15 December 1998
Detecting mosaic virus in the soil
HOW can I tell if my soil is infected by mosaic virus when the crop is not yet showing any symptoms? And what can be done to cure the virus?
Dr Mike Adams, IACR-Rothamsted, Harpenden, Hertfordshire
You wouldnt normally expect to find virus except where you see symptoms.
The virus remains in the roots of plants at very low levels until the spring, when it emerges as leaf symptoms. The polymyxae fungus, which acts as a host for the BYMV virus, is widespread but does not carry the virus everywhere.
It might be useful to have some sort of pre-planting soil test which would tell you whether you have the virus in the field. That is something we have in mind but are unable to do at present.
As part of the research programme at Rothamsted, we welcome samples of infected plants from growers, which will help us in establishing the extent of BYMV infection and its new Race 2 strain.
While it is possible grow barley varieties with resistance to the original, more common strain, there is nothing a grower can do agronomically to offset Race 2.