Influence of Sowing Dates and Weather Factors on Turcicum Leaf Blight and Grain Yield in Maize

The effect of five sowing dates (May 6, 13, 20, 29 and June 3, 2004) and weather factors on development of Turcicum leaf blight and grain yield in maize cv. ‘C⁸’, studied during Kharif, 2004, indicated maximum apparent infection rate (r) during pre-taselling to taselling growth stage for all the sowing dates. The maximum (28.3–30.0^oC) and minimum (12.5–17.2_oC) temperature and relative humidity (84.9 - 78.5 and 62.4–49.3%, respectively), mean rainfall (2.2–9.2 mm) and the total number of rainy days (0–2) were significantly but negatively correlated with the disease index. Highest grain yield (56.0 q ha⁻¹) and minimum AUDPC value (1990.1) were obtained in earliest sown crop (6^th May). With the delay in the sowing date, an increase in AUDPC value with simultaneous decrease in grain yield was recorded such that maximum AUDPC value (2545.7) and minimum grain yield (34.3 q ha⁻¹) were obtained in the late sown (3^rdJune) crop.