a1 Lecturer in Botany, University College of Wales, Aberystwyth.
Of recent years a disease of root-crops known to farmers in North Wales is one in which the heart or core of the root is converted into a soft putrid mass but which leaves the rind and mature foliage intact. The disease is prone to appear on land treated with lime as a preventive against the roots being attacked by Plasmodiophora brassicae or when the land has received a heavy dressing of nitrogenous fertilizers. It is common knowledge that nitrogenous manures have a tendency to force the crop and so produce watery, sappy roots which easily fall prey to disease. Recently it was brought to the writer's notice by one of the County Organizers for Agriculture in Wales that some of the farmers in his area were strongly disinclined to lime the land for root-crops because this treatment was favourable to the appearance of “soft-rot.” There is probably some modicum of truth in this contention, for as will be seen below, the writer in the investigation of the present disease found that the organism isolated refused to grow on any media which were not neutral or alkaline. The writer observed and investigated this disease on a crop of white turnips grown on the farm of the University College of North Wales and the land here had received a dressing of nitrate of soda. A casual glance at the crop did not show anything unusual, in fact judging from the amount of green foliage the crop looked very healthy. Closer examination however showed that the very young leaves at the centre of the crown had been destroyed thus forming a tiny wound into which one could push a probe without obstruction to the depth of some three or four inches. The fully expanded leaves very effectively concealed the wound and the disease seemed evidently confined to the internal tissues leaving the foliage and rind quite firm even up to time of harvesting the crop. Indeed the extent of damage was only fully revealed at the time of lifting when the harvester's knife lopped off the foliage only to discover that the roots were bad.
(Received June 13 1922)