- Canker (Phomopsis gardeniae): Swollen stem base; yellow discoloration beneath the bark.
- Bacterial leaf spot (Pseudomonas gardeniae): Leaf spots ranging from pinpoint dots to rounded brown spots (1/4 in. diameter) with water-soaked margins. Remove infested leaves.
- Root-knot nematodes: Swollen, knobby areas (galls) on a stunted root system. Discard infested plants.