Phylloid disorder

Phylloid disorder is a pathological condition in plants characterized by the transformation of floral parts, such as petals and stamens, into green, leaf-like structures. This condition is primarily caused by phytoplasmas, which are specialized bacteria of the class Mollicutes lacking a cell wall. These pathogens are obligate parasites that colonize the phloem tissues of host plants.

A wide range of crops is susceptible to this disorder, including sesame, legumes, tomatoes, and various ornamental plants. The disease effectively causes sterility in the affected plant parts, as the flower organs lose their reproductive capability, redirecting the plant's energy towards vegetative growth rather than fruit or seed production, which causes substantial yield losses.

The transmission of phytoplasmas is dependent on insect vectors, primarily leafhoppers. The pathogen circulates within the insect's body after it feeds on an infected plant, and then it is injected into the phloem of healthy plants during subsequent feeding. Once inside the plant, the phytoplasma systemically colonizes the phloem, disrupting hormonal pathways and normal developmental processes.

Development and spread of the disorder are heavily influenced by environmental factors such as temperature and the presence of reservoir hosts. Warm conditions facilitate the activity and reproduction of insect vectors, leading to higher disease incidence. Agricultural areas with adjacent weed populations often suffer more severely because these weeds act as overwintering reservoirs for both the pathogen and the insect vectors.

Strategies for the control and management of phylloid disorder are based on integrated pest management practices:

• systematic removal of weeds that serve as reservoirs;
• application of insecticides to manage insect vector populations;
• use of disease-free propagation material;
• maintenance of spatial isolation between susceptible crops and potential inoculum sources.