Susceptibility to Sharka (Plum Pox Virus) of Several Apricot Rootstocks against Dideron and Marcus Strains

Sharka, caused by Plum pox virus (PPV), is one of the most important viral diseases that affect apricot production. Although some new resistant cultivars have been recently released from breeding programs, most traditional cultivars are susceptible to PPV. Similarly, most seedling rootstocks coming from susceptible cultivars are also susceptible. Due to the high density and herbaceous stage of seedling trees in the nursery, PPV can be easily transmitted by aphis, infecting the rootstock, the grafted cultivar and finally the whole plantation. So, using resistant rootstocks could reduce the spread of sharka in Prunus orchards. In this work, the preliminary results on the resistance to PPV of 25 apricot rootstocks are reported. Rootstocks were evaluated simultaneously in France (INRA, Avignon) against PPV-Marcus and in Spain (CEBAS-CSIC, Murcia) against PPV-Dideron, by two methods: firstly, by grafting a bud of the rootstock onto an infected GF305 seedling, and secondly by grafting an infected piece of GF305 bark onto the rootstock growing on their own roots. Symptoms on leaves were observed, and ELISA was applied to check the presence or absence of PPV. Preliminary results show the susceptibility of most rootstocks studied. Only some of them were resistant, although their resistance has to be validated for some more cycles of evaluation.