ISHS Acta Horticulturae 94: XI International Symposium on Fruit Tree Virus Diseases
SELECTION OF VIRUS-FREE ALMOND CLONES AND INVESTIGATIONS ON PRUNUS VIRUSES IN MOROCCO |
| Authors: | H. FISCHER, G. BAUMANN |
| Abstract:
In Morocco, as shown in a survey carried out in 1977, virus infection of almond trees in zones of intense cultivation is very important, but almost unexistent in areas of extensive production in mountainous and semi-arid locations where mainly almond seedlings are grown. In graft transmission experiments all examined virus containing samples revealed to be infected by various strains of Prunus necrotic ringspot virus (NRV). Nec plus Ultra was proved to be infected with an additional virus, probably tomato black ring virus. Symptoms of peach yellow bud mosaic were found on 24-year-old trees of Texas, Nonpareil and Drake. Control measures include: in areas of intense almond production indexing of varietal collections, propagation of the selected virus-free material on imported certified rootstocks in a new isolated nursery, and distribution of budwood to authorized private nurseries for further multiplication. In areas of extensive production varietal clones adapted to the specific ecological conditions of the different growing zones are selected, indexed for virus infections and propagated on virus-free rootstocks. After 3 years observation the most promising types will be distributed as local varieties. In one orchard Prune d'Agen plum was proved to be infected with peach asteroid spot. This seems to be the first proof of the occurrence of this virus outside North America. | |
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