Anyone who grows hostas in a serious way has almost surely heard of Hosta Virus X. This article is designed to inform the casual hosta gardener of the facts that they need to avoid bringing plants in that are affected by the virus if at all possible and to know what to do if it is present in their gardens.
What is Hosta Virus X?
It is a pathogen which disfigures the leaves of infected plants. It is not the first virus to be detected in hostas but it is of concern for the primary reason that it greatly affects the looks and health of the infected plants.
Experts feel that it may have originated either in the U. S. or Japan where it was exported to Europe. It then found its way back to the U.S. in commercial shipments.
How long the Virus has been in the country and whether other foreign sources could have introduced it are matters still under some debate. The fact is, like the Emerald Ash Borer and Gypsy Moth, it is here now and we need to learn how to best deal with it.
How Does HVX Spread?
Hosta Virus X spreads from plant to plant when pruning tools move plant sap from one plant to the next. It does not spread through insects and it does not spread through the soil, overhead watering, etc. That means that it is not going to spread from a single infected plant to others unless the gardener uses pruning tools without disinfecting them between plants.
A 20% bleach/water solution will kill the Virus. It will only survive for any length of time in living tissue so infected plants may simply be disposed of in the garbage or burned. To be on the safe side, do not compost infected plants.
How Does One Identify Infected Plants at a Nursery?
First, learn to ID the ways it disfigures hosta leaves so you will know if when you do see it. While no hosta cultivar has been proven to be more suseptible to the Virus than others, some of the most widely distributed cultivars are often found to be infected.
H. Sum & Substance and H. Gold Standard and cultivars derived from them including H. Striptease (a sport of Gold Standard) is often a victim of the virus when they are found in big box stores.
One should follow two guidelines when confronted by plants that are suspicious. First, assume that if a group of plants of the same cultivar contains even one suspect plant, that all plants in the group may be infected.
There are two reasons for this. The primary method of commercial reproduction today in hostas is tissue culture. If an infected mother plant was used to create the batch of plants (which easily might number a thousand or more all told) all plants from that group may eventually show signs of infection.
In other words, the tissue culture process itself does not kill a virus. A separate process is needed to do that and in the past, some TC labs simply did not go through the additional time and expense. That was especially true of TC labs operating overseas. Likewise, if an infected plant has divisions removed which are then sold, those divisions will be infected also.
There is now a reliable way to test a plant in the field to know if it is infected. Any nursery that sells hostas should possess a test kit and be willing to test suspect plants.
Secondly, understand that symptoms do not necessarily show up in all plants in the same group at the same time. Some may take as long as two years to first show symptoms. If a plant shows some mottling or discoloration which is not normal for the cultivar, it is best to pass it by.
Please be aware, however, that just because a cultivar may not be related to S&S or Gold Standard does not mean it can’t be infected. I do not believe that any hosta is immune if properly exposed to the virus.
An infected hosta will never recover from the virus. Also be aware that a few cultivars possess color patterns that suggest that they are virused but in fact are not.
Three cultivars in that category include H. Xanadu Paisley, H. Cynthia, and H. Filigree. Likewise, there are some hostas being sold which are infected. Those would include H. Kiwi Watercolours and H. Leopard Frog.
Some Common Hosta Virus X Myths
Myth: Virus X leads to the quick death of the plant. While the virus may cause some damage to the plants cells, the plant may live for a number of years with the virus.
Myth: If the symptoms disappear the following year, the plant could not have had the virus A plant with Virus X may seem to have recovered but it will be infected it’s entire life. Any “recovery” is only temporary.
Myth: One can eliminate the division of a plant that shows the virus and eliminate the virus in that plant. The entire plant is infected. The other divisions have just not begun to show the symptoms.
Conclusions
Is it fairly easy to find infected hostas of some cultivars in some nurseries?
Yes- particularly those big box stores that purchase from suppliers that get their stocks from European growers.
Will Hosta Virus X spread throughout our gardens anytime soon?
No, not at all. The virus does not spread especially easily( it cannot be spread by insects, for example) and if the basic precaution is practiced by those working with the plants of disinfecting the pruners between working with each and every plant, spread can be controlled even if there are infected plants in the garden.
Disposing of infected plants as they show up will eventually eliminate the virus from the garden assuming that more infected plants are not being introduced. With the introduction of a reliable kit that allows one to test a suspected plant on the spot, control will be much easier in the future.
From the grower’s end, most labs currently screen their hostas including mother plants and liners for a wide range of viruses so it is unlikely that they will be sources of infected plants in the future.