the vine that turned brown
- Size
- Microscopic
- Lifespan
- Survives in plant debris.
- Diet
- Parasitic on Actinidia species.
- Habitat
- Bacterial infection affecting kiwifruit vines.
- Range
- Bay of Plenty, Gisborne, Northland.
- Endemism
- Introduced
- Main Threats
- Wind, rain, and human activity spread bacteria.
- Population
- Major impact on horticulture. Managed through strict biosecurity.
- Conservation Status
- data_deficient
- Human Risk
- harmless
- Handling Note
- strict biosecurity protocols apply in kiwifruit growing regions
- Conservation Note
- Introduced bacterial pathogen causing severe disease in kiwifruit vines; managed through industry-led biosecurity and resistant cultivar development.
- Te Ao Māori
- While not a native species, PSA had a profound impact on rural communities and the national economy. It highlighted the vulnerability of industrial agriculture to biological shocks. The response involved significant collaboration between industry, government, and researchers, showcasing a rare instance of unified action in the face of ecological threat.
Growers noticed it first. In 2010, kiwifruit vines in Te Puke began to wilt. Leaves turned brown. Canes collapsed. The culprit was Pseudomonas syringae pv. actinidiae, known as PSA. It is a bacterium that enters the plant through natural openings or wounds. Once inside, it multiplies rapidly, blocking the vascular system. The vine starves. White ooze may appear on canes, a sign of advanced infection. The economic impact was immediate and severe. Kiwifruit is one of New Zealand's largest export earners. Entire orchards were destroyed. Livelihoods vanished overnight. The response was a masterclass in crisis management. Industry levies funded research. Strict biosecurity protocols were enforced. Resistant varieties were fast-tracked. The landscape of Bay of Plenty changed. Old green kiwifruit blocks were ripped out and replaced with gold varieties, which showed some tolerance. The ecological lesson is sharp. Monocultures are fragile. When you plant thousands of hectares with the same genetic stock, you invite disaster. PSA exploited that uniformity. It did not care about the economy. It only cared about the host. Today, the disease is managed, not eradicated. It persists in the environment. Growers live with it. The scars remain in the form of changed farming practices and a heightened awareness of biological risk. The bacterium is a reminder that nature does not respect balance sheets. It adapts. It spreads. It waits for weakness.