July, 1917 
WISCONSIN HORTICULTURE 
185 
also be caused by anything which 
interferes with the nourishment 
of the tree as lack of food or by 
black rot canker, scab, or winter 
injury. 
HOW TO CONTROL FIRE BLIGHT 
Fire blight is one of the most 
difficult orchard diseases to con- 
trol. The pruning knife, proper- 
ly used, is the only direct weapon 
against it. Blight cannot be con- 
trolled by spraying or protective 
washes. But these help to keep 
Blighted Blossoms 
in check insects which carry the 
( blight. Sprays, therefore, may be 
| indirectly helpful in fighting the 
I disease. 
■the TEN COMMANDMENTS OF FIRE 
BLIGHT CONTROL 
1. Cut out thoroughly all hold- 
over cankers. This should be 
done in the dormant period and is 
I more easily done by removing the 
blighted branches well below the 
points where the last signs of the 
j disease occur. If the branch is 
large and forms a part of the 
[ frame work of the tree, it may be 
saved by cutting away only the 
diseased portion. In such cases 
remove all the dead wood and 
bark back into the bright wood 
and leave the wound smooth. The 
wound heals more readily if the 
bark about the edges is trimmed 
with a sharp knife held in making 
the cut at right angles to the 
branch. The lower part of the 
cut should come to a point like 
the bottom of a “V” in order to 
provide good drainage. This pre- 
caution makes the wound less li- 
able to heart rot. To make sure 
that the cankers are all removed, 
it is necessary to go over the orch- 
ard several times, approaching 
the trees from a different angle 
each time. 
2. Treat the wounds on the 
large limbs and trunks by disin- 
fecting them with a solution of 
corrosive sublimate made as fol- 
lows : one part corrosive sublim- 
ate to 1,000 parts water. Con- 
venient-sized tablets of corrosive 
sublimate may be obtained from 
any drug store with the directions 
for making the solution. Keep in 
glass jars or stone jugs because 
the solution corrodes metals. It 
is a deadly poison if taken intern- 
ally and must be kept from chil- 
dren and animals. After the 
wounds are dry, paint them with 
a good white lead and oil paint. 
If desired, a little lamp black may 
be added to the paint for the ap- 
pearance. 
3. Prune out new infections 
promptly and in case of suckers 
or small branches, cut a foot or 
more below the blackening of the 
bark because the bacteria work 
farther under the bark than its 
appearance indicates. It is espe- 
cially important to go over young 
orchards frequently to remove the 
blight before an epidemic has 
time to start. In case of a blight 
epidemic in blossoming orchards, 
the prompt removal of all blight- 
ed parts may be impractical. In 
such orchards, it is important to 
be sure that all hold-over cankers 
are destroyed. 
4. Disinfect the pruning tools 
after each cut by wiping them with 
a clean cloth wet in the corrosive 
sublimate solution. This destroys 
any blight bacteria that might be 
carried on the saw or knife. 
5. Burn blighted material 
promptly because in damp weather 
the bacteria remain alive in it for 
some time. 
Twig Blight and Canker 
6. Remove suckers on trunks and 
large branches as soon as they ap- 
pear; they are especially liable to 
blight and give rise to cankers and 
collar-blight forms of the disease. 
7. Avoid forcing sappy wood 
growth by too frequent cultivation 
or too heavy applications of ma- 
nure and nitrogenous fertilizers be- 
cause the blight bacteria work most 
rapidly and severely on such wood. 
8. Do not set Transcendent crab 
because it is especially susceptible 
to blight under Wisconsin eomL- 
tions. Yellow Transparent and 
some other Russion varieties are 
also more or less susceptible. 
9. Kill noxious insects which 
