The Plumeria Pests and Diseases Guide is an essential resource for identifying, preventing, and treating the most common threats to plumeria plants, including pests, fungi, and environmental stressors. This guide offers detailed information on how to recognize early signs of trouble, from insect infestations to fungal infections, and provides practical solutions to address these issues. It also covers strategies for managing environmental factors such as excessive humidity, temperature fluctuations, and poor soil conditions, which can weaken plumeria. With expert tips on natural and chemical treatments, as well as proactive care practices, this guide ensures your plumeria remains healthy, resilient, and free from common ailments, allowing it to thrive season after season.
How to Identify Stem Canker in Plumeria – Sunken Lesions, Cracks & Localized Rot
How to Identify Stem Canker in Plumeria – Sunken Lesions, Cracks & Localized Rot
Stem canker is a serious but often overlooked plumeria disease that causes sunken, discolored lesions on the branches or trunk. Caused by opportunistic fungal pathogens (often following mechanical damage or sunburn), cankers can slowly girdle stems, leading to reduced vigor, dieback, and in severe cases, structural collapse.
This article helps you identify the key symptoms of stem canker in plumeria early—before the infection spreads too deeply into plant tissue.
What Is Stem Canker?
Stem cankers are localized, sunken, or discolored areas of diseased tissue on the plumeria’s woody branches. They are often caused by:
- Fungal pathogens (Botryosphaeria, Phomopsis, or Fusarium spp.)
- Entry through wounds, sunburns, or insect damage
- Moist, humid conditions that promote fungal spread
- Improper pruning, bruising, or water sitting on old scars
Unlike generalized stem rot, cankers are contained to a specific site but can worsen over time.
Key Symptoms of Stem Canker in Plumeria
1. Sunken or Cracked Bark Lesions
- Darkened patches on the bark
- Lesion may appear wrinkled, depressed, or cracked
- Tissue is often dry on the surface but soft underneath
2. Oozing or Sap Weeping
- Small amount of amber, brown, or clear sap may leak from the lesion
- In some cases, dried sap crystals appear at wound edges
3. Discoloration Beneath Bark
- Scraping outer bark reveals brown or reddish tissue
- Edges of the lesion may show clear boundaries between healthy and diseased wood
4. Localized Dieback
- Branch above the lesion may fail to leaf out or grow stunted
- Buds may dry up or fall off
- Entire branch may collapse if canker expands unchecked
5. Slow Progression Compared to Rot
- Unlike stem rot, which moves quickly and softens entire branches, cankers typically remain localized for weeks or months
- May go dormant or worsen seasonally
Common Canker Locations
- Midway down branches, often near a pruning scar
- Base of older leaf scars or nodes
- Branches exposed to mechanical damage (e.g., broken tips or stake wounds)
- Sunburned areas on thin, upright stems
When and Where to Inspect
| Timing | Areas to Inspect |
|---|---|
| After physical damage | Recently cut or bruised stems |
| During humid periods | Lower canopy and inner branch angles |
| Mid to late summer | Stems exposed to intense sun or overhead water |
| Dormant season | Overwintered scars or unsealed pruning cuts |
Stem Canker vs. Other Plumeria Issues
| Symptom | Likely Cause | How to Tell |
|---|---|---|
| Blackened tip with soft mush | Stem rot | Spreads fast, smells bad, affects tips first |
| Cracked lesion, dry surface | Stem canker | Sunken, localized, may ooze sap |
| Flat scar, no spread | Old pruning wound | Bark is hardened and not actively spreading |
| Swollen knot or callus | Mechanical injury response | No discoloration or oozing |
Tools for Identification
- Sterile blade or knife to shave outer bark
- Magnifying lens to inspect lesion edges and fungal texture
- Paper towel swipe to check for sap
- Notebook or photos to monitor lesion size over time
Conclusion
Stem canker in plumeria may begin as a small crack or sunken scar—but without early detection, it can become a long-term health problem. Knowing the difference between harmless wounds and active cankers is critical to catching and treating the infection in time. In the next article, we’ll cover how to treat plumeria stem cankers with safe pruning, sealing, and recovery protocols.