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Hostas and HVX virus

Hosta problem could be a virus, not bugs

By: Sandy Feather 2007
Penn State Extension


Q. I have a large shade garden and hostas are the workhorses in it. I am very concerned about the new hosta virus I have been hearing about. Can you tell me more about it?

A. You are referring to hosta virus X (HVX). It was first reported in 1996 at the University of Minnesota. Symptoms vary by cultivar, and the length of time they have been infected. These can include stunting, mottling that follows the leaf veins, mosaic patterns, ringspots, puckering, twisting and/or blotches. Mottling may appear to bleed out from the veins into the surrounding leaf tissue. Some cultivars exhibit brown, dead spots.  In some cases, entire leaves die.


Progression of the Virus

Newly infected plants often exhibit no symptoms at all, but those plants can transmit the virus to healthy hostas if they come into contact with sap from the infected hosta. It can take three or more years for some plants to show symptoms. To compound the difficulty in determining if any of your plants are infected, certain cultivars do not show distinctive symptoms at all.

hosta plants


Trojan Horse Viruses

Given that hosta lovers are always on the lookout for new cultivars with distinctive leaf colors and patterns, HVX is a cruel joke. Many hobbyists, as well as professional plant breeders, collect seed and grow the resulting seedlings in hopes of finding a hot new hosta. As a matter of fact, before HVX was identified, infected plants with unique leaf colors and patterns were thought to be new cultivars, given names, and introduced to the marketplace. These include 'Breakdance,' 'Eternal Father,' 'Kiwi Watercolours,' Leopard Frog,' 'Lunacy,' and 'Parkish Gold.' Although they have been taken off the market, some of those cultivars might still be found in people's gardens. All plants with these names are thought to be infected and should be removed and destroyed.


Diseases Spread

HVX is transmitted by spreading the sap of infected hostas to healthy ones. The virus can be spread by inadvertently hitting infected hostas with lawn mowers or string trimmers, by deadheading or pruning off dead leaves with pruning shears, on your hands, by animals feeding on hostas, and by propagating infected plants. There is currently no evidence that insect feeding spreads HVX.

Variegated Hosta
Variegated Hosta

There is no cure for HVX, as is true for all virus diseases. Scout your garden regularly and removed any hosta that shows suspicious symptoms promptly. Burn it or tie it up securely in a trash bag for collection - never toss it on the compost pile. Since viruses are systemic, it is not enough to cut off dead or funny-looking leaves. Thoroughly wash and sterilize pruning tools that you use on your hostas before moving from one plant to the next. Clean and sterilize shovels, too, after using them to dig out suspect plants. After completely cleaning any soil or sap off, dip the pruners in isopropyl alcohol and allow them to air dry, or dip them into a solution of one part Clorox to nine parts water. Dry tools after the Clorox dip to keep them from rusting.

 


What to Avoid

Shop for new hostas carefully, and avoid anything that does not look normal. Even though some hostas have mottling patterns not caused by virus, these will be spread evenly over the leaf, rather than following the veins, as is true if they are infected. Cultivars that have mottled leaves that are not known to be the result of HVX include 'Cynthia,' 'Laella,' 'Kiwi Forest,' 'Wild Bill, and ' Xanadu Paisley.' Be cautious about accepting unusual-looking hostas from friends or at plant swaps. Introduce new hostas to your garden with care. If possible, isolate them from your established beds and observe them for at least a year before planting them in your garden.

mixture of various hostas

The only sure way to confirm that a suspicious looking hosta is infected with HVX is by virus indexing through a certified laboratory. This can be expensive, and is really meant for professional growers rather than home gardeners. John Peplinski, the director of Penn State University's Buckhout Laboratory, has not seen any probable HVX samples come through his lab to date. (Penn State's Disease Diagnostic Lab does not perform virus indexing).


Is the Soil OK?

There is no evidence that HVX survives in soil, so you can replant the area with clean hostas after you a sure that all of the infected plant's roots have decomposed. The virus is limited to hostas and is not known infect other species of plants. Although all hostas should be considered susceptible, several are reported to be resistant to HVX, including 'Blue Angel,' 'Color Glory,' 'Frances Williams,' 'Bressingham Blue,' 'Frosted Jade,' and 'Love Pat.'

There are excellent photographs of HVX symptoms on a number of websites, including Michigan State University.

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