Spiroplasmosis

Spiroplasmosis is a serious vascular disease in plants caused by bacteria of the genus Spiroplasma. These unique prokaryotes belong to the class Mollicutes and lack a traditional cell wall, allowing them to thrive and move within the phloem of infected host plants, where they severely disrupt nutrient translocation.

Various crops are susceptible to these pathogens, with Spiroplasma citri significantly affecting citrus orchards and Spiroplasma kunkelii being a major concern for maize production worldwide. The host range often extends to a wide variety of weeds and ornamental plants that serve as reservoirs for the bacteria.

Common clinical signs of the disease include stunted plant growth, leaf chlorosis, interveinal yellowing, and the formation of small, malformed fruits. Infected corn plants, for instance, may display characteristic reddish-purple leaf discoloration and poor cob development, leading to significant yield loss.

The transmission of Spiroplasma is primarily vectored by phloem-feeding insects, specifically leafhoppers (Cicadellidae). Once the insect ingests the bacteria while feeding, the pathogen colonizes the vector's salivary glands, allowing for efficient transmission to healthy plants during subsequent feeding sessions.

Management of spiroplasmosis is challenging and relies heavily on integrated pest management (IPM) strategies to suppress the vector population and minimize disease pressure:

• Applying systemic insecticides to control leafhopper populations.
• Removing weed hosts that harbor the pathogen throughout the year.
• Selecting resistant varieties or hybrids whenever they are commercially available.
• Implementing rigorous sanitation by removing and destroying symptomatic plants to eliminate sources of inoculum.