Tomato aspermy

Tomato aspermy is caused by the Tomato aspermy virus (TAV). It is classified within the kingdom Viruses, family Bromoviridae, and genus Cucumovirus. As an RNA-based plant pathogen, it affects a wide range of hosts, primarily focusing on members of the Solanaceae family as well as various ornamental species such as chrysanthemums.

The characteristic symptoms of the infection include severe leaf deformation, often resulting in filiform (thread-like) foliage and mosaic patterns. The most diagnostic sign is the effect on fruit development: affected tomatoes are typically small, misshapen, and seedless, which is why the condition is called "aspermy," signifying the lack of viable seeds.

The biology of TAV is heavily dependent on insect vectors for dissemination. Aphid species, most notably the green peach aphid (Myzus persicae), serve as the primary transmission agents. The virus overwinters in perennial weeds and ornamental reservoirs, which act as initial inoculum sources when spring temperatures rise and insect populations become active.

Environmental conditions that favor aphid proliferation directly correlate with the spread of the virus. TAV is transmitted in a non-persistent manner, meaning aphids can acquire the virus during very short feeding probes on infected tissue and immediately transmit it to healthy plants. Mechanical transmission via tools and manual handling also plays a role in the dissemination within greenhouse environments.

The economic impact is significant due to both reduced yield and poor fruit quality. Effective control measures rely on integrated pest management (IPM). Key strategies include maintaining high levels of hygiene by removing weed hosts, applying insecticides to manage aphid populations, and ensuring that ornamental plants are kept separate from vegetable crops to prevent cross-infection.