PROTECTION FROM FROST 



593 



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 pseudacacia) 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 pro- 

 tection of the inclosure. The fig, the walnut, the chestnut, seedling 

 almonds, and apricots are especially commended for such use. 



Growing Trees from Seed. 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 Trees. If one desires rapid growth of 

 shelter trees, they should be cultivated the first few years as thor- 

 oughly as an orchard. Much disappointment results from allowing 

 roadside trees to shift for themselves in a hard, dry soil. With such 

 treatment the root extension is naturally most rapid into cultivated 

 orchard ground, which is undesirable. Cultivate and enrich the 

 roadside, and the tree will grow chiefly on the waste land. At the 

 same time the roadside will be prevented from producing vast quan- 

 tities of weed seed, to be blown over the fence, and the place will 

 have a name for neatness, which is too rare even in California. 



PROTECTION FROM FROSTS 



Much attention has been given during recent years to the pro- 

 tection of citrus fruits as they approach maturity, and of deciduous 

 fruits as they are starting on their growth, from occasional 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 degrees if the ground surface is wet and the ex- 

 posure 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 orchard or vineyard with 

 a cloud of smoke. Both these protective measures fail when the 

 temperature falls a few degrees below 28 degrees or when such 

 freezing temperature is continued several hours. During the last 

 fifteen years, at Riverside, systematic invention and trial of frost 

 prevention has proceeded, and the satisfactory results of one device 

 is thus described by Mr. E. W. Holmes : 



