468 PROTECTION AGAINST FUNGI. 



due to the fungus requiring from six months to three years to 

 develop its sporocarps. At first, the needles are more resis- 

 tant, but when the tree becomes weakened, they are more 

 easily killed. 



In the case of needle*cast a more virulent form of the 

 disease occurs, and the needles turn red in August, then 

 brown, and fall before the winter. 



The spores of all species of Lophodermium gain admission 

 through the stomata, and the wetter the weather, the sooner 

 the spores ripen. 



b. Subjects of Attack, and Distribution. 



The disease affects chiefly pure crops of 15 to 30 years old 

 spruce, especially in the lower part of their crowns, but is 

 unimportant except when needle-cast takes place. Dense 

 crops are most affected ; mixtures of spruce with other species 

 suffer less. The mineral nature of the soil and the altitude 

 appear to have no influence, but in Saxony, the disease is 

 worst on fertile, moist soil and on S. and W. aspects, where 

 the spores ripen, at the time of the prevailing winds. When 

 badly attacked, the trees die, in the third year of an attack. 



c. Protective Measures. 



i. Avoid pure crops of spruce, wherever the disease is 

 common. 



ii. Cut out and burn affected subjects. 



iii. Eemove the soil-covering of dead needles near affected 

 trees, and do not use this litter in spruce woods. 



21. Lophodermium nemsequium, D. C. 



This is a very similar fungus to that described above, and 

 affects the previous year's and older needles of silver-fir, 

 turning them brown and eventually causing them to fall from 

 May to July. Numerous dark brown pustules may be noticed 

 on the upper surface of infected needles, and long dark-brown 

 sporocarps eventually break out in the mid-rib of their lower 

 surface. The spores are only half the size of those of No. 20. 



They ripen in April of the succeeding year, on the needles 



