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Clover Yellow Mosaic Virus from Apple Trees with Leaf Pucker Disease. Maurice F. Welsh, Plant Pathologist, Research Station, Canada Department of Agriculture, Summerland, British Columbia; R. Stace-Smith(2), and E. Brennan(3). (2)Plant Pathologist, Research Station, Canada Department of Agriculture, 6660 N.W. Marine Drive, Vancouver 8, British Columbia; (3)Technician, Research Station, Canada Department of Agriculture, Summerland, British Columbia. Phytopathology 63:50-57. Accepted for publication 17 July 1972. DOI: 10.1094/Phyto-63-50.

A virus sap-transmitted from apple induced symptoms on herbaceous plants that differ from those induced by other viruses reported to infect apple. The virus has been isolated from cambial and/or fruit tissues, but not from petal or leaf tissues of apple trees displaying leaf pucker disease symptoms. In clarified Chenopodium quinoa sap, the virus has a dilution end point of 10⁸ and thermal inactivation point (10 min) at 52 C, and retains infectivity at 18-20 C for 9 weeks. Particle dimensions by electron microscopy are 590 ± 10 nm × 13.5 nm. Purified virus preparations have a sedimentation coefficient of 122 S, an absorption peak at 263-265 nm, and minimum absorption at 245 nm. Antisera with titers to 1:3,200 were obtained. No serological relationship could be demonstrated with other rod-shaped viruses from tree fruits or with 14 rod-shaped viruses from other hosts. However, the apple virus proved to be serologically indistinguishable from clover yellow mosaic virus (CYMV). It has a similar host range and induces symptoms on clover that resemble those of CYMV.