WORK ON THE WHITE PINE BLISTER RUST IN MINNESOTA 11 



became established. It is now (October, 1916) reported as occurring 

 in New Jersey also. To prevent further introduction of the disease into 

 this country the Federal Horticuhural Board has forbidden (May 21, 

 1913) the importation of all five-leaf pines. This quarantine super- 

 seded that of September 16, 1912. It did not, however, quarantine any 

 of the above infected states from which pines had been freely shipped, 

 and currants and gooseberries are still allowed to enter the United 

 States from Europe and other foreign countries. The entrance of these 

 canes is doubtless permitted, because it has yet to be definitely estab- 

 lished that the rust spores pass the winter upon them. 



LOCALITIES IN MINNESOTA WHERE WHITE PINE 

 BLISTER RUST IS KNOWN TO OCCUR. 



In May a professor in ]\Iacalester College, St. Paul, Minnesota, 

 submitted to the Experimental Station, a portion of a diseased pine 

 coming from his farm in Polk County, Wisconsin. This was at once 

 determined by our Plant Pathologist to be White Pine Blister Rust. 

 Incident to a visit in the latter part of May to St. Croix Falls, Wiscon- 

 sin, upon the part of members of the Plant Pathology Division and a 

 member of the Nursery Inspection force, the disease was also found 

 in a Minnesota nursery (which, to avoid personal reference we will 

 designate as "Nursery A"), close to the St. Croix River, the proprietor 

 of which had in the spring of 1915 obtained white pine trees at an old 

 nursery in St. Croix Falls, Wis. This last named nursery had pur- 

 chased these pines in one of two shipments, or in two shipments of trees 

 from Germany, coming thru an Illinois firm in 1908-09. 



Later, Jwly 14th, two experts employed by the State Entomologist 

 scouting for the disease along the banks of the St. Croix discovered 

 its presence upon Ribcs in the timber at Dry Creek, about 6^ miles 

 above Taylors Falls, a mile or more from the St. Croix River, and 

 approximately four miles from the above mentioned nursery designated 

 as Nursery A. Previous to this finding it had been discovered (June 

 4th) by the Nursery Inspection force in a row of large pines about 

 eighteen years old in a nursery forty miles or more south of the above 

 infested locality. (This nursery may be designated as "Nursery B.") 

 It was found on currants (uredospore stage) growing 75 feet from 

 these infected pine on June 20th. 



It is important to note at this point a fact which will be referred to 

 later that, as a result of a most careful investigation by the inspection 

 force upon pines in the earlv summer and later upon pines, currants and 

 gooseberries no evidence of this disease has been found in other 



