Poinsettia Growers Should Monitor for This Virus

Posted by Brian Sparks|August 16, 2022

Poinsettia mosaic virus (PnMV) is a pathogen that has been sporadically reported worldwide over the last 40 years. The host range of PnMV is limited primarily to Euphorbia sp., of which poinsettia (E. pulcherrima) is most susceptible to infection. Depending on the severity of PnMV symptom expression, infected poinsettias could be deemed unmarketable, which would pose major implications to greenhouse growers.

A recent e-GRO alert describes and provides photos of symptoms caused by PnMV on poinsettia. Infection of PnMV during greenhouse poinsettia production generally occurs during propagation, when infected stock plants are used to generate propagules. Symptoms tend to be most pronounced when plants are grown under cooler conditions.

It is important to note that PnMV can show a wide range in symptom expression in poinsettias. Mosaic or mottling can be subtle and leaf distortion minimal, allowing the symptoms to go largely unnoticed during production.

While PnMV has not been reported to have any known vectors, other members of the family of viruses to which PnMV belongs, Tymoviridae, are commonly transmitted via sap by flea beetles. Since the virus is transmissible via sap, this means that mechanical transmission is possible, and that direct contact between infected plant tissue and healthy plants could cause infection.

Poinsettia mosaic virus is not transmissible through seeds or pollen, and it is unlikely that the virus is transmitted through soilless substrate.