Plant borreliosis

It is important to note that while Borrelia is primarily known as a genus of spirochete bacteria causing diseases in animals, the term "plant borreliosis" is sometimes used in specific phytopathological contexts to describe systemic infections caused by phloem-limited pathogens, such as spiroplasmas or phytoplasmas, which affect the transport system of the plant.

The pathogens responsible for these symptoms are specialized bacteria lacking a cell wall. Their survival depends entirely on a host plant and a vector insect. The infection cycle starts when a leafhopper or a similar sap-sucking insect feeds on an infected plant, acquires the pathogen, and subsequently introduces it into the phloem of a healthy host during its next feeding session.

These pathogens affect a diverse range of crops, including vegetables like tomatoes and potatoes, as well as perennial fruit trees and vines. Because the bacteria reside in the phloem, they disrupt the translocation of nutrients and photosynthates throughout the plant, leading to a systemic decline that is difficult to reverse once symptoms appear.

Visible symptoms often include severe chlorosis, leaf curling, stunted growth, and the proliferation of stunted shoots known as the "witches' broom" effect. Flowers may turn green or develop abnormally, and fruit set is frequently reduced or yields poor-quality produce. In many cases, the plant exhibits signs of severe physiological stress, which progressively worsens over the growing season.

Effective management and protection strategies are strictly preventative due to the lack of curative treatments for systemic bacterial infections:

• Rigorous control of insect vectors like leafhoppers and aphids.
• Removal and destruction of infected plants to prevent further spread.
• Maintenance of weed-free fields to eliminate secondary host reservoirs.
• Use of disease-free, certified seeds and nursery stock.
• Implementation of physical barriers or protected cultivation in high-risk areas.