For questions about a plant that's failing to thrive, and where the cause is unknown.
For questions about a plant that's failing to thrive, and where the cause is unknown (it could be disease, pest, or environmental). Ideally, the fullest possible description of the symptoms and growing conditions should be be included, as well as close-ups of the affected part and other parts of the plant.
These questions are good examples of how to ask an effective diagnosis question. Note the photos and descriptions as well as the descriptive title.