12 WOKK ().\ TIIK W IllTK I'lXl-: lU.lSTKK KfST IN M I X X KSOTA 



nurseries, and al! ])riniary infestations so far discovered occur witliin 

 two miles of our eastern boundar\. This is important in considerinji: 

 the possiljle source of Minnesota's infestation. Up to date this disease 

 has not Ijeen (Hscovered in this state west of the Mississippi River, 

 except on a few pines shipped from Xursery A and destroyed before 

 blisters appeared 



On September 23th, l')16. Mr. Coe, a field worker in connection 

 with this disease, employed l)y the State Entomologist, and Mr. Salmon, 

 working for the V. S. IJureau of I'lant Industry, found in the course 

 of a blister rust surve\- of the St. Croix reigon between Stillwater and 

 Taylors b'alls. a fourth "center" of infestation upon wild currants and 

 gooseberries, close to the St. Croix at a point known as Pine Hollow^ 

 Creek, three miles below Osceola on the ^Minnesota side. This discov- 

 ery was made so late in the season that lea\es were already falling and 

 any attempt towards eradication would have been futile. Many of the 

 pines at this ]:oint are undoubtedlv now infested. This infestation 

 appears most serious. It was first reported as covering an area of about 

 thirt\-five acres, but was later roughly estimated as covering fifty acres. 

 Both here and at Dry Creek the deciduous growth is mingled with pines 

 of various sizes. The latter place has a magnificent stand of large 

 white pines, representing many thousand feet. In both localities pines, 

 currants and gooseberries occur abundantly in ravines of varying width 

 and length, and in these localities the disease was found most abun- 

 dant. There appears to be a definite relationship between this abundance 

 and the drawing of the wind up these miniature canyons. It is (|uite 

 possible and even i)robal)le that further survey along the St. Croix will 

 d.isclose the presence of the rust in other localities in that \icinit\-. 



POSSIBLE SOURCES OF MINNESOTA'S INFESTATION. 



While it is not possible at this date to state definitely the actual 

 source or sources from which Minnesota obtained this disease, bevond. 

 of course, the one introduction of diseased trees 1)\- Xurserv A in the 

 spring of V>\5, certain facts point most strongly to the probability of 

 its coming from Wisconsin. We know that disea.sed trees were brought 

 to St. Croix Falls in 1908 or 1909. or in both years. It was a portion 

 of these trees planted at Lake Waui)agasset. Polk County. Wisconsin, 

 which first called our attention to the ])resence of the rust so near our 

 eastern border, and which this }ear (and pre\-iousl\ ; ) infested a large 

 area in the neighborhood of the above mentioned lake near the St. 

 Croix. 



