Influence of Metrological Parameters on the Development of Exserohilum turcicum (Pass.) Leonard and Suggs on Maize in Tanzania

Abstract

Twenty maize varieties and inbred lines were used to determine the effect of weather parameters on the development of Exserohilum turcicum, in­citant of northern leaf blight disease in Tanzania. Artificially inoculated field ex­periments were conducted in Morogoro, Arusha, and Mbeya Regions in 2013 and 2014 in a 15 m² plot size, replicated three times in a randomized complete block design. The disease severity indexes were recorded at weekly interval from 65 days after sowing and subsequently for 5 weeks, while weather reports were obtained from Tanzania Meteorological Agency. Data were subjected to ANOVA, correlation coefficient, and coefficient of determination (R²), while means were separated using LSD (P ≤ 0.05). Results on disease severity index indicated high significant (P ≤ 0.05) differences in the region, year, and interaction between re­gion and year. Rainfall, relative humidity, and temperature significantly favored maize infection by E. turcicum in Mbeya, Arusha, and Morogoro to 76.1%, 58.3%, and 41.8%, respectively. Negative significant (P ≤ 0.05) correlation coefficients were found between minimum temperature and severity index in Morogoro (r = -0.694) and Arusha (r = -0.748) Regions while significantly positive correlation existed between relative humidity and severity index (r = 0.739) in Mbeya Re­gion. Although the weather parameters encouraged prevalence of northern leaf blight disease in all the regions, relative humidity (69%) in Mbeya favored high development of the pathogen, while minimum temperatures encouraged infec­tion in Morogoro (18.6ᵒC) and Arusha (14.2ᵒC) Regions.