Evaluating the Resistance to the Plum Pox Virus of Some Apricot Tree Cultivars and Hybrids in South-Eastern Romania

In Europe, the Plum pox virus causes one of the most serious diseases of stone fruit-growing species (plum, apricot, peach, nectarine, almond and cherry) in all countries where cultivated. Romania is one of the countries in which this virus has been present for several years and where the contamination level is very high. The disease causes considerable damage, as the infected trees have few fruit, which are small, deformed, lacking in flavour, with a low content of sugar and which can neither be consumed nor used in production. In areas where the Plum pox virus is present, the cultivation of highly resistant (tolerant) genotypes is the only possibility to alleviate this problem. The purpose of the research performed in this paper was to identify varieties that are tolerant to the virus and to monitor the manner in which the resistance is transmitted to hybrid descendants. The material employed consisted of apricot tree varieties from the national collection of the Research Station for Fruit-Growing Constanþa. The presence of the Plum pox virus was determined by biological method using a GF305 wooden indicator and the serological method through the ELISA test. The varieties identified as having higher resistance to the attack of the Plum pox virus (‘Stark Early Orange’, ‘NJA 17’, and ‘Sulmona’) were used in intraspecific hybridisations for the selection of hybrids to which this characteristic was transmitted. These included: the selections ‘VT 48/45’, ‘VT 51/45’, ‘VT 47/112’ and ‘H 9/5’.