REPORT OF THE SOCIETY 39 



receive regularly from all parts of our forest area reliable reports upon all 

 important insect injuries. With this system in operation it will be possible 

 to discover insect outbreaks in their initial stages, to make an expert examin- 

 ation and to put in effect whatever direct control measures may at that time 

 have been devised. 



The perfection of this intelligence system will prove without question a 

 most effective aid in avoiding and controlling serious forest insect injuries. 



CHEMICAL WOOD PULP IS ATTACKED BY MOLDS 



By R. J. Blair, Pathologist, Forest Products Laboratories of Canada 



Wood pulp manufacture falls into two main divisions known as the 

 mechanical and chemical processes. Mechanical pulp often spoken of as 

 groundwood is made in a machine where sticks of wood are held against a 

 revolving grindstone. For chemical pulp the wood is first cut into chips 

 which are cooked in large digestors at high temperatures under pressure. 

 For cooking the chips the digester is filled with a chemical solution which 

 dissolves the hgnin from the wood leaving the fibre behind in a more or less 

 impure form of cellulose. According to the chemical used for the cooking 

 liquor, three different kinds of pulp are made known as sulphite, sulphate 

 and soda. Each of these kinds of pulp may be subsequenth' bleached. 



An idea of the importance of the industry to Canada may be obtained 

 from the following figures. In 1920, 2,777,422 cords of pulpwood were manu- 

 factured into pulp by the various processes. The wood used and pulp produced 

 are as follows: 



Kind of Pulp Cords of Wood Tons of Pulp 



Groundwood 1,080,618 1,090.114 



Sulphite 1.354,023 675,733 



Sulphate 330,907 188.487 



Soda 11,874 5,768 



Part cf this output is made into paper immediately but a considerable 

 portion is either exported or stored in Canada before it can be used up. For 

 various reasons several months often elapse from the time the pulp is manufac- 

 tured until it is made into paper and it is during this interval that losses due 

 to molding occur. 



Work upon the molds affecting groundwood pulp has been carried on by 

 the Bureau of Plant Industry of the United States Department of Agriculture, 



