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mystery disease of eastern white pine 



By MALCOLM A. McKENZIE, Director of Shcde Tree Loboratories 



NEEDLE BLIGHT, a disease re- 

 sponsible for the reddening of 

 new needles of white pine trees, is 

 still a puzzle to medical men of the 

 forest. Known since 1900, the dis- 

 ease has killed relatively feAv white 

 pines. Although present almost every 

 year to a limited extent, it appears 

 suddenly, as during the past summer, 

 to cause great alarm among tree men. 



Countless Causes Cited 



Needle blight has been attributed 

 to a variety of physiological condi- 

 tions: too wet, too dry, too hot, too 

 cold. In 1954, it was first noticed 

 during a short period of hot dry 

 weather after a record-breaking wet 

 spring that had favored lush foliage 

 development. 



The disease is quite distinct from 

 the white pine blister rust, the 

 familiar rust fungus disease. In fact. 



no fungus or insect has been found 

 consistently on affected trees. 



Appropriately Named 



From its appearance, the disease 

 is appropriately called needle blight, 

 but the primary cause of the injury 

 is more likely associated with a 

 damaged or inadequate root system 

 and with the surrounding area. 



In acute cases, the needles may be 

 of normal size; in chronic cases, 

 shorter. 



Individual Trees Involved 



The disease is not dramatic in its 

 attack, for it does not sweep through 

 a stand leaving its devastating mark 

 but singles out one tree as its victim 

 and goes on to a second in another 

 group. 



Any conditions that damage or re- 

 tard rootlets might explain the fact 



Reddish-brown needles (white in photo) 

 on affected tree in foreground contrast 

 sharply with the normal dark-green pine 

 (black in photo). The brown or straw 

 color of older needles is sometimes con- 

 fused with needle blight. Evergreens 

 near the coast may be damaged by salt 

 spray carried by high winds. This dam- 

 age resembles needle blight somewhat. 

 The conspicuous difference is the con- 

 sistent damage to all trees directly ex- 

 posed }o the spray. 



Pholo by Robert L. Coffin, 



