Cherry plum pox potyvirus:: Receptivity of cherry trees and hosts of the sour cherry strain

In order to study the capacity of cherry to replicate plum pox virus (PW), we performed two different types of experiments. In the first range of experiments, we double chip-budded PPV isolates D-B3y, M-945 and El Amar from GF 305 onto these following rootstocks: P. avium F12-1, P. cerasus Edabriz and P. mahaleb Pontaleb. Seventy-five percent of these rootstocks were grafted at the same time, in March 1995, with commercial varieties -P. avium grafted on F12-1 and Pontaleb, P. cerasus grafted on Edabriz-. Onto the 25% remaining rootstocks, we kept regrowths close to peach inocula. In June 1995, these regrowths and the young shoots from budded varieties were indexed by chip-budding onto GF 305 peach seedlings to detect PPV. We noted the following results (positive/tested plants): P. avium 2+/45, P. cerasus 6+/30, P. mahaleb 0/15. These were not related to the isolate, D, M or El Amar. P. cerasus showed a better receptivity than P. avium. After 2 months at 5 degrees C for a dormant period, cherry trees were grown in a greenhouse and indexed on GF 305 in October 1995. Results were as follows: P. avium 0/40, P. cerasus 0/30, P. mahaleb 0/15. The different strains were not replicated 7 months after inoculation. In the second range of trials, we inoculated the strain SoC-Moldova sour cherry- on a host range in a greenhouse (under an insect proof screen), in January 1996. We observed the Prunus reactions until the beginning of 1997. On February 20th of 1997, we noted: (i) symptom remission or weak reactions on hybrid almond x peach, P. armeniaca, P. avium, P. cerasus, P. davidiana, P. laurocerasus, P. mahaleb, P. mariana, P. persica. These plants have little aptitude to replicate the strain So-C under our greenhouse climate conditions; (ii) clear symptoms on P. serrulata which seems to be a good host for the SoC strain; (iii) very severe necrosis, followed by decline on P. insititia and P. domestica which appear very sensitive.