Oleander knot
Pseudomonas savastanoi pv. nerii
What are Oleander and Olive knot?
Pseudomonas savastanoi pv. nerii and Pseudomonas savastanoi pv. savastanoi are bacterial pathogens that target oleander and olive plants. They cause distorted, swollen growths on stems and bark, as well as galls on oleander flower buds and leaves. Although the galled parts may wither and die, the overall health of the plants is usually not significantly affected. These bacteria mainly impact the appearance of the affected plants, but they typically do not pose a severe threat to their overall well-being.
How do Oleander and Olive knot occur?
They reproduce and spread through various means. The bacteria persist in cracked and rough bark, allowing them to survive. During wet weather in winter and early spring, they multiply and are disseminated through rain splashes and contaminated tools. The bacteria enter plants through fresh wounds, such as pruning cuts and frost cracks, and leaf scars on branches. Once inside, they colonize and reproduce, forming gall-like growths on the stems, bark, flower buds, and leaves of infected plants.
Symptoms
1 - Effects on Plants
Pseudomonas savastanoi pv. nerii and Pseudomonas savastanoi pv. savastanoi cause galls, leading to distorted and swollen plant parts. This can potentially affect the overall growth and form of the affected plant.
2 - Effects on the Environment
The presence of Pseudomonas savastanoi pv. nerii and gall formation can impact the appearance and dynamics of plant communities, potentially altering the environmental aesthetics.
Solutions
1 - • The bacteria can be spread through contaminated tools, rain splashes, and movement of infected plant material, contributing to disease dissemination within and between plantings. • The presence of Pseudomonas savastanoi pv. nerii and gall formation can impact the appearance and dynamics of plant communities, potentially altering the environmental aesthetics.
• Start with healthy, disease-free nursery stock when planting oleander or olive trees. • Maintain good hygiene in the garden by regularly cleaning and disinfecting pruning tools to prevent the spread of bacteria. • Minimize the use of overhead irrigation, as it can promote the spread of the bacteria. Instead, opt for methods such as drip irrigation to keep the foliage dry. • Prune and remove galled plant parts, ensuring proper disposal away from healthy plants.
2 - Treatment
1. Antibiotic Treatments: Consult with a local agricultural extension service or professional for specific recommendations. 2. Antibiotics like streptomycin or copper-based products may be recommended for managing bacterial infections, but usage should follow local regulations and instructions.
