The rapidly spreading thrips carry the virus from plant to plant. Although plants produced outdoors may not be subject to such explosive and dramatic outbreaks because of a less favorable environment and the presence of natural biological controls, it is always possible to introduce a new pathogen or insect into the outdoor production area when purchasing and planting new material. Perennial plant growers need to aggressively attack TSWV and western flower thrips in both greenhouse and outdoor plantings, and must be aware that plants originating from greenhouse production but now planted outdoors may carry the virus. Even if the thrips do not overwinter in Kentucky, vegetatively propagating infected plants will maintain and spread the virus. Garden center operators must also be aware of the biology of TSWV and western flower thrips, especially if they keep herbaceous plants all year.
Many perennials are susceptible to the virus and thrips.
An infected perennial will retain the virus until that plant dies. The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. Educational programs of the Kentucky Cooperative Extension Service serve all people regardless of race, color, age, sex, religion, disability, or national origin.