267 



-WILT" OR "CROWN-ROT" DISEASE OF 

 CARNATIONS CAUSED BY FUSARIUM SP. 



By PAUL A. VAN DER BIJL, M.A., F.L.S., 

 Mycologist, Department of Agriculture, Union of South Africa. 



(With Plates XXXVII-XL.) 



CONTENTS 



TAOE 



T . J l- ... 267 



Introduction 



A. The Disease " 



I. Symptoms 



II. Cause of the Disease: 



1. Isolation of the causal fungus . . 270 



2. Inoculation of carnations with the fungus 



in pure culture . . • .271 



3. The fungus in the tissues of the diseased 



plants ..■•••'- 



4. Humidity as a factor influencing infection. 272 



B. Growth of the Fungus in the Laboratory . . .272 



I. Growth on Various Media at 25° C. : ■ 272 



II Growth in Absence of Free Oxygen . . 277 



278 



III. Temperature Relations . . • • 



IV. Growth in Beef-broth Agar of various alkalinities 279 



V. Growth in Rice of various acidities . . 280 



VI. Experiments in the Laboratory with various Soil 



Fungicides ..-••• 



C. Field Experiments with Quicklime and Formalin . . 285 



D. Methods of Control g 



Summary 



Explanation of Plates 



Introduction. 



Sturgis 1 in 1897 described a disease in carnations known commonly 

 as "Die-back" or "Stem-rot," as due to a Fusarium sp. He first 

 observed the disease on the William Scott variety growing in the Station 



i Sturgis, Wm. C, "Preliminary Investigation on a Disease of Carnations," Ann. 

 Rep. Conn. Agric. Exp. Station, Part m, 1897, pp. 175-181. 



