hellebore black death Helleborus net necrosis           Family: Carlavirus

Common name: hellebore black death
Host plant: Helleborus spp.
Life cycle:
            Spring: HeNNV attacks new growth
            Summer: black streaks and stunted growth
            Fall:
            Winter:
Type: viral disease transmitted by the hellebore aphid, Macrosiphum hellebori

Description: A viral disease, Helleborus net necrosis virus or HeNNV for short, which infects plants in early to mid-spring. Symptoms appear as distortions on new foliage, causing the plant to look stunted. Typically, patterns of vein-clearing (streaks of lighter leaf colour along the veins) will become evident, followed by discoloration and darkening into distinct black streaks, or lines. The damage will become progressively worse as spring advances. Black streaks will eventually develop on the stems and extend onto the sepals and carpels.

 

Special Notes: Hellebore Black Death has been known to develop a pattern of rings, rather than streaks, which can confuse a gardener into thinking their plant is afflicted with the much less deadly disease, black spot.

Early speculation leans towards this virus being carried and transmitted by the hellebore aphid, Macrosiphum hellebori.


 Remedial Action: Remove all leaves which are showing black streaking or black spots and place in garbage. Do not compost! Check plants carefully for aphids, as this is how scientists believe the virus is being transmitted. Treat thoroughly if aphids are present.

If the plant is deteriorating with progressing black streaking and overall stunted growth, dig up plant and place in garbage. There is no none cure for Hellebore Black Death at this time.

 

Posted on January 24, 2018