What environmental conditions enhance the growth of powdery mildew?

Powdery mildew thrives in conditions characterized by cool nighttime temperatures, high relative humidity, and abundant plant growth. This fungal disease is facilitated by high moisture levels in the air, which promote spore germination and colonization on host plants. During the night, cooler temperatures paired with high humidity create an ideal environment for the pathogen to flourish. The lush growth of plants provides a suitable surface for the mildew to adhere to and develop on, as dense foliage can trap moisture, leading to the sheltered conditions that are favorable for infection.

While other options present different temperature and humidity conditions, they do not align with the optimal environment that encourages the growth of powdery mildew. For example, high temperatures and low humidity create dry conditions that are less conducive to pathogen development, while sparse plant growth would limit the available surfaces for the mildew to grow. Overall, option B encapsulates the specific environmental factors that collectively contribute to the proliferation of powdery mildew in affected plants.