by Dr. Stephen Nameth Bacterial wilt or blight of Geranium (Pelargonium x hortorum), caused by Xanthomonas campestris pv. pelargonii (Xcp), is the most destructive disease associated with greenhouse geranium production today. The bacterium enters the host through wounds and natural openings in the host. Once in the host, the bacteria multiply and spread systemically through the plant's vascular tissue.
The sheer number of bacteria along with the extracelluar carbohydrates produced by the bacteria, literally plug the infected plants vascular tissue. The plant can no longer transport water. In the advanced stages the infected plant will wilt and subsequently die.
If infected plant goes undetected, the bacteria can move rapidly from plant to plant, and in a matter of no time infect the entire crop. There is no known resistance or tolerance to Xcp in P. hortorum.
The primary method of controlling this destructive disease is to keep it out of the greenhouse. The purchase of or production of Xcp - free plant material is critical in keeping the greenhouse free of this pathogen. If infected plants are allowed to enter the greenhouse, strict attention must be paid to plant handling and watering practices in an effort not to spread the disease.
The OSU Plant Pathology Department
