Podosphaera fuliginea and Erysiphe cichoracearum are the two most commonly recorded fungi causing cucurbit powdery mildew.

In the past, Erysiphe cichoracearum was considered to be the primary causal organism throughout most of the world.

[1] The host tissue is frequently stunted, distorted, discolored, and scarred.

[1][4] Podosphaera fuliginea uses haustoria to gain access to the leaf epidermal cells.

The fungus is usually spread during the spring through mycelium from infected plant, or through ascocarps.

The mycelium grows rapidly during the warm summer months with an optimum temperature of about 10–32°C (50–90 degrees F).

[1] The conidia of the fungus are spread through the air and thus can travel over great distances.