Infected plants must go
A blotchy, mottled coloration that varies from leaf to leaf is a symptom of hosta virus X.
If you think you have a hosta with the virus, discard it, because there are no chemicals to treat plant viruses. Even if later flushes of leaves look normal on plants that showed symptoms earlier in the season, the plant still has the virus. Virus testing is expensive, but if you have a valuable plant with symptoms of HVX and you want confirmation, send a leaf sample to AGDIA, Inc., a disease-testing service (for more information, visit www.agdia.com or call 800-622-4342).
Once you have removed an infected hosta from your garden, you may plant another in the same spot because the virus is in a plant, not the soil. You may want to wait a few weeks, though, so that root fragments from the infected plant you removed have had time to start decomposing. HVX can't survive long without living cells.