a dangerous disease of stone fruits caused by the virus Prunus virus 7. It is characterized by the formation of bands or rings of yellow or dark violet spots on the leaves, fruits, and stones. The disease, which is under internal quarantine, attacks plums, apricots, cherry plums, and peaches. It is widespread in Western Europe, Moldavia, Georgia, and the Ukraine. Manifestations of stone fruits virus appear on the leaves three to four weeks after flowering and on the fruits during the ripening period. The causative agent is transmitted by inoculum, planting stock, stool shoots, and insects (aphids). It is not transmitted by seed or soil.
Stone fruits virus lowers the yields of susceptible crops by 25 to 50 percent. Diseased fruits lose their flavor and are not fit for human consumption. Control measures include banning the export of infected planting stock; growing resistant varieties; destroying sprouts, old wild drupaceous trees, and weeds; and controlling the insect vectors of the causative agent.
Some Soviet scientists, for example, L. Ia. Tsereteli, apply the Russian name of the disease—ospa—to a noninfectious disease of citrus plants, which is manifested by sunken light brown or brown spots caused by the functional degeneration of the stomata.