130 PLANT DISEASES 



SPRUCE NECTRIA 



(Nectria cucurbitula, Fries.) 



Hartig has furnished us with an elaborate account of 

 this wound-parasite, of which the following is an abstract. 



The spruce is most frequently attacked, rarely the silver 

 fir or Scots pine. Entrance to the tissue of the tree is 

 often through wounds made by the larva of the moth 

 called Grapholithj, pactolina^ also through bruises caused 

 by hail, or cracked branches. 



The cortex is the portion most directly affected by the 

 fungus, although when this is killed, and especially when 

 it happens near the top of the tree, the wood also dries 

 up, and the top of the tree becomes yellow, withers, 

 and dies. 



The mycelium is most luxuriant in the sieve-tubes of 

 the soft-bast, and grows most vigorously when the growth 

 of the tree is at a standstill. If the dead bark is almost 

 constantly damp, numerous whitish stromata burst through 

 to the surface ; these first bear conidia, followed at a later 

 period by crowded red perithecia containing spores formed 

 in asci. 



PREVENTIVE MEANS. It is considered advisable to 

 cut off and burn the tops of dead trees to prevent the 

 spread of the disease. 



Hartig, Unters. aus dem forstbot. Inst. zu Munchen^ 

 vol. i. p. 88, i pi. 



Hartig and Somerville, Diseases of Trees, p. 89, figs. 



