6 



CIRCULAR 516, U. S. DEPT. OF AGRICULTURE 



by applications of sprays or dusts. Such f umigants as calcium cyanide, 

 nicotine preparations, and naphthalene have not proved successful as 

 control material because of the inacessibility of the cyclamen mite and 

 its great resistance to these chemicals. Because the desirable va- 

 rieties of gerberas are propagated vegetatively (by division of crowns), 

 the infested plants are not discarded but are carried from year to year 

 and are not freed of the cyclamen mite in the regular handling of 

 the crop. 



HOT-WATER TREATMENT 



On the basis of experiments with heat treatments as a control for 

 the cyclamen mite, 3 gerbera growers were advised to immerse their 



Figure 4. — The cyclamen mite in its several stages as it occurs in crevices among 



flower parts of gerbera 



plants in water at 110° F. for 15 or 20 minutes, but in two instances 

 reports of incomplete control were received. Investigations of the 

 methods employed in each case indicated that subsequent to treatment 

 the plants were satisfactorily handled to prevent reinfestation, but in 

 the treatment itself the plants were closely packed in a slatted crate 

 such as is used for shipping lily bulbs, for immersion in water already 

 heated by steam to 111° F. at the beginning of treatment. It appeared 

 that the closely packed foliage would not permit rapid enough pene- 

 tration of hot water to kill the mites during the period allowed. 



3 Smith, Floyd F. the cyclamen mite and the broad mite and their control. 

 U. S. Dept. Agr. Cir. 301, 14 pp., illus. 1933. 



