OCCURRENCE OF STRAWBERRY VIRUSES IN YUGOSLAVIA

A survey of strawberry virus diseases was conducted to determine their identity, occurrence and distribution in Yugoslavia. Strawberry plants were collected in the main strawberry growing areas of Yugoslavia (Cacak, Grocka, Knjazevac, Leskovac, Smederevo, Šabac and Vranje). In Grocka and Smederevo many strawberry plants showed unusual, virus -like symptoms in the field. Samples were tested by leaf grafting and subsequently for positive samples, by aphid (Chaetosiphon fragaefolii Ckll.) transmission to several Fragaria vesca and F. virginiana standard indicator clones. In addition, the samples were tested by mechanical inoculation to standard herbaceous indicator plants, by ELISA, and by double-stranded RNA (dsRNA) analysis.

Graft and aphid transmission showed that in the strawberry growing areas in Cacak, Knjazevac, Šabac, and Vranje commercial cultivars ‘Senga Sengana’ and ‘Cacanska Rana’ were most frequently infected by strawberry mottle virus (24/33 fields) and occasionally by strawberry crinkle virus (3/33 fields). In the Leskovac growing area strawberry mild yellow edge potexvirus was detected in 20% of the samples by TAS ELISA using polyclonal and monoclonal antibodies kindly supplied by Dr R.R. Martin. Detection techniques utilizing mechanical inoculation and dsRNA analysis added no additional information to that provided by leaf grafting and aphid transmission.

In Grocka and Smederevo fields most plants of the cultivars ‘Favette’, ‘Pocahontas’ and ‘Senga Sengana’ showed pronounced and unusual symptoms that were unfamiliar to us: chlorotic vein streaking accompanied by chlorotic spots and rings on leaflets. This symptomatology was reproduced by grafting to healthy F. vesca and F. virginiana plants. Over 100 plants from these two areas were sources for such symptoms by graft analysis. Identification of the putative causal agent(s) from these plants is under way.