LOPHODERMIUM. 



237 



suffered by it should, where other soil conditions permit, be 



planted with Weymouth pine {Pinus Strohus) and the Douglas 



fir (Pseudotsuga Douglcmi), which are, as yet, exempt from 



attacks of this parasite. Infection would seem to be brought 



about chiefly by westerly winds (in Germany), which carry 



diseased leaves or fungus-spores from infected 



places. Large areas run greater risks than 



small patches or young trees naturally sown 



out. Seed-beds of Scots fir should not be 



placed under the drip of older trees of the 



same kind, particularly if this fungus is 



known to exist there. Shelter- belts of other 



trees often afford much protection from this 



disease.^ 



Lophodermium macrosporum Hartig - 

 {Hgsterium). (U.S. America). Scab or rust 

 of the spruce. This disease exhibits itself 

 in various ways. Frequently the needles of the preceding 

 year turn brown in spring, and perithecia are produced in 



Fig. 121.— 1, Lophoder- 

 laiv.m luacrosporuni on 

 Spruce, (v. Tubeuf del.) 



2, Lo)>h(nlermium ahi- 

 ctis on Spruce. (After 

 Ro.strup.) 



Fio. 122.— Loiyhodenniv.m maa-osporum. Section tliruugh a mature dehiscing 

 apothecium. (After R. Hartig.) 



summer, reaching maturity on two-year-old needles. Again, the 

 needles of the two-year-old shoots become brown in autumn, 

 and perithecia appear on them in the following summer, 



■ Preventive measures are discussed in greater detail in Prof. Somerville's 

 translation of Hartig's Diseases of Trees, p. 115. 

 -R. Hartif', Wichdqe Krankheilen d. Wahlhaume, 1874. 



