I 10 



DISEASES OF TREES 



brown till October, and the formation of perithecia begins on 

 the three-year-old leaves in June of the following year, the spores 

 ripening in the succeeding March and April. The apothecia 

 appear as long, straight, lustrous-black ridges, for the most part 

 only on the two under sides of the leaf (Fig. 55). The spores 

 are about twice as long as those of H. nervisequium. It is 

 desirable that further investigation should be directed to this 

 and to the immediately preceding disease, because I have not 

 yet been able to clear up thoroughly many details in the develop- 

 ment of these parasites. Especially has no explanation so far 



FIG. 54. A spruce-branch, showing 

 brown leaves on the upper two-year- 

 old portion, and apothecia on the part 

 that is three years old. 



FIG. 55. Apothecia 

 on a spruce-leaf. 



been offered regarding the phenomenon of the leaves of the 

 youngest shoots of many spruces first becoming brown and 

 then dropping off in autumn, so that these shoots become 

 almost completely defoliated. Instead of long apothecia- 

 ridges developing on such leaves, small isolated apothecia- 

 tubercles similar to those of Hysterium Pinastri make their 

 appearance. 



HYSTERIUM PINASTRI* 



This is a species of fungus which is everywhere present in 

 pine woods, and has been identified by Goppert l as the cause of 



1 Goppert, Verhandl. d. schlesischen Forstvereins, 1852, p. 67. 

 * [Common in England. - ED.] 



