the highest overall disease pressure (PSI: 63.0%), followed by SNNPR (62.1%) and Amhara (60.6%). At the zonal level, Sidama recorded the most severe infections (PSI: 70.6%). Moist and semi-moist mid-altitude zones showed the highest disease pressure (PSI: 70.3%), attributed to cooler temperatures and higher rainfall (> 1200 mm). Temporal trends showed higher severity in 2021 (PSI: 64.0%) than 2022 (60.2%). Cropping systems and cultivar selection significantly modulated disease outcomes. Sole cropping was associated with higher severity (PSI: 68.4%), while intercropping reduced risk (PSI: 54.2%). Susceptible cultivars like BH540 (PSI: 77.1%) suffered severe infections, whereas resistant hybrids such as BH661 (PSI: 51.7%) mitigated impact. Logistic regression identified late planting (OR = 42.53, 95% CI: 17.63–102.61), susceptible cultivars (OR = 24.51, 95% CI: 7.26–82.73), and high-risk agro-ecology (OR = 7.22–16.07) as the top risk factors. Conclusion: This study highlights the multifactorial nature of NLB epidemics. Effective management requires spatially-targeted integrated strategies combining resistant cultivars, optimized planting schedules, diversified cropping systems, and balanced nutrition to enhance maize productivity and safeguard smallholder livelihoods in Ethiopia.
Mesele Haile, Z. Bekeko, Dagne Wegary et al.· Journal of Crop Health· 0 citations
Septoria tritici blotch (STB), caused by Zymoseptoria tritici, is a major disease of spring wheat in Ethiopia and worldwide. This study evaluated 45 spring wheat genotypes for adult plant resistance under natural infection at Holetta Agricultural Research Center during the 2022 and 2023 seasons. Disease was assessed using two methods: (i) visual estimation of disease severity (DS) as the percentage of leaf area with necrotic lesions bearing pycnidia; and (ii) pycnidial density within lesions scored on a 0–5 scale to classify resistance levels. Combined analysis of variance across years showed significant effects (P ≤ 0.01) of year, genotype, and genotype × year interaction. Genotype accounted for 42.81% of the total variance in mean disease severity (from early grain filling to 70% flag leaf infection with pycnidia-bearing necrosis) and 42.3% of the variance in AUDPC. Mean severity ranged from 46.46% to 73.49% in 2022 and 8.73% to 71.71% in 2023, while pycnidial density ranged from 2.23% to 35.7% and 1.21% to 45.47% in 2022 and 2023, respectively. Four reaction classes were identified: resistant (24.4% and 25.2%), moderately resistant (30.4% and 24.4%), moderately susceptible (22.2% and 20.7%), and susceptible (22.96% and 29.63%) in 2022 and 2023, respectively. ‘Catbird’ was the most susceptible cultivar, whereas ‘Gondo’ was the most resistant. Cluster analysis grouped the cultivars into eight clusters based on STB severity and AUDPC, including two clusters (six genotypes) with resistant responses. These clusters did not include the differential lines used to characterize Z. tritici races, suggesting that the underlying resistance genes require further molecular characterization. The resistant genotypes (Blouk #1, 6B662, Coulter, Erik, Gondo, and ETW17–115) were effective against pathotypes virulent to major Stb genes present in Veranopolis (Stb2, Stb6), Shafir (Stb6), and Estanzuela Federal (Stb7). Disease severity and AUDPC were negatively correlated with plant height, number of tillers per plant, spike length, number of seeds per spike, thousand kernel weights, and grain yield. Correspondence and principal component analyses identified three major groups among the 45 genotypes: resistant, high-yield potential, and susceptible. The resistant genotypes identified here provide valuable material for breeding programs targeting improved resistance to Z. tritici.
Habtewold Kifelew, H. Terefe, Bekele Kasa et al.· PLoS ONE· 1 citation