OP FRUIT TREES. 83 



various kinds ; and Mr. Knight has remarked, that 

 they also fail frequently from want of impregnation 

 when the weather is unusually hot and dry, or when 

 cold winds prevail, as he often observed the farina 

 to wither and die on the anthers in such seasons. 



Spring frosts are an enemy, against which per- 

 haps it is most difficult to guard orchard trees. " Dry 

 frosts," says Marshall, " are observed to have no 

 other effects than keeping the blossoms back ; con- 

 sequently, are frequently serviceable to fruit trees. 

 But wet frosts, namely, frosts after a rain, or a fog- 

 gy air, and before the trees have had time to dry, 

 are very injurious even to the buds. An instance 

 is mentioned, in which a flying hazy shower in the 

 evening was succeeded by a smart frost ; that side 

 of the trees, against which the haze drove, was en- 

 tirely cut off, while the opposite side, which had 

 escaped the moisture, likewise escaped the effect of 

 the frost. Much, however, may depend on the 

 strength of the blossoms. When the buds form, 

 and the blossoms break forth with unusual vigour, 

 they are enabled by their own strength to set com- 

 mon enemies at defiance. But, on the contrary, 

 when the blossoms sicken in the bud, and those 

 which open are weak and languid, scarcely an ap- 

 ple will be produced. The assistance, therefore, 

 required from art, in this case, is by keeping the 

 trees in a healthy, vigorous state, to enable them to 

 throw out a strength of bud and blossom; and by 

 keeping them thin of wood, to give them an oppor- 

 tunity of drying quickly before the frost sets in." 

 Apple blossoms are, in some seasons, injured by the 

 devastations of an uncommon number of insects pro- 

 duced from a species of black flies, which deposit 

 their eggs in the bud at its first opening, and which, 

 by feeding on the heart of the bud, soon occasion it 

 to contract and drop. To remedy this fatal effect, 

 we are advised to collect heaps of long dung, wet 

 straw, weeds, &c., to dispose them in different parts 



