DATA ON VIRUS DISEASE OF PLUM TREES IN ROMANIA

In Romania, as well as in other countries of the Balkan Peninsula, plum-pox is considered as the most important virus disease of fruit trees, due to its transmission by aphids and to its detrimental effect both on yield quantity and quality.

In our country, symptoms similar to plum-pox were described in 1922 by D.I.Stefanescu, under the name of "Degenerescence of the d'Agen plums", the disease being later referred to by Savulescu et al. (1944) as "Plum blister". The Romanian corresponding name for plum-pox, "varsatul prunului", was introduced later in our speciality literature (Pop, 1958).

With a view to elaborating differential preventive measures for each zone, stress was laid on the determination of the infection degree of plum varieties grown in different regions of the country. The results of the numerous observations, carried out during several years in nurseries and plantationd, by many researchers, show that plum pox has a high economic importance in some districts situated in the south-western part of the country and in Moldavia as well as in districts of Arges, Vîlcea, Dîmbovita and Prahova in Wallachia.

In general, he infection degree is greater in regions in which fruit growing is most developed and intensive, the variety assortment is richer and the exchange of planting material more frequent. In Transylvania and in the districts situated in the western and north-western parts of the country the virus is less widespread. In these regions the disease does not occur on local varieties propagated by suckers directly by the growers; it occurs, however, in a low percentage in plantations and nurseries, in which the material used in their establishment was obtained from nurseries, coming from other zone^s