How does bacterial wilt spread?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.Bacterial wilt has the capability for rapid and explosive spread through cucumber plants. Cucumber beetles spread this disease. Bacteria enter plants through small feeding wounds. I have watched healthy vines decline to the ground so quickly, within a one-night period. Knowing this information about the transmission of the disease can help potentially stop outbreaks before they impact entire crops.
Carrier Phase
- Beetle vectors: Striped/spotted beetles carry Erwinia tracheiphila bacteria
- Overwintering: Bacteria survive winter in beetle digestive systems
- Spring activation: Infectivity peaks during first feeding
Infection Phase
- Entry points: Bacteria enter through leaf/stem feeding wounds
- Vascular spread: Multiply in xylem tubes blocking water flow
- Rapid colonization: Full systemic infection within 48 hours
Symptom Phase
- Initial wilting: Daytime drooping with overnight recovery
- Permanent collapse: Complete vascular failure within 5-7 days
- Sap test confirmation: Milky white bacterial ooze from cut stems
The cycle begins with feeding from a beetle. Each bite transfers bacteria into their tissue. I have counted infections that started with just a single beetle. The bacteria in the vascular system will grow exponentially. They form sticky obstructions. The water is prevented from moving upwards. The plant becomes dehydrated internally.
There is no cure for this infection once it is established. Still, I take the precaution of removing all wilted plants immediately. This action should prevent the beetles from spreading bacteria to any further plants. The goal of prevention is to control the beetle population before flowering begins. Row covers afford protection while the plants are young. The goal is to control beetles before they have a chance to feed. Protect your plants!
Be aware of the early signs of the issue. Be certain to look for midday wilting during warm, sunny days. The stem test should be performed every day throughout beetle season. Cut off the lower stem of a plant and squeeze it. Milky ooze confirms the infection. Quickly dispose of affected plants. Sanitize tools after each use.
Read the full article: Cucumber Beetle Damage: Signs and Solutions
