SOME PROPERTIES OF FOUR STRAINS OF CUCUMBER MOSAIC VIRUS

Different strains of cucumber mosaic virus differ in their host range, symptoms caused, virulence towards different plants, transmissibility by aphids, dilution end-point and thermal inactivation point.
There are seasonal variations in the susceptibility of some host species; French bean is apparently immune during the summer but during the winter produces countable local lesions suitable for quantitative assays.
Different host species differ in the ease with which cucumber mosaic virus is transmitted to and from them; systemic infection in beet rarely occurs unless the virus is introduced into young tissues. Inhibitors of infectivity in sap of sugar beet and Phytolacca sp. make mechanical transmission from these to other hosts difficult; the inhibitors interfere less with the infection of hosts in which they occur than with the infection of tobacco.
Cucumber mosaic virus has a low temperature coefficient of thermal inactivation and much infectivity is destroyed by heating at temperatures below the thermal inactivation point.
Myzus persicae (Sulz.) is a more efficient vector than M. ornatus Laing which is more efficient than Macrosiphum euphorbiae (Thomas); although individual aphids can cause more than one infection, most cease to be infective in feeding periods of from one to five minutes.