Note on “Plasmodiophora brassicæ”

Abstract

ALTHOUGH it is well known that Plasmodiophora brassicae attacks the great majority of cruciferous plants, yet no instance of the common Shepherd's purse (Capsella bursa-pastoris, D.C.) being attacked is recorded in this country. Thus Massee (Proc. Roy. Soc., vol. lvii.) quotes the Shepherd's purse as being reported by Halsted to be attacked in America, but says “It has not been observed to be diseased in this country, although one of our commonest weeds.” During the past summer my attention was drawn to some plants of Capsella with swollen roots, growing in a sandy field near Coventry, on land upon which crops of swedes and turnips were grown in the usual rotation, and I had no difficulty in finding several additional specimens. These roots, on examination, were found to have the characteristic plasmodium in their cells. The Shepherd's purse must now be numbered among the plants in this country which provide a home for Plasmodiophora, and probably help it to maintain its existence in the ground from year to year, thus proving a possible source of injury to cruciferous crops.