February, '12] SPAULDING: DANGEROUS PLANT DISEASES 77 



worst pests in southeastern Asia on citrus and other su})tropical 

 plants. This insect has in recent years been introduced with nursery 

 stock into Florida, and has already been widely distributed by one of 

 the leading nursery firms of that state. It is now known to occur 

 into several localities in Florida, and has been particularly damaging 

 on fig trees at West Palm Beach, Miami, and some other points. 



The Aleyrodes howardi, related to the white fly, has recently become 

 established on the east coast of Florida, having been brought over on 

 nursery stock from Cuba, where it seems to be a native. 



The oriental scale pest (Conchaspis angraeci) has become established 

 on figs at Miami and possibly elsewhere in Florida. 



The mango seed weevil (Cyrptorhynchus mangiferoe) has come in 

 very commonly in mango seeds imported for planting during the past 

 year. A warning circular has been issued on this insect, and it is to 

 be hoped that it has not escaped in Florida. Two important mango 

 scale insects have been brought in on shipments of trees to this country, 

 and are still in existence in Florida, and it is doubtful whether they 

 will be exterminated. 



Mr. Woglum's eastern explorations during the past year, which have 

 been so successful from the standpoint of the introduction of pre- 

 daceous enemies and parasites, have fully demonstrated that the white 

 fly is an introduced insect, its native home being the citrus region 

 lying south of the Himalayan mountains, extending from India east- 

 ward across China. In this region, Mr. Woglum not only found the 

 white fly commonly Ijut also some of the fungous enemies of this insect, 

 which are now established in Florida, and also control by parasitic and 

 predaceous enemies. 



The records above given sufficiently emphasize the risk which 

 always attends foreign plant introductions, and particularly where 

 such are new and come from regions which have been hitherto more 

 or less commerciallv isolated. 



DANGEROUS FOREIGN DISEASES LIABLE TO BE IM- 

 PORTED ON PLANTS 



By Dr. Perlet Spait;,ding, Office of Forest Pathology, Bureau of Plant Industry, 

 U. S. Department of Agriculture 



This paper will deal very largely with but two diseases from which 

 this country is in very immediate danger at present. These are the 

 white pine blister rust and the potato wart disease. Besides these will 

 be mentioned only tree diseases, as the speaker is more familiar with 



