Bacterial wilt

Bacterial wilt is a devastating plant disease caused by the soil-borne pathogen Ralstonia solanacearum. This bacterium invades the plant vascular system, multiplying within the xylem vessels and causing systemic wilting that leads to rapid plant collapse.

The host range of this pathogen is exceptionally broad. It significantly impacts major agricultural crops and ornamental species, including Browallia speciosa, Cyclamen persicum, Fuchsia, Gerbera jamesonii, Geranium, Pelargonium graveolens, and Pelargonium peltatum.

Initial symptoms include transient wilting of leaves during the heat of the day, with recovery occurring at night. As the infection progresses, the wilt becomes permanent. A diagnostic field test often involves observing bacterial streaming, where cloudy threads of bacteria leak from the cut surface of an infected stem.

Development and spread are favored by high temperatures and high soil moisture levels. The bacterium can survive for extended periods in contaminated soil and infested irrigation water, and it is easily transmitted through contaminated horticultural tools, plant debris, and movement of infected transplants.

Management relies primarily on strict integrated pest management (IPM) practices. Key strategies include using pathogen-free planting stock, implementing rigorous sanitation programs for tools and greenhouse surfaces, and applying crop rotation cycles to starve the pathogen of its host plants.