The answer to 'why is my grass disease' is that your grass may be suffering from a fungal or bacterial disease. Common causes include excessive moisture, poor drainage, nutrient deficiencies, or pest infestations. Symptoms can include discoloration, wilting, and patches of dead or dying grass.
To address a grass disease, first identify the underlying cause. This may involve testing the soil, inspecting the grass, and ruling out other potential issues. Once the problem is diagnosed, you can take steps to treat the disease, such as applying fungicides, improving drainage, or adjusting your mowing and watering practices. However, for severe or persistent grass diseases, it's best to consult a professional landscaper who can provide a comprehensive assessment and recommended treatment plan.