Erwinia psidii

Erwinia psidii is a highly destructive bacterial pathogen known for causing bacterial necrosis in various plants, most notably in guava (Psidium guajava). This phytopathogen belongs to the genus Erwinia and is recognized as a significant threat to tropical and subtropical fruit production globally.

The host range of this bacterium is primarily focused on the Myrtaceae family. The disease causes severe damage to vegetative growth, affecting young leaves, shoots, and reproductive structures, which significantly reduces plant vigor and overall fruit yield if left unmanaged.

Symptoms typically manifest as small, dark, water-soaked lesions on young tissue, which rapidly expand into necrotic areas. As the infection progresses, the tissues shrivel and dry out, leading to the systemic death of twigs and branches. In severe cases, the entire plant can succumb to the infection due to vessel colonization.

The development of the disease is heavily influenced by environmental conditions, particularly high relative humidity and frequent rainfall. These factors favor the proliferation and dissemination of the bacteria, which can be transmitted through splashing rain, wind, contaminated pruning tools, and insect vectors that transfer the pathogen between healthy and infected tissues.

Effective management strategies require an integrated approach. Essential practices include implementing strict sanitation protocols, such as removing and destroying infected plant parts, and thoroughly disinfecting pruning equipment. Preventive applications of copper-based bactericides can also reduce the incidence of primary infection during periods of peak susceptibility.