Chap. 42.] 
IKCTSIOKS MADE IN TREES. 
529 
Dog-star that irrigation is so particularly beneficial ; but even 
then it ought not to be in excess, as the roots are apt to become 
inebriated, and to receive injury therefrom. Care should be 
taken, too, to proportion it to the age of the tree, young trees 
being not so thirsty as older ones ; those too which require the 
most water, are the ones that have been the most used to it. 
On the other hand, plants which grow in a dry soil, require no 
more moisture than is absolutely necessary to their existence. 
CIIAP. 41. EEMABKABLB FACTS COKN-ECTED WITH lEEIGATION. 
In the Eabian district, which belongs to the territory of 
Sulmo^^ in Italy, where they are in the habit, also, of irrigating 
the fields, the natural harshness of the wines makes it neces- 
sary to water the vineyards ; it is a very singular thing, too, 
that the water there kills all the weeds, while at the same 
time it nourishes the corn, thus acting in place of the weeding- 
hook. In the same district, too, at the winter solstice, and 
more particularly when the snow is on the ground or frosts 
prevail, they irrigate the land, a process which they call 
warming " the soil. This peculiarity, however, exists in the 
water of one river^^ o^ily, the cold of which in summer is 
almost insupportable. 
CHAP. 42. (27.) INCISIOIS^S MADE IN TREES. 
The proper remedies for charcoal-blight and mildew^*' will 
be pointed out in the succeeding Book.*^ In the meantime, 
however, we may here observe that among the remedies may 
be placed that by scarification.^^ "When the bark becomes 
meagre and impoverished by disease, it is apt to shrink, and so 
compress the vital parts of the tree to an excessive degree : 
upon which, by means of a sharp pruning knife held with both 
hands, incisions are made perpendicularly down the tree, and 
a sort of looseness, as it were, imparted to the skin. It is a 
38 This was the native place of Ovid, who alludes to its cold streams, 
Tristia, B. iv. El. x. 11. 8, 4 :^ 
*' Sulmo mihi patria est, gelidis uberrimus undis, 
Millia qui no vies distat ab urbe decern.*' 
Irrigation of the vine is still practised in the east, in Italy, and in Spain ; 
but it does not tend to improve the quality of the wine. 
39 The Sagrus, now the Sangro. 
*o " Uredo rubigo " and " uredo caries." *i Co. 45 and 70, 
*2 Still practised upon the cherry-tree. 
VOL. III. M M 
