Montgomery County sentinel. [volume] (Rockville, Md.) 1855-1974, 1915-06-04
Blight OF Apple And Pear.

Blight is now prevalent on apple and
pear trees in nearly all parts Of Maryland.
On some apple trees practically all the
fruit has been destroyed. The loss in
many orchards in the State is very serious.
This disease has been present to some
extent ever since fruit was first grown in
this country. but some years becomes worse
than usual. 1t is also found on wild haw-
thorn, crab-apple. service berry, and on
many similar cultivated shrubs, 1t is very
injurious to ounces.
The blight first appears in the blossoms.
where the bacteria which cause it are car
ried by bees. or sometimes other insects
The germs multiply in the nectar of the
flowers, and from single such flower, bees
may infect the whole orchard.
This disease spreads downward from
the flowers between the wood and bark.
killing two to ten inches of the twig day,
but later it progresses more slowly, and in
apples usually dies out on the young twigs |;
but sometimes. and usually in pear. it keeps
extending. killing large branches. or the
whole tree. or forming cankers in the bark
in which the bacteria begin to multiply in
the exuding sap around the cankers. or
sometimes in late infected twigs. This is
the source of infection in the spring.
The blight often goes through short
spurs, or sprouts, or wounds of any kind,
into the body of the tree. even near or
below the ground. Many trees or large
branches are girdled and die in this way
every year.
The most effective treatment consists in
cutting out the diseased parts. In young
orchards and in nurseries where there is
naturally but little blight, and in old orchards
in seasons when blight is not serious, by
cutting out every blighted twie and canker
as soon as possible. giving special atten-
ton to the body and base of the tree. a
bad outbreak may be prevented in follow
ing years. 1t is also necessary to destroy
all blight in the neiehborhOod on wild or
cultivated trees as the bees may carry it
long distances. Bees are, however, neces-
sary to pollenate the flowers.
When old trees are badly infected, win
ter is the best time to cut out the blight.
The cuts on large branches or in the trunk
should be brushed with disinfectant and
when dry protected by painting with white
lead in linseed oil. In cutting blight in the
growing season. it is important to wipe the
pruning instrument after each cut on a
cloth or sponge wet with either carbOlic
acid. concentrated lime suffer, S per cent
formalin, or other disinfectant to prevent
re-infectiOn of the next cut. Cut twigs sew
eral inches below where the blight shows,
as in the spring the germs extend much
farther in than they show on the outside.
Keep water sprouts and all spurs off the
trunk and main limbs of pear and suscep-
tible apple varieties so that one useless
bliehted spur or sprOut may not girdle and
destroy whole branch Of the tree.
Some varieties, such as Yellow Trans
parent. Wealthy. York Imperial and Fall
Pippin apple and Bartlett pear are very
susceptible. others like Keiffer and Winesap
are less injured.
1t will be seen from the above that
little can be done now in badly affected
orchards to prevent further injury this
season. but the community should organize
to prevent the spread Of this serious dis
ease another year.
J.B. S. NORTON.
State PathOlogist