506 On the Protection of the Blossoms of Wall Trees. 



those by which the trees are thickly covered during the night, 

 and fully exposed during the day ; and if this kind of pro- 

 tection be given to Peach and Nectarine trees very early 

 in the spring, it not only preserves the blossoms, but it also 

 prevents the appearance of blistered leaves, which are gene- 

 rally abundant in cold and unfavourable seasons. This dis- 

 eased state of the leaf is often confounded with that which 

 is occasioned by the bite of the Aphis ; but it is in its origin 

 wholly different from that, and arises solely from the leaf 

 having, whilst very small and young, been injured by frost. 

 The trouble and expense of so frequently applying and 

 removing the covering of Wall trees, and the destruction of 

 their blossoms, which almost necessarily occurs, compel the 

 greater number of gardeners to apply only such kinds of 

 covering, as, when once applied, may remain unmoved, till 

 the danger from frost is nearly past. Amongst these, woollen 

 nets, or a patent imitation of netting, which may be obtained 

 at a much lower price, constitute the best material : but it is 

 expedient that the meshes should be sufficiently wide to per- 

 mit the ingress of bees ; for the pistils of the blossoms of 

 almost all Fruit trees are not in the best state to receive the 

 pollen, till the anthers of the same blossoms have become 

 expended, and the number of blossoms, which are rendered 

 productive of fruit by their own proper pollen, is not, I have 

 reason to believe, very great. The exclusion of honey- 

 gathering insects is consequently in most cases very injurious. 



The material which I employ, and which I proceed to re- 

 commend, is every where obtainable, and at an extremely 

 small expense. It consists of small branches, about two feet 

 in length, of the Birch tree, collected as soon as the leaves 



