156 OUR FORESTS AND WOODLANDS 
is obtained about the age of seventy or eighty 
years. On the most favourable classes of soil 
it will often pay well only to fell it at eighty or 
a hundred years, but in less favourable situations 
it may have to be harvested at about sixty years 
of age to escape the danger of becoming black 
in the heart and unsound in consequence of a 
fungous disease caused by Necétria ditissima. Par- 
ticularly common in soils of a very limy nature 
this disease soon works its way up from the butt 
into the top of the bole and the main branches, 
and renders the tree unfit for timber. Where 
prevalent the disease often attacks the ash while 
still in the earlier stages of growth, and pro- 
mising young plantations are sometimes very 
speedily and completely ruined from this cause. 
Seedlings also suffer, on soils unsuited for ash, 
from another fungous disease due to Phytophthora 
omnivora, which also often attacks beech seedlings 
at the time of their germination. 
Wherever seed-bearers are in the immediate 
neighbourhood, ash comes up freely on most 
kinds of soil. ‘Ash cometh up everie where 
of it selfe, and with everie kind of wood,’ Holin- 
shed truly remarks. In some of the beechwoods 
