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To determine the prevalence, incidence and severity of leaf rust (Puccinia hordei) in three different production systems of Ethiopia, 276 barley (Hordeum vulgare) fields from the main rainy season (MRS), residual moisture season (RMS), and short rainy season (SRS) production systems were surveyed during the 2003 and 2004 cropping seasons. Over the 2 years, all the barley fields in RMS, 93% in MRS and 51% in SRS production systems were affected by leaf rust. Mean incidence of leaf rust varied from 34.8% in SRS to 76.4% in RMS and in the same order severity of the disease varied from 5.9 to 15.3%. The mean differences in incidence and severity within the variable classes for the provinces, districts, altitude, fertilizer application, weed density and local cultivar were also high. The independent variables: production systems, provinces, districts, altitude, planting dates, fertilizer application, local cultivar and weed density were significantly associated with high incidence and severity of leaf rust as single predictors in the logistic regression models. However, region and slope of a barley field were not associated with increasing disease intensity. A reduced multiple variable model was fitted using districts, altitudes, fertilizer applications, and weed densities as independent variables. Low rust incidence (⩽50%) and severity (⩽5%) had a high probability of association to Enessie, Agew Midir, Degem and Ankober districts. Incidence of above 50% and severity of above 5% had high probability of association to the RMS production system, Gassera district, and high weed density. In the reduced multiple variable models, province and local cultivar lost importance due to the confounding effect with the districts. |
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