212 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



were establislieil in the New Ent^land States and New York. Elforts 

 wi'ro made to eradicate the spot infections in Wis onsin and Minne- 

 sota and to rid infected nurseries of the disease. At the same time, 

 extensive scoutinjj: was coiuhicted to detei'mine tlie e.xad conditions 

 in these States. This work was continued in 1918, but on account of 

 tlie w^ar and difliculties incident tiiereto it was reduced to a minimum. 

 Scoutin<r in 1S)U) showed that the disease was present in 9 counties 

 in \\'isconsin and 14 counties in jNIinnesota eitiier on pine or Ribes 

 or on both hosts. The attempt to exterminate the disease in these 

 States was immediately o^iven u[) and the Avork placed on a loral 

 contnd basis, as in the New En<^land States and Ncav York. With 

 the exception of one diseased planted pine in ^Slicliijran and one in- 

 fected patch of black currants in New Jerse3\ no si<2;n of the blister 

 rust was found in 1919 outside of the generally infected States of 

 New England, New York, Wisconsin, and Minnesota. 



COOPERATION IN lU.ISTER-RUST CONTROL. 



Formal or informal cooperation has been established with all 

 States except Florida, Alabama, JNIississippi, and Louisiana, where 

 there are no five-needled pine interests. In the New England States, 

 New York, Pennsylvania, Wisconsin, and Minnesota, control work is 

 placed on a dollar-for-dollar basis, Avhereby one dollar is spent from 

 Federal funds for each dollar spent by the State and cooperating 

 tow^ns, associations, and individuals. In all cases wild and cultivated 

 Ribes are eradicated in cooperation with and under the legal author- 

 ity of the States concerned, the Bureau of Plant Indu-try only assum- 

 ing responsibility for locating the disease and for securing the great- 

 est possible efficiency in the cooperative expenditures. Systematic 

 scouting for diseased pines and Ribes is being conducted outside the 

 region of general infection, wherever there is a possibilit}- that spot 

 infections of the blister rust may exist. If necessar}', the eradication 

 of these secondary infections is attempted by the removal of all pines 

 or Ribes. or both, under State authority. Nursery shipments of five- 

 needled pines or Ribes known to be or susj^ected of being infected 

 or which are shipped in violation of Federal quarantines are traced 

 and reported to the State authorities for action. Since the States 

 south of Pennsylvania and west to the Great Plains have been quite 

 thoroughly scouted in previous years, work has been reduced to the 

 minimum in these States, and special emphasis is being given to. 

 scouting in the Rocky IMountain and Pacific Coast States. 



RATE OF PINE INFECTION. 



The general distribution of the blister rust on Ribes over a number 

 of years is causing severe damage to white-pine trees in many locali- 

 ties. Infected pine areas varj'^ in size from a few pine trees Avithin 

 100 feet of a single infected currant or gooseberry bush to over 50 

 per cent of the pines within a radius of one-half mile from plantations 

 of diseased cultivated bushes. Strip surveys in the toAvn of Littleton, 

 N, H., show that 2G.4 per cent of the native pines on an area of 72 

 square miles are infected with blister rust. Wild gooseberry bushes 

 are responsible for this infection, the cultivated bushes being negli- 

 gible. The oldest pine infection found on this area occurred in 1906, 



