Which of the following symptoms is characteristic of Brown Patch disease?

Brown Patch disease is primarily characterized by the appearance of irregular brown patches on grass, which can vary in size. These patches often have a distinctive look, with grass blades within the affected area turning brown or tan while the patches themselves can be surrounded by a darker green ring or halo. This symptom is typically a result of the fungus Rhizoctonia solani, which thrives in humid conditions and can cause significant damage to turf grasses.

The other symptoms listed, while they may occur in various turf diseases, do not specifically define Brown Patch. Rapid wilting is more associated with drought stress or certain root diseases, dark leaf margins can signify different types of stress or disease including cold damage or nutrient deficiencies, and water-soaked lesions are common symptoms of other fungal infections. Therefore, the presence of brown patches is the hallmark symptom that specifically identifies Brown Patch disease.