Hosta Virus X - Fall 2007 Update

by Bill Meyer

 

     Well, it's Fall 2007 and I am sorry to report that the war against HVX is not going well. Two fairly distinct fronts have developed and while the war is being won on the first it is being lost badly on the second.
     In the high-priced districts both in the US and abroad, specialty retailers and the better tissue culture labs have worked together to reach a point where very little HVX is present anywhere in their stock. Few hosta specialty retailers have seen any HVX go to their customers this year and the big labs are carefully checking to the best of their ability any plants going into TC. Despite the seriousness of the HVX epidemic, I'm happy to report that your chances of getting HVX-infected hostas from hosta specialty nurseries these days is virtually nil. Better wholesalers are buying from the better labs more and more and retailers are buying from them.
     Overall, I give the hosta specialty retail industry a "10" for their efforts in getting HVX out of their nurseries. The big labs get a "10" too and if these were the only hosta producers and sellers, we would be well on our way to ending the threat this virus poses. Upscale garden centers have been improving in general, but many still offer HVX-infected hostas that they bought cheaply, so for 2007 this group gets a "6".
     Then there is the other side of the coin - the low-rent districts. Down in the nether reaches of the hosta world, where hostas are sold for rock-bottom prices, HVX is running wild. In Holland, their lower-tier growers have adopted a system of an allowable percentage (the "5% Solution") of HVX infection in their stock. Instead of trying to eliminate the disease, they are often just visually inspecting and selling any lots that have small numbers of infected plants. As HVX can take years to manifest symptoms, it is a safe bet that the number of plants in these lots with HVX is more like half or even much higher than half. Compounding the issue is their plant washing businesses which not only spread the infection to more bare-rooted plants in a batch right before shipping, but the now-infected water is reused on other batches, infecting them also if they were not already infected. These lots of disease-riddled trash are then sold to large wholesalers in the US and other countries, who in turn move them to the box stores, sell them as bare-root, or to smaller wholesalers who sell to garden centers. This whole chain of businesses is now so full of infected material that buying anything from them means you are more likely buying diseased plants than not.
     If it were not for a few educated managers and a few diligent agriculture department inspectors, I would give the lower end of the industry a complete "0". The best I can do for the efforts of the few who care is a "2", as that is about all the effect they are having on this part of the industry. The bottom-end wholesalers in the US get a "0" for their complete lack of any noticeable effort to sell disease-free plants, making even the ridiculous "5% Solution" of Dutch growers seem like an honest try. After all this time, there is no excuse for ignorance about HVX and it can be fairly assumed they know their stock is infected and care more about the money than about spreading diseases. The big Dutch wholesalers get the "2" because some are trying, but most are still selling large numbers of HVX-infected hostas with no improvement in sight. Only two years ago, the Dutch inspection service stated that they hoped to eliminate HVX from the plants being exported by 2008. Since it has apparently increased rather than decreased since that statement, it seems really unlikely. The box stores still get a "1" because of too-little education in their garden section management. Walk into any big box store and you can usually find obviously infected hostas on the shelves, although in many cases it looks like the ones with the heaviest symptoms were removed in a cheap attempt by someone to hide the infection so the plants will sell. Middle- and lower-tier garden centers share the "2", because they are mainly buying from this heavily infected chain.
     Then we have the various agriculture departments, state and federal. The USDA continues to be too busy with other more serious threats to pay much attention to HVX. At the state level, some states are doing very well in finding HVX-infected hostas and ordering them destroyed. Certain despicable wholesalers even avoid shipping infected plants to customers in those states because of fears they will be caught. Unfortunately for the rest of us, there are still too many states in which the agriculture departments seem to draw their employees from the eyesight-challenged. In states with the huge wholesale operations that sell to the box stores, it seems that inspectors are either paid off or snoozing in their cars when they are supposed to be looking at the hostas. In many other states, agriculture department visits to the box stores seem to result in the inspectors going shopping indoors and skipping the garden department. From exporter to wholesaler to retailer, no one seems to be able to see those so-obvious signs of HVX infection. Can their problem be a lack of education? It's hard to believe it is since simply typing Hosta Virus X into an internet search will get you plenty of info and pictures these days. To the state inspectors reading this ----- how about giving us a break? It can't be that hard to spot the infected plants in the box stores and at those unconcerned wholesalers who supply them. Ordinary gardeners can see it easily enough. Go look and order those infected plants destroyed! This epidemic has gone on long enough.

   GARDENER ALERT!!! This summer I think it is time to declare a moratorium on cutting flower scapes or cutting off hail- or frost-damaged foliage. These practices are just too risky in times like these. Hosta gardeners around the world must now accept the possibility that they may have an infected plant or two in their collection. There are just too many infected plants out there to feel very safe about it. I think we should all stop these and other sap spreading practices for a period of three years while we wait and check to see if any plants are showing HVX symptoms. This could make the difference between tossing a plant or two and ruining half of our collections. If you must cut hostas, you can do it safely by cleaning your tools after each plant. Use bleach or ammonia and clean them thoroughly.   

   SCIENTIFIC RESEARCH  In other news, research into HVX has been moving along. The American Hosta Society has initiated a top-shelf research program at the University of Minnesota, which is being run by Dr. Ben Lockhart. Dr. Lockhart discovered HVX and is one of the world's top plant virologists. It is still too early at this time to report results, but the program should provide some very interesting insight into the virus. This research is all volunteer-funded and will focus largely on practical concerns about how the virus is spread. The information gained from this program should be of great assistance in helping nurseries and gardeners alike in handling potentially infected hostas safely. If you would like to help fund this research, please contact AHS VP Cynthia Wilhoite at LINK. This research is being done at very favorable costs, but they still need as much as half the funding necessary to complete it.
     Other research in Korea by Ryu KH, Park MH, and Lee JS has discovered that HVX can be transmitted through seed of infected plants and that there is more than one strain of the virus. This is particularly troubling news for hybridizers as it was previously thought that it would not pass through seed. Additional research was begun in Holland but we have heard no results from it yet.
     Information about HVX from the conclusion of an earlier study by Dr. Ben Lockhart indicates that it is common for the virus to not cause visible symptoms for three or more years after infection. Reports are coming in about plants that were purchased 3-4 years ago that this year displayed symptoms for the first time. Often an infected batch of plants will only contain a small number of plants showing symptoms, but because of the long period before symptoms are expressed all plants in the batch must be considered infected. It has also been confirmed that plants that have been tissue-cultured can contain the virus if the original plant put into culture was infected. Tissue culture itself does not guarantee clean plants.  
    Although specific research has not been completed yet on how it is spread, there is good reason to assume that it cannot be spread by insects, fungi, nematodes, or pollen. Limited research has indicated it may infect plants other than hostas, but it has not been observed in other plants at this time. The primary method of infecting plants is moving fresh sap from one plant to another. There are any number of ways to do this, including the cutting of rhizomes, leaves, or scapes, lawn mowers and string trimmers, handling hail-damaged plants, keeping plants with fresh cuts in contact with each other, and possibly animals feeding on leaves. No future cure is expected, so all plants with HVX must be destroyed.

   HVX PRESENTATION DVD A new DVD presentation from Chris Wilson of Hallson Gardens, one of the leaders in the fight against HVX, is available. It has considerable information and can be purchased for $10. Half of the purchase price will be donated to the AHS Hosta Virus Fund. To get a copy, use this LINK. While you are there, be sure to check out Chris' Hosta Virus X Forum, in which he and others share their encounters with HVX. You can find it with this LINK.

What you can do - If you see hostas for sale with HVX symptoms, please assume that the seller is unaware of the problem. HVX is still new and many nursery people are still unaware of it. Inform them about the virus and point them to places where they can receive more information about it. Few real nursery operators wish to sell infected plants of any kind, and most will respond by getting rid of them. Be sure to make it clear that the plants in the batch that do not show symptoms are also likely to be infected and should also be destroyed. If they want to get plants tested, they must be sure to ask specifically if the lab has the ELISA kit to test for HVX. If they continue to sell infected plants after they have been told, and there are places that will, there are inspectors whose job it is to investigate complaints about diseased plants being sold. HVX has been a full-blown epidemic for years now and at this point the right thing to do is to report sellers who continue to sell diseased plants to the public. Enough is enough.
    If you are contacting state departments of agriculture or extension offices, be aware that many of these do not yet know about HVX. Again, point them to more information, and tell them that the USDA is aware of it and can provide more information. New symptom identification info has been added here.
    In the garden, immediately burn or place in trash to be removed from property any plants which show symptoms of HVX. If healthy-appearing plants came from batches which included plants showing symptoms discard those too rather than wait to see if symptoms appear. Watch carefully for symptoms among other plants, especially those known to have been sold with HVX infection, and discard any that show symptoms. Clean hands and tools before touching other plants after handling infected plants. Do not under any circumstances keep these plants around, even if they appear to have been "cured". Once infected, a hosta has HVX for life and can only spread it to healthy plants. This is a contagious disease that has no cure and should be treated with care. All parts of an infected plant should be considered infected with the virus and able to spread it to other plants.
   Begin practicing the habit of sterilizing tools or washing hands after getting hosta sap on them before touching other hostas. This is especially important to prevent the spread of disease when doing such chores as cutting leaves damaged by deer or hail, removing flower scapes, or other tasks which normally include spreading sap from one hosta to another. Keep string trimmers and lawn mowers away from hosta leaves.
   Inform friends and neighbors if you see plants with HVX symptoms in their gardens. Point them to more information and photos if they are not convinced. If we all pull together we may be able to get this virus stopped before our gardens are infected with it. Don't feel shy about pointing out virused hostas - many of us are already doing so.

If you have a nursery or garden center - First check the list of infected varieties, then go and see if any of these in your stock show symptoms of infection. All blocks of plants that have symptomatic individual plants should be destroyed. Hostas infected with HVX can take more than three years to show symptoms and it is not practical to test each individual plant. Some, maybe all, of the ones that do not show symptoms will also be infected. Thoroughly inspect any newly arriving stock for HVX symptoms. Even one slightly symptomatic plant means that the whole batch is infected and should be refused. If you receive infected plants from a specific source, you may wish to have other varieties from that source tested even if they appear clean. This is especially a problem with naturally divided field-grown stock. Bare root stock should be held until leafed-out and checked for symptoms. Symptoms normally appear soon after foliage expands. Be sure to specifically request that they be tested for HVX, not just general testing, because not all labs are currently testing for HVX as part of a general test.
   Blocks of the varieties above which do not show any virus symptoms but were purchased from a supplier who has sold infected plants in the last few years should be considered suspect. These should be kept separate from other varieties and from each other, and cutting any parts of these plants while still green (as opposed to dry-leaf clean-up after dormancy) should be done carefully so as to not spread sap from each batch to any other stock. Cutting roots sticking out of pots can also transmit the virus. Tools and hands should be thoroughly cleaned after handling suspect plants.
   Because the virus could already have spread, it is strongly recommended that hands and tools be cleaned after any cuts on hostas, but at minimum it should be done before moving to the next variety.

***For Hosta Sellers - The "5% Solution" vs. "Zero Tolerance"***

     Some Dutch growers and wholesalers have settled into a policy that we call the "5% Solution". While this is better than the "blindfold solution" that some low-priced US wholesalers have, it is plainly a ridiculous and bald-faced attempt to unload worthless infected stock on unsuspecting buyers. What is wrong with the "5% Solution"? The biggest problem is that it maintains a population of the virus in existing stock so that the growers are never free of it. Every year more plants infected with the virus enter the supply chain, and as hostas are very long-lived, the population of infected ones increases, as does their potential to infect healthy plants. This problem is compounded by use of visual inspections, which only catch a small percentage of HVX-infected hostas. Perhaps the "5% Solution" was really just created to cover any plants the inspectors didn't see. A lot with 5% visually symptomatic plants can be 100% infected. It is compounded yet again by power-washing techniques that spread the virus within a lot and by reusing the water spread it into other lots. Depending on the time of inspection it can also be spread further by cultivation, cleaning, and storage methods. Having any allowable percentage of HVX-infected plants is really just a thinly-disguised way to sell infected stock that would (and should) otherwise be destroyed. Buyers run the risk that inspectors will order the stock destroyed as well, and even if all funds are reimbursed (and some wholesalers selling infected stock have been shy about reimbursing) any profits are lost.
     "Zero Tolerance" should be the catchphrase for any future hosta selling. It means simply "no virus present in the plants offered as well as modern testing can determine". This is sometimes referred to as "virus indexing". Testing to insure "Zero Tolerance" will add to the cost of the hostas, but is offset by several factors that make it an attractive alternative. Unlike the "5% Solution" plants, there is no danger that the stock will be lost to a visiting inspector, customers will not return them, there are no worries about lost profits or non-reimbursement from shady sellers, and the buyer's reputation for selling healthy plants does not suffer. While "Zero Tolerance" plants are more expensive, growing awareness about HVX and other diseases will make it increasingly difficult to sell infected plants, and make no mistake about it "5% Solution" plants are really 50% or more infected by the time you receive them. Bringing infected plants into your business sets up a situation in which all your other stock can end up infected. Common nursery practices easily spread this disease.
     Ask your wholesale supplier if their plants are inspected to "Zero Tolerance" standards. While this does not guarantee that plants are completely free of any pathogens, it does mean that all efforts were made to insure that they are selling healthy plants. Don't be fooled by nonsense about allowable percentages of HVX - an infected lot is worthless garbage whatever the percentage because nobody can really tell what that percentage is.

***For Agriculture Inspectors***

     A new symptom-identification page has been added here at the HostaLibrary. It gives a good close-up look at the various symptoms of HVX in hostas, and can be copied and distributed freely. If you reading this, recommend this
page upwards in your organization for training purposes. If you see any hostas with these symptoms in a lot, you should be aware that this virus often does not cause symptoms for the first 2-3 years of infection. The presence of symptomatic plants in a lot normally indicates a much higher infection rate than is visibly indicated. As we are sure you know, plant viruses cannot be cured - they can only be spread or destroyed. As an agricultural inspector, you are a vital part of our defenses against the spread of plant viruses. Please help us spread the word about HVX, which is now one of the worst virus epidemics in ornamentals. Huge numbers of HVX-infected plants are now being sold in the US and obvious symptoms can be seen easily in box stores, garden centers, and in the fields and greenhouses of the wholesalers who supply them. You have the authority to order these infected plants destroyed if you can find them. The gardeners of America and other countries need your help in stopping this epidemic. Please inspect for HVX wherever hostas are grown and sold and order any infected lots destroyed. Without you we cannot stop HVX.

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