A BACTERIAL ROT DISEASE OF SAFFRONS

Abstract

Bacterial rot of soffron is a typical disease of the tubers, roots, sheaths, foliages and flower stalks. The worst damage is due to the tuber lesions. The primary detection of the disease in Japan is at 1909 and the disease has recently become most serious and widespread, The lesion is destructive when successive cultivation is kept on and also when the diseased tubers are transplanted. The causal organism is a peritrichiate bacterium which is described herein as Bacillus croci, n. sp. It grows readily on various culture media, producing white, round colonies. It produces acid but no gas with carbohydrates and is very resistant to high temperatures and tolerable to a high acidity. Isolution of the organism has been accomplished repeatedly from rot-tuber or decayed sheath. Inoculations of healthy tubers or sheaths with pure cultures produce a rapid, soft decay of sheaths and a tuber-rot. The organism remains on the rot part of saffron plant and in the infected soil. The disease is mainly disseminated by transplanting the disease tubers. Although no means of control has been yet worked out, selection of healthy tubers and disinfection of the seed tubers in saturated lime water for half an hour seem to be advisable.