24 
ON BLIGHTS. 
There is another sort of blight that sometimes happens later in the 
spring, in April or May, which is often very destructive to orchards 
and plantations, which has hitherto baffled all attempts to prevent it—- 
this is called a fire blast, and in a few hours not only destroys the 
fruit and leaves, but very often part, and sometimes entire trees; this 
is supposed to be effected by volumes of transparent vapours which 
approach so near to a hemisphere in the upper or lower surface, as to 
concentrate the rays of the sun so as to scorch the plants or trees ; 
against this enemy there is no guard. 
Another sort of blight—But that blights are frequently no more 
than an inward weakness or distemper in trees, will evidently appear, 
if we consider how often it happens that trees against the same wall, 
and aspect, and enjoying the advantages of sun and air, with every other 
circumstance which might render them equally healthy, are very often 
observed to differ greatly in strength and vigour; indeed, we gene¬ 
rally find weak trees to be blighted, when vigorous ones in the same 
situation escape, which must be in a great measure ascribed to their 
unhealthy constitution. This weakness in trees, therefore, proceeds 
either from the want of sufficient supplies of nourishment to maintain 
them in perfect vigour, or from some ill qualities in the stock, or 
distemper of the buds or scions, which they had imbibed from the 
parent trees, or from mismanagement in pruning, &c., all which are 
productive of distempers in trees, and of which they are with difficulty 
cured. Now, if that be occasioned by weakness in the trees, we should 
endeavour to trace out the true cause; first, whether it has been occa¬ 
sioned by bad pruning, which is often the case; for, how frequently 
do we observe peach trees trained up to the full extent of their 
branches every year, so as to be carried to the top of the wall in a few 
years after planting; when, at the same time, the shoots for bearing 
have been so weak, as scarcely having strength to produce their flowers, 
this being the utmost of their vigour, the blossoms fall off, and many 
times the branches decay, either the greater part of their’* length, or 
quite down to the place from whence they were produced; whenever 
this happens to be the case it is ascribed to a blight. Others there are 
who suffer their trees to grow fast, as they are naturally disposed 
during the summer season, without stopping the shoots or disburden¬ 
ing the trees of luxuriant branches, by which means two, three, or four 
shoots will exhaust the greater part of the nourishment of the trees all 
the summer, which shoots at the winter pruning are entirely cut out, 
so that the strength of the trees is employed only in nourishing useless 
branches, and they are thereby rendered so weak as not to be able to 
