Which condition is most associated with the occurrence of Pythium blight?

Pythium blight is most commonly associated with hot, humid weather combined with limited air movement. This fungal disease thrives in conditions where temperatures are warm—typically above 70°F—and where moisture levels are high, such as after heavy dew formation or intense rainfall. The lack of air movement in these environments exacerbates the problem by preventing the drying of the foliage, which creates an ideal setting for the pathogen to establish and spread.

In contrast, cool and dry weather is less conducive to the development of Pythium blight, as cooler temperatures can slow down the growth of the fungus. Cold, snowy conditions also do not favor Pythium, as the pathogen is not active during periods of frost or snow cover. Similarly, dry and windy environments would not support Pythium blight because the lack of moisture reduces the chances of infection and disease proliferation. Therefore, the combination of heat, humidity, and stagnant air is crucial for the severity and occurrence of Pythium blight, making that condition the most relevant to the disease.