18 BULLETIN 247,, U. S. DEPARTMENT OF AGRICULTURE. 



cinium are commonly parasitized. This subject is now being in- 

 vestigated by the writers. 



The recommendations here given are based on observations made 

 in forests by the senior writer and not on actual experiments. An 

 attempt to control this disease as recommended here has been 

 planned and will probably be carried out in 1915. Until it is certain 

 that the neighborhood of a nursery is free from this fungus, ship- 

 ment of stock to uninfected forests should be avoided. 



The spraying of pines with Bordeaux mixture or other fungicides 

 for the prevention of infection by Cronartium pyriforme can not be 

 recommended until it is known that this method is effectual in con- 

 trolling the disease. 



The spraying of Comandra plants with a poisonous substance to 

 kill the foliage and tender shoots at the time they might be infected 

 from the aecial form of the fungus on pines should prevent the imme- 

 diate spread of the disease to the pines in adjacent nurseries. This 

 spraying should be done as soon as the leaves of the Comandra plants 

 are fully developed and before the plants bloom. This would prob- 

 ably be from the latter part of May to the middle of July, depending 

 on the altitude and the latitude of the locality. Should the Coman- 

 dra plants send forth new growth later in the season it might be 

 necessary to spray a second time. Spraying should be repeated each 

 year as long as any Comandra plants remain alive. Where young 

 pines are present, this method could not be used without killing them, 

 and the uprooting of the Comandra plants is recommended for such 

 areas. 



Mr. H. R. Cox, Agriculturist of the Office of Farm Management, 

 Bureau of Plant Industry, has prepared a circular letter giving direc- 

 tions for the use of plant poisons in killing vegetation. This circular 

 follows, more complete directions being obtainable from the office 

 mentioned upon request: 



For several years this office has been making tests of various chemical plant poisons 

 for killing all vegetation in such situations as driveways, pathways, tennis courts, 

 railroad rights of way, and similar places. It appears that of the substances there are 

 three that are better than any of the rest, namely, arsenite of soda, common salt, and 

 some form of petroleum. The best one of these for each case will depend upon condi- 

 tions. It seems to be more economical usually to make a number of comparatively 

 light applications for the purpose primarily of killing the foliage rather than one heavy 

 one to affect the roots as well as the tops. 



In the case of most kinds of vegetation excepting the grasses, and especially for 

 vegetation of a broad-leafed character, arsenite of soda is highly effective. The com- 

 mercial grade may be obtained at about 25 cents per pound from some of the wholesale 

 chemists. If large areas are to be treated, it can be made at home more cheaply by 

 boiling 1 pound of white arsenic and 2 pounds of sal soda in a gallon of water until 

 a stock solution is formed. From 10 to 20 pounds of the commercial arsenite of 

 soda or from 7 to 14 pounds of the white arsenic in the home-mixed formula, either one 

 diluted to make from 50 to 100 gallons of solution, is sufficient to kill most of the foliage 

 on 1 acre. 



