100 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



from frosts is experienced. There are 

 many places in our mountains known as 

 thermal belts, which are said to be en- 

 tirely free from frost. Whether or not 

 this is claiming too much, it is certain 

 that distinct lines can often be seen sep- 

 arating bright, fresh verdure above and 

 blackened, frost-bitten foliage below. 

 Similar lines of demarcation can be seen 

 in spring between the early growth on 

 the hillsides and the dormant buds of the 

 valley below. In summer over the same 

 area can be seen a distinct cloud line 

 marking the height of the fog in the 

 valley below, while above it on the hill- 

 side will be cloudless air bathed in sun- 

 light. In the fall, when frosts have 

 claimed all the tender vegetation of the 

 valley, there will be seen longitudinal 

 bands skirting the hillsides, showing for 

 a month or six weeks all the freshness 

 of summer. Though the exact borders of 

 these thermal zones cannot be located 

 with precision, their general position is 

 fairly constant. Orchards planted on 

 thermal belts are remarkably regular in 

 fruit bearing. There are many orchards 

 in the mountains where old settlers claim 

 they have never seen a failure in a crop 

 from frost. The reason for these peculiar 

 phenomena is undoubtedly the draining 

 of cold air from the hillsides and its 

 stratification in the valleys below. There 

 are other circumstances connected with 

 thermal belts that have not yet been fully 

 worked out. However, there is at pres- 

 ent suflScient practical evidence of the 

 value of thermal belts in frost protection. 

 Fruit growers should not fail, where pos- 

 sible, to take advantage of them in or- 

 chard planting. 



W. N. HUTT, 



Raleigh. N. C. 



Rolling Land Xortli Slope 



The Dest site for an orchard is gently 

 rolling land with a north or northeast 

 slope. Always avoid flat land or valleys 

 for cold air, being heavier than warm 

 air, settles to the lower places and frost 

 is more likely to kill the blossoms in 

 such locations. If planted on the south 

 side of a hill the trees will be warmed 

 by the sun in spring, and. being pro- 

 tected from the cold north winds, will 



blossom early and may be killed by frosts. 

 On the north slope the cold winds will 

 keep them in a dormant condition longer 

 or until danger of frost is past. Much of 

 the land that is too hilly for profitable 

 production of other crops will produce 

 good crops of apples if given the proper 

 care and attention. 



H. C. Thompson, 

 Agiicultui-al College, Miss. 



.4jr Drainage and Frost 



In mountain regions, besides the 

 draining of water from higher to lower 

 levels, there is a similar drainage of air. 

 This latter might seem to be of trifling 

 importance in fruit growing, but it is in 

 fact one of the most important considera- 

 tions, for it tends greatly to avert frost. 

 Freezes and frosts are undoubtedly the 

 greatest hazard of the business of fruit 

 growing. No disease or depredator de- 

 stroys half so many hopes and dollars 

 for the fruit grower as a few hours of 

 frost. We are told that "the frost falleth 

 alike on the just and on the unjust," but 

 in seasons when the daily papers are her- 

 alding reports that an untimely frost has 

 taken the entire fruit crop of the state 

 some lucky fellow high up in his moun- 

 tain coves, with not too many good works 

 to his credit, has his entire crop saved as 

 if by miracle. Frosts appear to strike in 

 a very erratic manner; they are, however, 

 like other phenomena of nature, subject to 

 very definite laws. It is well known that 

 as air becomes heated it ascends, and as 

 it cools it becomes heavier and falls. On 

 sloping ground air as it cools passes 

 down from higher to lower levels. Other 

 things being equal, low lands are more 

 frosty than higher lands, because the 

 cold and frosty air drains from the higher 

 and settles into the lower levels. A corn 

 field in the fall gives one of the best il- 

 lustrations of the places most subject to 

 frost and those also which are exempt. 

 On the bottom lands the blades and stalks 

 will almost invariably show where frost 

 has bitten first. Up on the hillsides and 

 higher elevations the corn will often be 

 found growing fresh and green, while in 

 the bottoms below not a green stalk can 

 be seen. Where knolls occur in bottoms 



