Severity of symptoms of European stone fruit yellows on different apricot varieties

Apricot is an important fruit crop in Hungary. There are large growing areas consisted of orchards of different sizes. These orchards are highly affected by a disease complex the so cold apoplexy with its characteristic symptoms. In this study, the effect of rootstocks and scion varieties on the severity of symptoms was investigated in an apricot orchard near Budapest. Symptoms were assessed in autumn at their most characteristic appearance on the combinations of 5 different scion varieties and 3 different rootstocks in 3 consecutive growing seasons. According to the results of the assessments in most cases, symptoms proved to be more frequent and stronger on trees grown on wild apricot rootstock than on plum intergrafted or myrobalan rootstocks. The variety Mandulakajszi proved to be consistently the least affected variety particularly on plum intergrafted rootstocks. Severity of symptoms observed on other investigated varieties deviated depending on the different rootstocks and growing seasons. To reduce the effect of growing seasons monitoring should be continued. &nbsp