Small, white mushrooms growing on the leaf blades of tall fescue may have been caused by:

The presence of small, white mushrooms on the leaf blades of tall fescue is typically indicative of a fungal infection. Fungi thrive in environments where humidity and moisture levels are high, and the appearance of mushrooms suggests that fungal growth is taking place, often linked to decaying organic matter or overly moist conditions.

White patch, on the other hand, specifically refers to a grass disease caused by the fungus Sclerotinia homeocarpa, which results in white patches on the turf. While it can be associated with fungal issues in grass, it does not directly describe the formation of mushrooms on the leaf blades. Therefore, while bacterial and fungal diseases such as white patch can create various symptoms in grass, the actual appearance of mushrooms aligns more closely with a broader category of fungal infection rather than white patch itself.

Overwatering can create conditions that favor fungal growth, leading to mushrooms; however, it is not the primary cause. Insect damage is also unlikely to be a factor in the development of mushrooms, which are specifically signs of fungal activity rather than damage from insects.