232 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



causing this disease has an alternate stage of growth upon the leaves 

 of wild and cultivated currants and gooseberries, that is, the genus 

 Ribes. Ever since 1909, when the disease was first found in this 

 country on pines, an effort has been made to eradicate this disease 

 from this country because of the very serious danger with which it 

 threatens our white pines. From 1909 to 1914, inclusive, there were 

 eleven distinct cases where the disease spread from pines to neighbor- 

 ing Ribes, thus showing very emphatically the extreme danger of its 

 becoming permanently established in this country. In some of these 

 cases the disease also spread back to the neighboring pines from the 

 infected Ribes, thus completing the entire life cycle of the parasite. In 

 1915, owing to the prolonged wet weather and accompanying winds, 

 there were twelve such outbreaks of this disease. At present we have 

 then a number of areas varying in size from a few acres up to an area 

 in one case of some five hundred square miles, where the disease has 

 spread upon Ribes and threatens to become permanently established. 

 The disease cannot spread in any locahty unless both kinds of hosts 

 are present in that locality, that is, the removal of either one stops 

 the spread of the disease. 



The foresters of the white pine region have become thoroughly 

 alarmed concerning the situation. It seems to be entirely practical 

 to stop the spread of this disease in these infected localities by the mere 

 removal of wild and cultivated Ribes within them and for some distance 

 outside. This appears to be a far more practical procedure than that 

 of the removal of gipsy and brow^n tail moths from trees up to 80 

 or 90 feet in height, which is being performed every year now in some 

 sections. 



In order to carry on this removal of Ribes, however, it is absolutely 

 necessary that the horticultural inspectors of the various states shall 

 have absolute power with which to compel uniform action on the part 

 of the owners, if such uniform action cannot be otherwise secured. 

 This matter is one which is sure to come to you within a very few years, 

 and is even now staring some in the face. 



Another matter which would go far toward reducing the danger 

 from this disease is the quarantine of black currant, Ribes nigrum, so 

 that it cannot be shipped from state to state. Such quarantine power 

 also is important in preventing the shipment of white pines from one 

 state to another. These two things every state horticultural inspector 

 ought to try to have incorporated in his law, as he is sure sooner or 

 later to find them necessary to his carrjdng on efficient work. 



