Impatiens necrotic spot

Impatiens necrotic spot is caused by the Impatiens necrotic spot virus (INSV), a member of the genus Orthotospovirus in the family Tospoviridae. This pathogen is a significant economic concern in the ornamental plant industry, as it infects a vast range of hosts including greenhouse flowers and various vegetable crops.

The virus causes a variety of symptoms such as chlorotic or necrotic ringspots, mosaic patterns, stunting, leaf drop, and terminal necrosis. Because these symptoms can vary widely depending on the host species, accurate identification often requires specialized laboratory testing such as ELISA or PCR.

The primary vector for INSV is the western flower thrips (Frankliniella occidentalis). The virus is acquired by larval stages of the thrips and persists throughout their life cycle. This biological transmission mechanism makes it difficult to manage once the virus is established in a greenhouse environment.

Environmental factors play a crucial role in the spread of the disease. Warm temperatures favor the development of both the thrips population and the viral replication within the plant tissue. Greenhouse conditions provide the perfect habitat for the rapid transmission of the pathogen, leading to severe outbreaks.

Management of Impatiens necrotic spot relies heavily on an Integrated Pest Management (IPM) approach. Control measures focus on eliminating the vector population, maintaining strict sanitation, and removing infected plants immediately upon discovery. Cultural practices, such as weed management, are essential because common weeds can serve as reservoirs for the virus.

• Use of certified virus-free plant materials.
• Monitoring for thrips using blue or yellow sticky cards.
• Systemic insecticide programs targeting thrips vectors.
• Exclusion techniques including screens and greenhouse sanitation.