Glass‐house and field observations on cauli‐flower and turnip mosaic viruses in relation to the breeding for virus tolerance

Evidence is presented suggesting that mixed infections of cauliflower and turnip mosaic viruses occur more frequently than single infections in turnip crops in Canterbury. Symptom expression of cauliflower and turnip mosaic viruses was studied in the glass‐house. mainly in relation to temperature effect. These glass‐house experiments and some field observations suggest that the conventional method of selection in the field is as yet, the only one for the breeding of tolerance to virus diseases in brassicas.