CARNATION WILT DISEASES AND THEIR 

 CONTROL 



By E. F. Guba, Research Professor of Botanyi 



INTRODUCTION 



The culture of carnations in greenhouses represents a large industry in 

 Massachusetts and nearby adjoining areas. This industry is concentrated within 

 a radius of 40 miles of Boston. Each year approximately 26,000,000 or more 

 carnation cut flowers are produced in this area. The flowers are shipped to 

 markets throughout the eastern half of the United States, as far south as Miami, 

 Florida, and as far west as Chicago and St. Louis, and to nearby wholesale 

 markets. In addition a large number of flowers is retailed on the growers' prem- 

 ises, for which no accurate production figures are available. The average 

 gross return to the grower over several years prior to the war period has been 

 about 334 cents per flower. The climate and soil in New England seem especially 

 well adapted to carnation culture and to the production of flowers with desirable 

 keeping and shipping qualities. 



The industry has experienced large losses from carnation diseases, notably 

 from blight caused by the fungus Alternaria dianthi and branch rot caused by 

 Fusarium dianthi, and other diseases collectively manifesting the common symp- 

 tom of wilt. The occurrence of the blight disease in epidemic proportions an- 

 nually over several years, and the importance of the carnation cut flower industry 

 in Massachusetts, have off'ered adequate justification for this study and for a 

 broad treatment of the general subject of carnation diseases. 



The subject matter of this paper has been arranged essentially into sections 

 conforming to the various stages or practices in carnation culture. Information 

 is presented regarding desirable treatments and cultural methods in relation to 

 the control of carnation wilt diseases. The contributions of earlier investigators 

 are freely off'ered. This procedure has seemed desirable in view of an extensive 

 literature, especially from the United States and England, with which our grow- 

 ers are not familiar. 



CLASSIFICATION OF CARNATION WILT DISEASES IN MASSACHUSETTS 



The fungous diseases of greatest consequence encountered in the culture of 

 carnations in Massachusetts are spot, blight, and canker caused by Alternaria 

 dianthi Stev. & Hall.; root and crown rot caused by Fusarium avenaceum (Fr.) 

 Sacc, Fusarium culmorum (W. G. Smith) Sacc, and other Fusarium species; 

 branch rot or Fusarium wilt caused by Fusarium dianthi Prill. & Delacr.; and 

 stem rot caused by Rhizoctonia solani Kiihn. Symptoms of diseased carnation 

 plants associated with these pathogenic organisms are wilting, yellowing, brown- 

 ing, and death of the branches or the entire plant. Distinctive and characteristic 

 manifestations of disease are peculiar to each causal organism. The principal 

 and most distinctive symptoms are expressed by various appropriate common 

 names. Some common names have been employed rather loosely or without 

 the scientific Latin counterpart, and this has led to some confusion in the litera- 

 ture. 



^The author appreciates gratefully the generous cooperation and goodwill of the car- 

 nation growers of Massachusetts and the New England Carnation Growers' Association in his 

 service to their industry. 



