Streptobacillosis

Streptobacillosis is a bacterial plant disease caused by pathogens of the Streptobacillus genus. This disease primarily affects the vascular system of plants, leading to severe disruptions in nutrient and water transport. As a systemic disease, it causes wilting and eventual necrosis of the stems and leaves, often leading to the total loss of individual plants if not addressed promptly.

This infection typically targets a wide range of horticultural crops, including solanaceous vegetables and various orchard trees. The pathogen thrives by entering the host plant through stomata, lenticels, or wounds created by farm machinery or insect vectors. Once inside, the bacteria multiply rapidly within the xylem vessels, obstructing them with their biomass and metabolic byproducts.

Clinical signs of the disease start with leaf yellowing and mosaic patterns, followed by brown necrotic spots. As the bacterial population increases, the stems often show internal darkening, and a milky or yellowish exudate may appear on the surface of the plant tissue. In advanced stages, the plant shows rapid wilting that does not recover even after irrigation, followed by tissue collapse.

Environmental conditions such as high humidity and temperatures ranging from 20°C to 28°C are critical for the development of streptobacillosis. The pathogen spreads rapidly through water splashes during heavy rain or overhead irrigation. It persists in soil, contaminated seeds, and crop debris, making it a difficult pathogen to eradicate once established in a field or greenhouse environment.

The economic impact of streptobacillosis is severe, resulting in significant yield reductions and lower produce quality. Management strategies focus on an integrated approach:

• Using certified disease-free seeds and planting material.
• Implementing strict crop rotation protocols to break the pathogen lifecycle.
• Sanitizing tools and machinery to prevent mechanical spread.
• Applying copper-based bactericides or biological control agents during high-risk periods.
• Ensuring proper plant spacing to facilitate air circulation and reduce humidity.