BOOK X\'II. xL. 24C)-.\Lii. 251 



XL. Irrigation is good for trees in the heat of imgatwn 0/ 

 snmmer but bad for them in winter ; in the autumn "'^"* 

 its effect varies and depends on the nature of the 

 soil, inasmuch as in the Spanish provinces the vin- 

 tager picks the grapcs when the ground is imder 

 water, whereas in thc greater part of the world it 

 pays to drain off the rain water even in autumn. 

 Irriffation is most beneficial about tlie risinjj of the 

 Dogstar, and even then not too much of it, because 

 it hurts the roots when they are soaked to the 

 point of intoxication. The age of the tree also 

 controls the due amount ; young sapHngs are not 

 so thirsty. But those that require most watering 

 are those that have been used to it, whereas those 

 which have sprung up in dry places only need a 

 bare minimimi of moistiu"e. 



XLI. The harsher vines need to be watered, at all 

 events in the Fabii district of the territory of Sulmo 

 in Italy, where they irrigate even the plough-land; 

 and it is a remarkable fact that in that partof the coun- 

 try water kills herbaceous plants but nourishes corn, 

 and irrigation takes the place of a hoe for weeding. 

 In the same district they irrigate the land round the 

 vines at midwinter to prevent their suffering from 

 cold, the more so if snow is hing or there is a frost ; 

 this process is there called ' warming ' the vines, 

 owing to the remarkable influence of the sun on the 

 river," which in sumrner is ahiiost unbearably cold. 



XLII. We sliall point out the remedies for fflowini;- xviir. 

 coal-bhght and mildew in the next Book. In the ' 

 meantime the Ust of remedies includes a sort of Scarificaiim 

 scarification. The bark when rendcred meagre by ""meUtsjor 

 disease shrinks up and exerts an undue amount of ""««• 

 compression on the vital parts of the tree ; for this 



