20 
THE CULTIVATOR 
HORTVCULTUBAL BEPAKfMEIT. 
CONDUCTED BY 
The Fear Blight. 
The past season has been unusually destructive to 
the pear tree. In some gardens, scarcely a tree has 
wholly escaped; and in many instances entire trees 
have been destroyed. The frequency and extent of 
this disaster is likely to prove a serious drawback on 
the general cultivation of this delicious fruit, which 
otherwise would rank, perhaps, second to none in im¬ 
portance. 
Doubts of the correctness of received theories of the 
blight, seem to be rather increased than diminished with 
this increased prevalence. Every additional fact must 
bo of importance, as every new aspect of the disease, 
whether for or against established theories, will enable 
us the better to look for a remedy. 
The Blight in the pear, is another name for death. 
When a branch suddenly dies, from whatever cause, 
its leaves turn black. If the limb be girdled, or lopped 
by breaking, or destroyed by insects, or poisoned by 
disease, the same external appearance is presented. 
But the infusion of poison may blacken the leaves more 
suddenly than mere mechanical causes. 
Two theories, it is well known, have been extensive¬ 
ly adopted, viz : those of the insect-blight, and the 
frost-blight. 
1. The first, which has been known for many years, 
and more especially adopted in New England, ascribes 
the mischief to an insect which, though very minute, 
or scarcely the tenth of an inch long, girdles a consid¬ 
erable portion of the interior of the branch, and thus 
cutting off, in part, the supply of the sap, when most 
wanted at a rapidly growing season, produces local 
death. Actual observation has proved that this insect 
is, in some cases, a cause of death in the branches of the 
pear. It must be so, however, to a very limited extent, 
as no traces of its work are seen by the closest micro¬ 
scopical examinations of affected branches, in most 
parts of the country. It also usually happens that a 
very large part, or nearly all of a branch, must be cut 
dcross to produce death, as any one may prove by the 
Use of a knife; hence it may be reasonably doubted if 
so minute an insect could always operate to a sufficient 
extent to produce the disaster, unless it infuses poison, 
of which there appears to be no evidence of a positive 
character. 
2. The most usual form of the disease is what has 
been of late years known under the name of frost- 
blight, or frozen-sap blight. This has been accounted 
for on the supposition that the severe frost of late 
autumn or winter, so affects the sap of unmatured 
branches as to destroy its healthy character, or to in¬ 
duce a change similar to that of fermentation, and thus 
to poison, instead of nourishing, the growing branches. 
This is supported by the following facts :—• 
1. Blight most usually attacks trees of late-growing 
or unmatured wood, or of such varieties as are not of 
compact growth. Hence trees on very rich or moist 
soils, which continue to grow luxuriantly till cold 
weather approaches; or such as have been checked at 
mid-summer, or pruned late, so as to produce a late 
second growth; or such as are remarkable for porous 
or spongy wood; are eminently liable to its attacks. 
The Madeleine and Bartlett have unusually spongy 
branches, and have long been known as extensive suf¬ 
ferers; while on the other hand, the Seckel and Sum¬ 
mer Bonchrietien, (though the latter is a rapid grower, 
it is of very close, compact growth,) have rarely been 
known to be attacked. Whether the frost operates on 
OHM J. THOMAS* 
the sap only, or on the unripened wood, or on both, m 
not a matter of so much consequence as the fact, ex¬ 
tensively proved, that good healthy trees, on a dry soil,, 
of moderate fertility, well cultivated, so as to produe©- 
a fair growth early enough to ripen thoroughly, am 
generally much safer from blight, than those under the 
unfavorable circumstances just mentioned. 
2. Blight has usually been found to prevail most ex¬ 
tensively after severe winters, preceded by warm, 
moist autumns; and has also in some cases been noticed 
to be very general within a few days after very sever© 
night frosts at the commencement of summer, when 
the new, tender and succulent shoots are easily affect¬ 
ed. The latter result was particularly noticed in 2844. 
It has also been since observed to follow immediately 
severe frosts at the same season of the year, which, 
were not noticed by any but early risers; and in on© 
ease, a frost was accidentally noticed near midnight, 
but was dissipated before morning by a warmer wind. 
Several cases of blight were soon after observed. This- 
last form of blight, which perhaps is direct and imme¬ 
diate death from the freezing of the young shoots, must 
be somewhat different from the true frozen-sap blight,, 
which often is not conspicuously manifested till several 
months after the first injury. It may often happen, 
however, that the diseased and fermented sap, from a 
frost-killed and succulent shoot, may run down th© 
larger branches, and rapidly spread the evil of its 
poisonous influence. Asa consequence, though nume¬ 
rous cases may suddenly follow the frost, the disease 
may prevail more or less from the same cause, for se¬ 
veral weeks afterwards. This result has been observed 
in two very distinct instances within a few years. 
There appear to be some cases of death in th© 
branches of the pear not satisfactorily accounted for 
by the above theories. P. Barry, in the Gen. Farmer , 
states that on his own grounds the blight has been un¬ 
commonly destructive the past season, attacking many 
healthy trees on hard dry land, with well ripened wood, 
including the Seckel, which has been thought by many 
to be proof against the disease. It is true, the land 
where they stood had been highly enriched by manure* 
but this did not cause a late unripened growth the pre, 
vious autumn. But the following fact is worthy of 
notiee: u In close proximity to these trees, stood thou¬ 
sands of young nursery trees, not one of which was 
affected.” Why should large trees, which ripen their 
wood so much better than young and rapidly growing 
ones, be alone affected ? The only tree on the grounds 
of the writer, at all injured the present year, was on© 
of rather slow growth, standing on drier, and firmer 
soil than most of the rest, which escaped. Not th© 
slightest mark of an insect could be discovered. 
In connexion with this subject, it may be stated that 
apple trees, as well as quince and hickory, have been 
extensively affected. But with the apple, the disease 
does not appear to extend down the branches as with 
the pear, but to be confined to their extremities. W© 
cannot discover, after much observation, that one sort 
of apple tree is more affected than another, although 
mostly confined to old trees; nor that warm frosty val¬ 
leys, where vegetation is most rapid, and cold most 
severe, on clear nights, favor the disease more than 
other localities. 
During the present year, the greatest number of 
cases were noticed to have occurred after a number of 
days of very hot, dry weather, towards the latter part 
of summer, when the trees had passed the season of 
