Large beardtongue has common pests like aphids, spider mites, whiteflies, which can damage by extracting fluid from the plant. These annoyances can lead to drooping, yellowing leaves, stunted growth. To prevent problems, normal checking of the plant and use of insecticidal soap or neem oil works well.
For illnesses, Large beardtongue is prone to powdery mildew, a fungal problem that looks like a white powdery stuff on leaves. This sickness can weaken the plant and stop photosynthesis. Good air flow, avoiding overhead watering, using fungicides can help prevent powdery mildew. Decline of Large beardtongue can be from a mix of pest issues and illnesses, causing stress and eventually deterioration.