THE DETECTION OF LATENT VIRUSES AND MYCOPLASMA-LIKE ORGANISMS IN PEAR

In indexing of pear varieties with the indicators “Kirchensaller Mostbirne”, “Beurré Hardy”, “William’s Christ”, “Clapp’s Favourite”, “Lord Lambourne”, “Virginia Crab K 6”, “Spy 227” and Pyrus betulaefolia 27 trees of 22 varieties proved to be free from graft-transmissible diseases as ring pattern mosaic, vein yellows, blister canker, rough bark, bark split, bark necrosis, stony pit, rubbery wood, stem pitting, stem grooving, Spy epinasty and decline and an apple latent virus indicated by Pyrus betulaefolia.

Supplementary tests were performed by using Pyronia veitchii, quince C 7/1, “Beurré Hardy” and the oriental species Pyrus ussuriensis and Pyrus serotina for detection of latent viruses and mycoplasma-like organisms in pear.

8 trees of 7 varieties induced dents and grooves in the stem and larger branches of Pyronia veitchii without causing symptoms on the leaves.

Test plants of quince C 7/1 inoculated by the same sources were moderately stunted (except 1 source). In some cases grooves and dents developed on the stem.
No leaf symptoms appeared.

Some pear trees, which had induced symptoms in Pyronia veitchii and quince C 7/1, and other ones, which had not induced symptoms similar to pear decline on the indicators “Beurré Hardy”, Pyrus ussuriensis and Pyrus serotina.

There seems to be no identity between the viruses/mycoplasma-like organisms, which caused symptoms on Pyronia veitchii, quince C 7/1 and on the indicators for pear decline.

XI International Symposium on Fruit Tree Virus Diseases

G. HAMDORF

https://doi.org/10.17660/ActaHortic.1981.94.22