PROTECTIVE MEASURES AGAINST THE VIRUS SHARKA DISEASE IN CZECHOSLOVAKIA
The main instigation to a development of experimental work with the virus diseases of fruit trees in Czechoslovakia was, however, the discovery of Sharka in the year 1952 (Blattny2 Sr.). The Sharka was then ascertained in two localities in eastern Bohemia, where several tens of diseased trees appeared.
The authorities did not pay unfortunately to these discoveries, nor to the discoveries of further particularly dangerous virus diseases - to detrimental canker of cherry and proliferation of apple (Blattny2, Blattny2, 1955), a due attention. For that reason the inspections by several research workers were made only at random, and it was proved during these inspections that the Sharka disease was spread more than originally supposed. And it was evident from this at random made investigation of Sharka, which lasted several years, that the main reservoir of its spreading are the young trees in some nurseries, affected by this Sharka disease. It was possible to ascertain the Sharka on the one hand in grafts coming either from virose grafted trees or from lateral shoots of virose young trees in the nursery, on the other hand to find it on the rootstocks. As regards these rootstocks, it was mainly the matter of so called root-shoots,