Hosta-infecting Virii

Need to know: 

• Transmission can occur during vegetative propagation, mechanically by plant sap, or by vectors. 
• Viruses often shorten the lifespan of plants or reduce growth, but are rarely lethal. 
• Preventative measures include only using virus-free plants for propagation and weeding out hosta beds. 

Overview of hosta-infecting viruses 

Viruses are very tiny particles, too small to be seen except under an electron microscope.  Viruses are incapable of reproducing on their own; instead, they invade plant cells and induce these host cells to produce more virus particles.  They then cause disease in plants by disrupting normal cell function, which results in symptom development and a decline in plant health. 

Symptoms of hosta-infecting viruses 

Symptoms can vary depending of the cultivar of Hosta plant but with most cases light or dark green discoloration is present along leaf veins. Leaves can become puckered, distorted, wilted, and eventually tissue death can be seen. Holding an infected leaf and a healthy leaf up to some light can make seeing symptoms a little easier.

Viruses often shorten the lifespan of plants or reduce growth, but they rarely are lethal. Symptoms may also be affected by environmental conditions.  Some common viruses found on hosta are, Hosta virus X (HVX), Impatiens necrotic spot virus (INSV), Tomato ringspot virus (ToRSV), Tobacco rattle virus (TRV), and Arabis mosaic virus (ArMV).

Signs of hosta-infecting viruses 

No evidence of the actually pathogen will be visible by the naked eye. In clinic testing is required to confirm the presence of a virus. 

Disease cycle of hosta-infecting viruses  

Viruses can be transmitted during vegetative propagation if an infected plant is used as the source of propagation material.  They also can be transmitted mechanically by moving plant sap that contains virus particles.  Viruses also can be carried in seeds and pollen and by pests that feed on plants and move infected plant sap from plant to plant, like nematodes, insects, and mites.

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if your plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents can be located at the NPDN website.  If you have a sample from outside of Iowa, please DO NOT submit it to the Plant & Insect Diagnostic Clinic without contacting us.

Management of hosta-infecting viruses 

The best method to manage virus diseases is to avoid introducing these pathogens into the nursery or landscape.  Only use virus-free plants for propagation to avoid transmitting viruses to new plants.  If symptomatic plants are found in a nursery or landscape, they should be removed and destroyed so that the virus cannot be transmitted to healthy plants.  Weeds are known to harbor many different types of viruses, so keeping weeds out of hosta beds will help, as well.  There are no pesticides available to control virus diseases in plants. for more information on virus and other disease and pests of hosta see the publication Hosta Diseases and Pests.