10 



tree, but its value for timber has been destroyed. Besides the insects 

 and fungi, diseases which may be characterized as physiological are 

 not uncommon. They may be due to an insufficient supply of light, 

 heat, water, or food. etc. Often insects and fungi act in conjunction 

 with other unfavorable agencies, and it then becomes a matter of con- 

 siderable difficulty to ascertain the true cause of the disease. The 

 present paper deals only with diseases due to fungi. 



The mycelia of fungi attack living trees as well as dead ones. When 

 on living trees they grow either in the living parts, the roots, leaves, 

 bark, or newer wood cells, or in the dead parts, the heartwood of the 

 roots, trunk, and branches. The character of the injury which the 

 myceliimi causes depends much upon its place of growth, whether on 

 the leaves or within the wood. Injury to the leaves may often be very 

 great, as is the case with fungi like the Erysipliec^, Uredinece. Kjcoos- 

 cece, and others. The injury caused by those which grow in the li^-ing 

 bark or cambium, like the species of Nectna. for instance, is very large. 

 A large class of fungi flotirishes within the heartwood of trees, 

 growing into it throtigh a branch or some wound, and in some cases 

 through the roots. The effect of their growth is to destroy the heart- 

 wood, filling it with holes or turning it to a brittle substance which has 

 none of the properties of ordinary wood. These changes weaken the 

 trunk, and at some period or other the tree is broken by the wind. 

 Tiose forms which enter through the roots may kill the latter first, and 

 tbus cause a tree to fall. The wood is then rapidly destroyed by a large 

 variety of fungi and insects. It is therefore to the interest of the for- 

 ester who grows trees for their wood to determine what fungi so 

 affect the trees as to render the wood unfit for lumbering purposes. 



In Europe, where forests have been grown for many years, the 

 importance of understanding the diseases of forest trees has long been 

 recognized, as is well shown by the works of Hartig. Tubeuf. Marshall 

 AVard. Frank. Xypels. and others. These show that it is possible to 

 prevent the growth of many of these fungi by destroying their fruiting 

 bodies, and. in general, by bringing about conditions unfavorable to 

 their growth and development. In order that this may be properly 

 and successfully done, it is first necessary to know what the destructive 

 fungi are and where and how they live. It was with this end in view 

 that the wi'iter spent several months during the year 189v» in the for- 

 ests of ]Maine. A preliminary survey was made of the forests of that 

 State, and the results are here presented in preliminary form. 



WHERE THE IXVESTIGATIOXS REPORTED WERE MADE. 



The region about Houlton in Aroostook County was first visited. 

 then the teri-itory north of ^loosehead Lake, and during September 

 the region about the Kangelev Lakes. A large part of the summer was 

 spent on the coast at Linekiu (near Boothbay Harbor, Maine), where 



