Leaf Roll Potato Virus
Potato leaf roll virus (PLRV) is a member of the genus Polerovirus and family Luteoviridae which, in affected plants can often cause losses in yields of over 50%.
Common Signs and Symptoms of Leaf Roll (PVR)
Symptoms During Year 1: Often there are no symptoms in the first year, however there is occassionaly a rolling of upper leaves, which then become discolored, ranging from a lightish green, through yellow and finally to red, with the underside of the leaves turning purple.
Rolling is often more obvious near the base of the primary leaflets, occasionally extending to the lower leaves.
Symptoms During Year 2: Rolling of lower leaves sometimes extending to upper foliage.
Leaves are often dry and crisp with traces of brown at the edges.
Leaf roll generally causes no symptoms in the tubers.
Comon Causes and Conditions of Leaf Roll
Leaf roll, like many potato diseases and viruses, is transmitted by aphids, and is most prevalent in years when winged aphids are numerous during springtime. The leaf roll virus is persistent in the aphid, which remains infective through out its life, and may be spread over long distances. For the virus to be transmitted to the plant, aphids need to be feeding on them for a few hours.
Leaf rolling can also be caused by blackleg, stem canker or mechanical injury to the plant’s stem base.
Vulnerable / Immune Varieties
Certain potato varieties have a high resistance to leaf roll including Casanova, Midas, Sante, Saxon, Sierra, Vivaldi and Shannon.
Control of Leaf Roll
Cultural and Methods:
Use only classified seed potatoes from a reputable supplier.
If you intend to save seed from ware crop, isolate as far as possible from other potatoes – particularly those already once grown.
Your seed should be planted early with any infected plants removed quickly.
Insecticides may help to prevent spread within crop, but, more often than not, the aphids are not killed quickly enough to prevent them from introducing infection from further afield.