INSV was diagnosed on this garden impatiens. The grower observed leaf spots and poor growth on impatiens. New growth was distorted and small. Closer observation revealed black (firm) stems as seen here. A sample of symptomatic tissue (black stems, leaf spots) tested positive for INSV using an on-site test kit.
INSV and TSWV (Tomato Spotted Wilt Virus) are two members of the Tospoviruses which are vectored exclusively by Western flower thrips (Frankliniella occidentalis). These viruses have an extremely wide host range (more than 600 species of plants are susceptible). There is no cure or chemical treatment for plant viruses. Discard affected plants, eradicate weeds that may be hosts, and control thrips populations. Inspect plant material at arrival or quarantine new shipments. Do not grow vegetable transplants and ornamental bedding plants in the same greenhouse.
Fact Sheet: Reviewing Western Flower Thrips and Topsoviruses
