Robbsia

Robbsia (Latin: Robbsia, formerly known as Pseudomonas andropogonis) is a genus of pathogenic bacteria responsible for significant bacterial infections in various agricultural and ornamental plants. This pathogen poses a substantial threat to yield and quality, particularly in warm and humid climates where environmental conditions facilitate rapid bacterial reproduction.

The host range of this pathogen includes a variety of crops, such as corn, sorghum, carnations, and various legumes. The bacteria typically enter the plant through natural openings, such as stomata or hydathodes, or through wounds caused by pruning, mechanical damage, or insect feeding, establishing an infection within the intercellular spaces of the plant tissues.

Visible symptoms of Robbsia infection manifest as necrotic leaf spots that are often reddish-brown or dark in color, frequently surrounded by a yellow chlorotic halo. Under high moisture conditions, a bacterial ooze may emerge on the leaf surface, which dries into a shiny, film-like residue that serves as a vector for secondary spread by wind, water splashing, or tools.

Environmental conditions are the primary drivers of the disease, with high relative humidity and moderate temperatures being highly favorable for pathogen growth. The bacteria overwinter in plant debris, contaminated soil, or on infected seeds. The rapid nature of spread within greenhouse environments, in particular, makes it essential to manage irrigation practices to prevent foliage wetting.

Management and prevention of Robbsia focus on integrating cultural and chemical practices to reduce infection pressure. Key steps include the use of disease-free seed stocks, strict sanitation of equipment, and the removal of infected plant material from the field or greenhouse. Copper-based bactericides may be utilized as a preventative measure, especially during periods of high disease risk.