[About the influence of frost periods upon the serological detection of Prunus ring spot viruses in cherries (author's transl)].

During three years serological tests (latex test) were run from Novemeber till April to detect Prunus ring spot viruses in forced buds of Prunus avium L., P. avium L. var. avium, and P. cerasus L. It was found that Prunus necrotic ring spot virus (NRV) could be detected reliably during the winter in all infected trees. In contrary the detection of Prune dwarf virus (PDV) was affected by temperatures below zero. In 1971 a low percentage of positive reacting trees was pointed out after the frost periods in January and March. This result was started after the low temperatures in January 1972. The mild winter 1972/73 hardly influenced the reliability of the PDV-test.