WORK ON THK WHITE PINE ULISTER RUST IN MINNESOTA 13 



The owner of Nursery B below Stillwater, in which the disease 

 has probably been present for more than one year, claims that he has 

 bought only seed from European sources, and that his pines for the past 

 ten years have been of his own raising. The row of eighteen-vear- 

 old trees, upon which the blister rust was first fotmd in that locality, 

 was planted there when the nursery was first established fourteen or 

 sixteen years ago. and so far, those in a position to know where the 

 trees came from have claimed inability to state the source. The owner 

 of Nursery A at Taylors Falls, as has already been stated, unwittingly 

 brought some diseased trees from Wisconsin to his nursery in the 

 spring of 1915. So far inspections of all other nurseries in this state 

 have failed to disclose the rust. 



These facts, and the further fact that we have only found the dis- 

 ease centers thus far along the St. Croix, in no case hardlv more than 

 two miles from the river and for the most part close to the river, points 

 strongly to its introduction into this state from Wisconsin, and mani- 

 festly whatever we may do in Minnesota towards its eradication (and 

 it is not assuming to state that all has been done that could be done 

 this summer with the time and money at our disposal) will be futile, 

 unless Wisconsin authorities feel the gravity of the situation and do 

 their part in that state. 



Both infestations at Dry Creek and Pine Hollow Creek, as well 

 as that at Nursery B, have been discovered by experts in the Nursery 

 Inspection Force, employed by the State Entomologist to scout along 

 the St. Croix, covering the Minnesota side from the upper dam about 

 twelve miles above Taylors Falls to Stillwater and below, 



Wisconsin, to date, has made practically no similar survey of its 

 side of the river, but has been content to give attention to eradication 

 of pines, currants and gooseberries about Lake Waupagasset and to 

 scouting in the region close to St. Croix Falls. On June 10th the 

 Wisconsin Entomologist issued a cjuarantine notice, forbidding the 

 entrance into that state of an}' five-leafed pine. 



LIFE HISTORY OF THE WHITE PINE BLISTER RUST. 



As above intimated this parasitic disease cannot pass from pine to 

 pine, but must go to currant or gooseberry and l:)ack to pine. It can. 

 however, pass from currant to currant or currant to gooseberrv. both 

 species in the genus Ribcs, or from gooseberry to gooseberry. It is 

 transmitted from one host to another by means of tinv spores very 

 much smaller than grains of pine pollen (a spore being hardly visible 

 to the naked eye), which can be borne it is believed manv miles by 

 the wind. It occurs to us that other as:encies which mav aid in its 



