European Black Currant Doubling Disease

a dangerous viral disease of the European black currant, manifested by an increase in the number of shoots with slender, elongated internodes; by the formation of leaves that are small, narrow, and flat at the base and inadequately veined; and by disruption of the flower structure. (The sepals, petals, and stamens turn into small, narrow, bright purple scales.)

Doubling disease sharply decreases the productivity of the currant bushes; when the disease is severe, it leads to infertility. The causative agent of the disease, Ribes virus 1, remains alive and hibernates in diseased plants and is transmitted by grafting and by the black currant gall mite (Eriophyes ribis). The latent period of the disease lasts from one to three years. The degree to which the disease is manifested depends on the general condition of the plants, the biological characteristics of the given variety, the level of agricultural technology, and the weather. Control measures include the creation of virus-free nurseries for the currants by culling and eliminating affected plants, the development of varieties that are more resistant to the disease (Primor’e Champion, Blestiashchaia, Zhelannaia, Memory of Michurin), and the timely control of the gall mites with acaricides.