Protection from Frost Injury. 407 
walnut makes a very satisfactory growth both in the interior and 
upon the coast, and is largely used for roadside planting. The 
California broad-leaved maple (Acer macrophylla) is very beau- 
tiful, rapid in growth, and dense in foliage, and the same is true 
of the box elder (Acer negrundv), but probably both trees are 
especially suited to the coast regions. Of the poplars, the 
Carolina (Populus monilifera) is best, because of its breadth, 
density of foliage, and comparative freedom from suckering. 
The locust (Robinia pseudacia) is used to some extent, but its 
suckering is very objectionable. 
Quite a number of the larger-growing deciduous fruit trees 
are used to some extent along the exterior lines of orchards for 
the protection of the inclosure. The fig, the walnut, the chest- 
nut, seedling almonds, and apricots are especially commenced 
for such use. 
Growing Trecs from Secd—Much that has been said in 
Chapter VIII will be suggestive to one who desires to grow his 
own shelter trees from seed. Trees from small seeds are best 
grown in boxes, and in many cases, as with eucalyptus and 
cypress especially, do best when put in permanent place when 
quite small. Whether put at once in permanent place, or in 
nursery, the land should be deeply worked and the young plant 
well planted and cared for. 
Cultivation of Shelter Trecs.—Ii one desires rapid growth 
of shelter trees, they should be cultivated the first few years as 
thoroughly as an orchard. Much disappointment results from 
allowing roadside trees to shift tor themselves in a hard, dry 
soil. With’ such treatment the root extension is naturally most 
tapid into the cultivated orchard ground, which is undesirable. 
Cultivate and enrich the roadside, and the tree will grow chiefiy 
on the waste land. At the same time the roadside will be pre- 
vented from producing vast quantities of weed seed, to be blown 
over the fence, and the place will have a name tor neatness, 
which is too rare even in California. 
PROTECTION FROM FROSTS. 
Much attention has been given during recent years to the 
protection of citrus fruits as they approach maturity, and of de- 
ciduous fruits as they are starting on their growth, from occa- 
sional fall of the mercury a few degrees below the freezing point. 
It has been shown by ample experience that fruits may escape 
injury by a temperature of 28° if the ground surface is wet and 
the exposure be but of short duration. Fruit has, therefore, 
been saved by irrigation, while that over dry ground has been 
nipped by the same temperature. About the same result has 
been secured by checking radiation of heat by covering the or- 
chard or vineyard with a cloud of smoke. Both these pro- 
