Effect of weather parameters on development of early blight of Tomato caused by Alternaria solani in polyhouse and field conditions

Field studies were conducted to determine the environmental factors associated with infection of field and protected plants. The overall mean disease incidence and intensity was 84.8% in protected environment and 82.2% in field condition during last week of October in 2014 and 2015, respectively. Results revealed that correlation coefficient (r) showed strong positive correlation (r = +841) with minimum temperature ranged (24.8–23.8°C) with maximum relative humidly (r = +0.792) ranged (91.1–84%) and negatively correlated with maximum temperature and minimum relative humidity (r =-0.170 &-0.826), (30.3–33.9°C) and (70.7–47.1%), respectively. In the case of field condition, r was (−0.37) with maximum (+0.94) minimum temperature, (+0.92 &-0.92) with maximum and minimum relative humidity and-0.62 rainfall, respectively. Disease severity was found comparatively higher in the temperature range from (24.8–35.4°C) and (20.0–33.9°C) coupled with relative humidity (66.5–91.1%) and (38.4–84.1%), respectively in polyhouse (protected) and field conditions.