Hosta FAQs: What can go wrong? Hosta viruses...
Dew you know
what to dew?
'Sum and Substance' with virus. Notice the "melted plastic" look of sunken tissue, and uneven discoloration (of what should be a chartreuse hosta).
'Seventh Heaven' is a streaked hosta.
'Revolution' is a speckled hosta. Not virus!
While there are lots of places online to find information about hostas (see our links), and of course a number of books you can buy for ready references, we didn't feel that there was a good place online for FAQs (Frequently Asked Questions), as experience with the American Hosta Society's Facebook page has shown. We hope you find this useful. The good stuff is at Part I. Here are FAQs on Hosta Virus X, the most serious problem of hosta commerce.
Use the little ˅ to open (and then collapse) each answer. Be sure to scroll to the bottom for instructions on keeping your garden tools clean.
'Undulata' gets "summer uglies," which are not virus.
'Gypsy Rose' with late-season mottling: suspicious but not virused.
Edge misting on a variegated form of 'Halcyon' (probably 'Autumn Frost'. Not virus!
How do I clean my tools to keep from spreading viruses?
Here’s a long and thorough answer from Chris Wilson:
Shovels: When digging up hostas, especially older/larger ones, you invariably cut into the roots. If your hostas are growing in close proximity to each other there is also the real possibility that when you dig up one plant you are cutting right through the roots of a neighboring plant. If one plant is infected and in the process of digging it you cut through a healthy plant's roots you could very quickly and easily spread the virus to the healthy plant.
So to prevent this sap transfer when digging out infected plants we suggest:
1) Dig from the side that is farthest away from any other plants, 2) Dig closer to the crown of the infected plant, and/or 3) Consider digging with a spading fork instead. These have a reduced surface area and instead of cutting out plants they pry out plants, therefore reducing the amount of cut, root to root contact as compared to shovels.
When you are done digging a known infected plant you will definitely need to thoroughly clean off your digging tools. You must remove as much of the plant sap as possible, which means scrubbing and wiping off the surface of the shovel or spading forks, preferably with disposable rags or towels. You may also want to disinfect the tools to further reduce the chance of virus remaining, especially if you were digging and cutting into a highly infected plant.
Cleaning can be done with just about any household cleaner, with the focus on removing the dirt and plant sap. If the plant sap is removed, so should the virus. Disinfecting can be done by soaking in bleach or Lysol (or other known virucidal cleaners), although it is still important that you remove the dirt and sap before soaking. Most of the known, tough to kill viruses are neutralized after a 10 minute soaking in a bleach (1 to 2%)** or Lysol solution, and although we aren't certain how long it takes to kill HVX this is probably a safe estimate, especially if you've taken steps to remove all the sap.
Again, if working with a known infected plant I recommend you thoroughly clean off the dirt and plant sap and also soak in a disinfecting solution. For everyday use it is generally accepted that if you surface clean your tools this will neutralize and eliminate most of the plant sap, and without the sap this will greatly reduce the chances of spreading the virus.
NOTE: Simply dipping your shovel or pruners in a cleaning solution for a brief moment will not provide any protection from the virus. HVX is a highly stable virus so you must work to remove and neutralize the plant sap first, then soak to disinfect.
** When mixing bleach you want a 1 to 2% solution to kill viruses. Most bleach is sold in a 3% solution, so you would mix one cup of bleach with one cup of water for a 1.5% solution. "Ultra" bleach is usually a 6% solution, so you would mix one cup of ultra bleach with three cups of water for 1.25%. When cleaning with bleach this can rust metal, so some people like to oil their tools afterwards to prevent rust. The bleach chemical also evaporates quickly from a bucket, so mix a new solution very often or put a lid over the bucket when not in use to prevent it from evaporating too quickly.
Pruners and scissors: When cutting into hosta leaves and scapes there is a large amount of plant sap transferred to these tools. Even moreso than when digging, although digging into neighboring roots transfers the virus quite easily too. Cleaning your pruners or scissors between cuts must be even more thorough than cleaning shovels.
For this job one of the easiest ways to clean is using disinfecting wipes. Clorox wipes can be used to both remove the plant sap and provide some surface disinfection.
Another method is to use a spray bottle of rubbing alcohol or Lysol and lots of paper towels. We purchase 90% rubbing alcohol and put that in a spray bottle for everyday scissor and pruner cleaning, but we also mix up a spray bottle using Lysol concentrate mixed at a very high rate and use that when working with known or possibly infected plants when we sample leaves for testing. Spray the tools down thoroughly and then wipe them off with paper towels. Soak another paper towel and cut through it with the tool to remove sap from the blades and hard to reach areas. Then soak one pair of scissors or pruners in one of these solutions while you use a second one to make the next cut.
If there is a possibility of having infected plants in your garden you may also want to avoid cutting any leaves and scapes for a while so you can keep a close eye out for possible symptoms.
Knives: Knives are often used to divide plants. Use a sharp knife to prevent getting sap into serrated edges, making them a lot easier to clean. Again, use rubbing alcohol, disinfecting wipes, or Lysol, and lots of paper towels to make sure you are cleaning thoroughly between plants. [One clever gardener relates that she purchased a dozen inexpensive steak knives at a dollar store, then uses one for each plant, tossing the used knife into a “dirty” bucket. When all the knives are dirty, she washes the whole set.]
Hands: When working with hostas don't forget to wash your hands. Washing with soap and water will help, especially when working between batches of plants such as in a nursery, then wipe with disinfecting wipes. Disposable latex gloves are also handy, just make sure you change them or wash them between batches and between divisions when dividing multiple plants.
Final notes: HVX is only spread when plants are damaged and plant sap is released. You have to cut or break an infected plant, get sap on your tools or hands, then break or cut a healthy plant and transfer the sap to through the cut. Just touching plants will not infect them but because we do so much pinching, pruning, and dividing of hostas it is very important to clean methodically between plants. While there is some suspicion that the virus could be spread by bugs or even by the mouths of deer or rabbits, this seems unlikely, although any time there is close contact between wounded plants there is the possibility of sap transfer.
If you want to read some happy stuff now, consider the FAQ Part III on starting new hostas from seed!