Description: Black spots on Plumeria flowers can be caused by fungal or bacterial infections due to excessive moisture. Causes: 1. Excessive moisture: Overwatering or high humidity can create conditions favorable for fungal and bacterial growth. 2. Fungal or bacterial infections: Pathogens can infect the flowers and cause spots under prolonged wet conditions. Solutions: Improve air circulation: Ensure good air movement around the plants to reduce humidity levels and discourage pathogen development. Adjust watering practices: Avoid overwatering and allow the soil to dry out between waterings to prevent prolonged flower wetness. Apply fungicides or bactericides: Use appropriate chemical treatments to control fungal or bacterial infections, following the product instructions carefully.