POMONA COLLEGE JOURNAL 



of ECONOMIC BOTANY 



Volume II SEPTEMBER 1912 Number 3 



A Stem Rot Disease of Carnations Due to 

 a Species of Fusarium* 



CLAYTON J. WIGHT 



INTRODUCTION 



In August, 1911, Mr, James McDonald of Alameda sent to the University 

 Laboratory of Plant Pathology a diseased carnation plant {Dianthus caryo- 

 phyllus L.) and reported that his plants were dying from some unknown cause. 

 The stem of this diseased plant was placed in a box of moist sand and long 

 curved spores of the Fusarium type developed upon it. This experiment 

 formed the incentive which led to the investigation of the stem rot disease 

 among the carnation growers in the vicinity of Oakland, Berkeley, and Rich- 

 mond, and to a review of the literature upon the subject. The studies described 

 in this paper have been carried on for the purpose of detennining the nature 

 of the disease, its extent, its remedy, and the relation of the disease organism 

 to Fusarium oxysporum, a fungus which causes the dry rot of potatoes and 

 is so fully described by Erwin F. Smith and Deane B. Swingle in Bulletin No. 

 55, of the Bureau of Plant Industry. 



HISTORY OF THE "STEM ROT" DISEASE OF CARNATIONS 

 The carnation stem rot disease has been known among growers for many 

 years, but it was not brought to the attention of plant pathologists until the 

 latter part of the nineties, and comparatively little has been written about it. 

 In 1897 Wm, C, Sturgis, of the Connecticut Agricultural Experiment 

 Station, observed the disease attacking the variety William Scott, which 

 appeared to be more susceptible than others. He stated that the disease 

 appeared first as a yellowing of the lower leaves and spread until it involved 

 the whole plant. The cause of the disease was determined to be due to a 

 species of Fusarium which gains access to the tissues at, or just below, the 

 surface of the soil. The mycelium accumulated in the water ducts of the stem, 

 thus preventing the free transfer of water. It was thought probable that the 



♦Prepared from Thesis submitted in partial fulfillment of the requirements for 

 the Degree of Bachelor of Science, University of California, May, 1912. The original 

 thesis is preserved in the Department of Agriculture, University of California, and 

 contains two colored plates and other illustrations not included here. 



