PKEFACE 



THIS book arose from an investigation which Sir William 

 Schlich asked me to make into the larch canker, a disease 

 on which many articles and papers have been published, 

 though no full and connected account of it has ever been 

 written in English. While studying the canker in the field, 

 I very frequently encountered certain other diseases on the 

 larch, especially the heart-rot and the honey fungus, and it 

 seemed better to include these in the scope of the investi- 

 gation. For the sake of completeness, all the known diseases 

 on the common larch have also been described, and it is 

 hoped that a book of more general usefulness has been 

 thereby produced. Certain fungi, such as Lophodermium 

 laricis and Botrytis cinerea, which have occasionally been 

 reported as parasitic on the larch, have been omitted, as no 

 reliable evidence of their causing disease has been forth- 

 coming. 



The arrangement of the diseases bears no relation to the 

 systematic position of the fungi. They are mostly given in 

 the order in which they were studied, which approximates 

 closely to the order of their importance. 



The work was made possible by a grant from the De- 

 velopment Commissioners, received through the Board of 

 Agriculture and Fisheries, and latterly through the Interim 

 Forest Authority. Especial acknowledgement is due to 

 these departments, particularly to the last named, which 

 has assisted me in a variety of ways. I also desire to thank 

 Sir William Schlich for constant help and encouragement, 

 and Messrs. A. W. Borthwick and Malcolm Wilson for 

 permission to reproduce Fig. 72 from the Transactions of 

 the Royal Scottish Arboricultural Society. 



OXFORD, August 1919. 



