Plant mycoplasmosis

Plant mycoplasmosis, now scientifically classified as phytoplasmosis, refers to infections caused by phytoplasmas — specialized wall-less bacteria that inhabit the plant phloem. These pathogens disrupt the translocation of assimilates, leading to severe physiological collapse of the host plant.

This disease has a broad host range, impacting various economically significant crops. Common victims include tomato, potato, grapevine, and several stone fruit species. In addition to agricultural crops, many herbaceous weeds act as asymptomatic reservoirs, allowing the pathogen to persist in the ecosystem during the off-season.

The primary clinical symptoms include chlorosis, stunting, and the proliferation of axillary buds, resulting in a bushy appearance known as "witches' brooms." Furthermore, infected plants often show floral abnormalities, such as phyllody (transformation of floral organs into leaf-like structures) and flower greening, which typically leads to yield loss.

Transmission occurs almost exclusively through phloem-feeding insect vectors, primarily leafhoppers, planthoppers, and psyllids. When these insects feed on an infected plant, they acquire the phytoplasma and subsequently transmit it to healthy plants during their feeding cycle. Environmental factors like drought or high humidity can indirectly favor the populations of these insect vectors.

Management strategies for phytoplasmosis are strictly preventative, as there is no curative chemical treatment for established infections. Key measures include:

• rigorous control of insect vectors using systemic insecticides;
• eradication of infected plants to remove the inoculum source;
• management of weed hosts surrounding cultivated areas;
• use of high-quality, disease-free planting material.