1910.] PUBLIC DOCUMENT — No. 31. 67 



perfectly healthy whose branches interlaced with those of 

 blighted trees. 



The number of pine trees affected with the so-called blight 

 or sun scorch in Massachusetts is probably less than 1 per cent., 

 and the number which have died is so insignificant that it is 

 hardly worthy of mention. ]\Iost of the affected trees have 

 periods of burning and periods of recovery. When new leaves 

 form, the old, blighted leaves drop off ; consequently, when a new 

 crop of foliage appears the tree no longer shows the effects of 

 blight. Trees which have blighted once have almost invariably 

 been affected again ; in other words, blighting has been confined 

 each year to certain trees. 



During the past five or six years the writer and his assistants 

 have examined a great many hundreds of pine roots from differ- 

 ent parts of the State, and have made many observations and 

 notes on the affected trees. Sun scorch of the pine has been 

 found to be associated with a very dry condition of the soil, aided 

 by severe winds. The side of the tree corresponding with the 

 direction of these winds is most severely affected, and many 

 instances may be found to prove this assertion. Moreover, that 

 part of a forest which is exposed to severe winds has shown 

 the greatest amount of blight. There has been more blight of 

 trees on the margins of forests than in the interior, and trees 

 growing in the open under exceptional conditions seldom if ever 

 blight. Small pines growing in the shade of older trees in the 

 forest have proved to be more or less susceptible, but they have 

 not been affected to such an extent by burning as by winter- 

 killing of the roots. Pines growing under such conditions are 

 not able to attain their best development in any season, and are 

 more likely to die from any cause that would tend to weaken 

 them than those growing in the open. 



Por the past five or six years the white pine has been looking 

 badly. It has been unusually susceptible to attacks of insects 

 of one kind or another, the pine borer killing the leaders in 

 many cases, and a black, scurfy-like growth on the foliage, 

 known as Scorias, has been more common than usual. ]\Iany 

 trees which have shown no inclination to burn possess a poor 

 root system which causes a yellow and sickly appearance of the 



