Plum pox Plum pox Plum pox, also known as sharka, is the most devastating viral disease of stone fruit from the genus "Prunus". The disease is caused by the plum pox virus (PPV), and the different strains may infect a variety of stone fruit species including peaches, apricots, plums, nectarine, almonds, and sweet and tart cherries. Wild and ornamental species of "Prunus" may also become infected by some strains of the virus. The virus is transmitted by aphids and by the transfer of infected plant material to new locations. Plum pox poses no danger to consumers, but it can ruin the marketability
Cherry plum cerasifera" var "pissardii" ("P." 'Atropurpurea'). The variety 'Nigra' with black foliage and pink flowers, has gained the Royal Horticultural Society's Award of Garden Merit. "Prunus × cistena" (purple leaf sand cherry) a hybrid of "Prunus cerasifera" and "Prunus pumila", the sand cherry, also won the Award of Garden Merit. These purple-foliage forms (often called 'purple-leaf plum'), also have dark purple fruit, which make an attractive, intensely coloured jam. They can have white or pink flowers. The cultivar 'Thundercloud' has bright red foliage which darkens purple. Others, such as 'Lindsayae', have green foliage. Some kinds of purple-leaf plums are used for