CIRCULAR No. 516 FEBRUARY 1939 



UNITED STATES DEPARTMENT OF AGRICULTURE 

 WASHINGTON, D. C. 



CONTROL OF CYCLAMEN AND BROAD MITES ON 



GERBERA 



By Floyd F. Smith, entomologist, Division of Truck Crop and Garden Insect 

 Investigations, Bureau of Entomology and Plant Quarantine 1 



CONTENTS 



Pas 



Introduction 



Culture of gerberas as a greenhouse 



crop 



Pests of gerberas and the usual con- 

 trol practices 



Injury by the mites 



Control of the broad mite 



Control of the cyclamen mite 



Page 



Plant tolerance ,__ 10 



Tolerance of gerberas to heat treat- 

 ments for mite control 10 



Tolerance of gerberas to treat- 

 ments for control of nematodes 



and certain diseases 11 



Procedure in transplanting and treat- 

 ing gerberas to prevent reinfesta- 



tion , 12 



Summary and conclusions 14 



INTRODUCTION 



The cyclamen mite (Tarsonemus pallidas Banks), has been one of 

 the most destructive pests of the gerbera or Transvaal daisy {Gerbera 

 jamesoni Bolus) when this is grown as a greenhouse floral crop. The 

 economic losses are due not only to the actual crop damage resulting 

 from the feeding of the mites but also to the money and labor wasted 

 in ineffective efforts that florists have expended toward control. The 

 broad mite (T. lotus Banks) also often causes severe damage to gerbera 

 and is sometimes associated with the cyclamen mite. 



As one phase of the investigation on the tarsonemid mites, a study 

 was made from 1933 to 1937, inclusive, of the mite injury and the 

 problem of control on gerbera with particular reference to adaptation 

 of treatments to the culture of the crop. 



CULTURE OF GERBERAS AS A GREENHOUSE CROP 



In recent years gerberas have become a widely-grown greenhouse 

 crop whose flowers are in increasing demand. The showy, daisy- 

 shaped flowers measure in some cases over 4 inches across, and the 

 colors of the rays are in many shades of yellow, orange, pink, and red. 

 The cut flowers, on 15- to 18-inch stems, retain their freshness longer 



1 The writer is indebted to F. J. Spruijt and F. S. Blanton for their cooperation in 

 conducting experimental tests and caring for treated plants in the laboratory green- 

 house at Babylon, N. Y., and to W. B. Wood for aiding in the vapor-heat treatments con- 

 ducted at Washington, D. C. and. among the several florists, to V. A. Frank. Washington, 

 D. C, to A. H. Bopp. Cumberland. Md.. and especially to C. J. Van Bourgondien. Babylon, 

 N. Y., who cooperated to the fullest extent in carrying out the experimental work at their 

 respective establishments. Thanks are due to Freeman Weiss, of the Bureau of Plant 

 Industry, for his cooperation in this work. 



104888—39 



