Plant mycoplasmoses

Plant mycoplasmoses are serious diseases caused by organisms of the order Mycoplasmatales, specifically phytoplasmas. These unique pathogens lack a rigid cell wall, which allows them to inhabit the phloem of host plants, where they multiply and disrupt the systemic translocation of photosynthates and other vital nutrients.

These diseases exhibit a wide host range, severely affecting solanaceous crops like tomatoes and potatoes, as well as fruits and ornamentals. The pathogens are notoriously difficult to detect in early stages, as they often manifest through subtle growth irregularities before progressing to severe physiological decline.

Symptoms typically include yellowing (chlorosis), stunting, proliferation of axillary buds leading to «witches' broom» growth, and flower abnormalities such as virescence (greening of petals) or phyllody. These symptoms indicate a systemic infection that profoundly impacts the plant's metabolic pathways and reproductive capacity.

The transmission of these diseases is almost exclusively dependent on insect vectors, primarily leafhoppers, planthoppers, and psyllids. When a vector feeds on an infected plant, it acquires the phytoplasma, which then circulates through the insect's body before being transmitted to a healthy plant during subsequent feeding sessions.

Control strategies for mycoplasmoses are primarily prophylactic. Because direct treatment of the pathogen within the plant is rarely effective, management focuses on:

• Strict weed control to eliminate reservoir hosts.
• Rigid quarantine measures for propagative materials.
• Deployment of systemic insecticides to manage vector populations.
• Utilization of resistant cultivars and virus-indexed planting stock.