THE NOVAR SYSTEM OF COMBATING LARCH DISEASE. 41 
but instances of such virulence are, on the whole, of rare occurrence. The 
trees that are retained are the picked stems of the three to four thousand 
originally occupying the ground ”—z.e., 34 by 34 feet=3556 per acre—‘‘ and 
measure up to 51 feet in height and 4 to 8 inches in diameter at breast-height. 
Stems that are sound, or fairly sound, at this age are not likely to suffer much 
from disease in later life.” 
This does not expressly state, in so many words, that of about 
3500 larch originally planted at least 3000 to 3200 are 
cankered stems ; but this is apparently distinctly implied, be- 
cause the soil-quality being evidently the same (as is shown by 
the planting of about 3500 per acre in each plantation), Mr Munro 
Ferguson would probably prefer in all cases to have a crop of 
500 sound, non-cankered poles, if he could grow them, rather 
than one of 300 poles only. And this means that from over 85 
to nearly go per cent. of the larch planted become attacked with 
the disease to such an extent as to show cankerous wounds, 
from each of which the fungus-fruits formed tend to perpetuate 
the disease, and to increase its prevalence by emitting countless 
myriads of spores ready to germinate under favourable circum- 
stances—one of the most favourable of these latter being, in our 
damp climate, the formation of pure larch woods. 
And while it is true that stems which are clean and sound 
in the bole at 16 or 20 years of age are not likely to show 
canker-wounds later on in the lower part of the stem, it does 
not at all follow that they will not suffer from canker in the 
crown, as has been found from experience to have been the 
case during the last twenty-five years in Ireland, before which 
time the larch disease was almost or quite unknown, but where 
it has now become as prevalent and as destructive as in any 
part of Britain. 
Hence even the soundest 300 to 500 stems of such pure 
larch plantations are exceedingly likely to become cankered 
in the crown subsequently, and in due time to become also 
the further means of propagating and disseminating the disease- 
producing spores. 
Would it not perhaps be a better plan to try and combat the 
larch disease by planting, as the bulk of the crop, the shade- 
enduring conifers named as suitable for underplanting, and at 
the same time interplanting them with stout healthy larch, either 
set singly or in small groups, to the number of about 430 to 
650 per acre, ze, from 8 to ro feet apart? This would give 
