Hosta Virus X
Hosta, especially 'Gold Standard', 'Striptease', and 'Sum and Substance', but other common varieties are being reported infected in large numbers. While this disease does not kill plants, its primary danger lies in its proven ability to spread prolifically. Home gardeners and some nurseries propagate hostas by dividing existing plants. This means of propagation and failure to recognize HVX symptoms on many varieties have led to the rapid spread of the virus throughout the country.
Hosta Virus X affects different hosta cultivars in different ways, so it is impossible to give a definitive description of symptoms. The most common visual symptom is blue or green markings on a light colored leaf. These markings usually follow the leaf veins and bleed out into surrounding tissue giving the plant a mottled appearance. The tissue often appears lumpy, puckered, and of different thickness or texture that normally colored tissue. Less common symptoms include dried, brown spots and twisted, deformed leaves. It may be difficult to detect off colored mottling on dark, solid colored leaves. Some green tissue will show lighter colored mottling along the veins, but it is often not as pronounced as the markings on gold tissue. Some infected plants will not develop symptoms for three to four years after becoming infected.
Growers should submit plants with suspicious symptoms to the Plant Disease & Insect Diagnostic Lab for ELISA antibody testing. While ELISA tests for Hosta virus X are not 100 percent accurate, they represent the most practical testing procedure currently available and will detect the virus in most infected plants.
There is no practical cure for this virus. The best way to prevent Hosta Virus X is to not grow infected plants. This virus is transmitted primarily through cutting the plants. Contact of the infected plant's sap with sap of a healthy plant will infect the new plant. This can happen whenever cuts are made and the instruments or hands are not disinfected afterwards. Tools should be dipped in 10 percent bleach solution and hands washed thoroughly between working on each plant. Plants in pots may be simply disposed of or burned. Plants in the ground should be dug carefully as to get as many roots as possible, and the spot should not be replanted until any remaining roots have died and rotted away. Always avoid strangely spotted or mottled plants you find at nurseries. Not all infected plants show visible symptoms, though, so if one plant in a group shows symptoms do not buy healthy-looking plants in the same group. If one has it, it is very possible some, and maybe all, of the others do.