CONTROL OF CYCLAMEN AND BROAD MITES ON GERBERA 5 



by the cyclamen mite is usually less extensive and less conspicuous 

 on the foliage. The cyclamen mite breeds more slowly than the broad 

 mite and in all observed instances has been less abundant on gerbera. 



The cyclamen mite also moves to the young flower buds and feeds 

 beneath the bracts and on the young rays, preventing the normal 

 expansion of the latter. It makes little difference whether few or 

 many rays on a flower are distorted or stunted by this mite (fig. 3), 

 for the destruction of only one or two rays renders the flower unsalable 

 or of low market value. 



A comparison of the injury by the two mites indicates that the 

 broad mite causes more serious injury to the whole plant, particularly 

 in warm greenhouses from late in the spring until earty in the fall. 

 During the cooler parts of the year it breeds very slowly and so causes 

 little or no damage during the winter. On the other hand the 

 cyclamen mite breeds during the cooler parts of the year and causes 

 damage throughout the flowering season of the gerbera. The presence 

 of the cyclamen mite is usually not detected until the injury appears 

 on the flower. Since this is the marketable part of the gerbera crop, 

 the cyclamen mite is undoubtedly the more serious economically. It 

 is also the more serious pest because the usual practices fail to control it. 



CONTROL OF THE BROAD MITE 



Experiments 2 have shown that the broad mite is readily killed by 

 dusting the plants with finely ground flowers of sulphur or colloidal 

 sulphur, or with prepared dusts containing as little as 25 percent of 

 sulphur and as much as 75 percent of inert carrier. This mite is also 

 killed by certain other methods, including fumigations with calcium 

 cyanide or naphthalene, and by the heat treatment which is used for 

 control of the cyclamen mite. These other methods are not recom- 

 mended as a control measure for the broad mite on gerberas because 

 the Ioav cost and effectiveness of sulphur make that the more economical 

 material and because of the high tolerance of the host to sulphur dust. 



Although the mites in either the egg stage or the quiescent stage 

 ("pupae") are only slightly affected by sulphur, the larvae or adults 

 emerging from these stages succumb shortly if sulphur is still present 

 on the plants. Therefore only one dusting with sulphur, if not syr- 

 inged off the plant within 4 or 5 days, will ordinarily destroy an in- 

 festation. In practical tests on gerbera, however, two or three appli- 

 cations were usually made at 5-day intervals to insure that all infested 

 parts were reached by the dust or its vapors and the infestation de- 

 stroyed. Where infestations occur, applications repeated two or three 

 times are recommended as a general greenhouse practice. 



CONTROL OF THE CYCLAMEN MITE 



Florists generally recognize the presence of the cyclamen mite by 

 its injury, but the mites (fig. 4) secrete themselves in the many crevices 

 in the crown, young foliage, and flower parts, and few are reached 



2 Smith, Floyd F. control experiments on certain tarsonemus mites on ornamen- 

 tals. Jour. Eeon. Ent. 28 : 91-98. 1935. 



