Bacterial blight (BL), caused by Xanthomonas campestris pv. malvacearum (Smith) Dye, is a common disease affecting the growth, development and yield of cotton ( Gossypium hirsutum L.) in Pakistan. Field trial was conducted for a season to determine the influence of environmental conditions representing heavy and low rainfall periods, wind speed and direction on disease incidence by growing 101 commercial varieties. However, out of 101 varieties, a total of 68 varieties were moderately susceptible response while 8 were susceptible to bacterial blight disease. A total of 25 varieties were moderately resistant to bacterial blight disease. No variety was resistant to bacterial blight disease. Except radiation and wind speed, overall correlation of maximum and minimum air temperature, relative humidity, rainfall and pan evaporation with bacterial blight disease severity was statistically significant. The poor correlation of wind speed with disease severity may also be due to frequency and amount of air currents received in a certain adjoining areas of Faisalabad district of Pakistan and its indirect role to create humid conditions. Similarly relative humidity is different at different levels of crop canopy and largely depends upon the amount of moisture resulted due to rain showers and irrigation.
