Lucky for you, Purple Fountain Grass is pretty resistant to diseases and pests. However, there are a few common problems to keep an eye out for when planting your perennial. The most common disease found in these plants is a fungus. This is due to trapped moisture or humidity between the dense clumps of grass. To avoid this, place your new plant several feet apart from others to increase the amount of airflow. You may also notice slugs and snails around your grass, don't panic! They may occasionally eat some of your plant's foliage, but they are highly unlikely to cause any serious, long-lasting damage.