ry, 
- J 
4 
MINNESOTA STATE HORTICULTURAL SOCIETY. 15 
Now, while I do not think any of the theories suggested by the 
names fire-blight, insect blight, frozen sap-blight, sufficient explana- 
tion of the cause, I think it quite probable that anything which 
tends to an unhealthy growth may be a predisposing cause, while 
something else is the immediate cause. In order to introduce you 
to this supposed immediate cause, I take the liberty of a slight di- 
gression. wit 
_Far down in the scale of vegetable life there is a group of plants 
called Fungi, which despite the exceeding minuteness of many of its 
members, exercises a very important office in nature and upon hu- 
man life and industry. Some of these plants render very important 
services, as seen in yeast, the value of which depends on the multi- 
plication and growth of one of these plants; also seen in the manu- 
facture of vinegar and all kinds of fermentation, and the curing of 
cheese. Others, again, cause great trouble and injury. Smut in 
wheat is caused by one, ergot in rye by another, mildew of the grape 
by a third, rust by a fourth, bread-mould by a fifth, and so on. 
Many of these plants produce spores, which answer to seeds in 
higher plants, in immense numbers. ‘These spores are very minute, 
float easily in the air, and often they possess great hardiness and 
vitality, some of them withstanding the boiling point of water and 
several degrees of frost. Of one it is estimated that a single square 
inch of leaf affected by it will produce 3,000,000 zoospores, a kind 
of seed or fruit peculiar to it. Of another it is estimated that in 
24 hours a single spore will produce 20,000,000 of individuals. In 
germinating, these spores send out a net work of thread like fila- 
ments, and these in turn produce spores again, but sometimes the 
plant produces two or three forms of fruit before bearing its own 
true spores, and sometimes these filaments grow a considerable 
time without producing fruit of any kind. But in order that these 
spores may grow at all they must find suitable food and suitable 
conditions of moisture and temperature. Warm and moist condi- 
tions are in general most favorable. 
But whether this or something else be the true cause of blight, no 
patent preventive or remedy is known for it. The best that can 
be advised by way of prevention is to place the tree under the best 
conditions and keep it in the most healthy growing habit possible. 
Place the tree in a moist but not a wet soil. Discourage very early 
spring, and especially late fall growths, and seek after only a mode- 
rate growth each year. 
Probably the best mode of procedure when the disease appears in 
the nursery is to take out the affected trees as soon as discovered, 
and burn them, to prevent as muchas possible the spread of the 
disease. When it appears in large trees cut out the branches one to 
three feet below the affected point, and burn the excised portion, 
Among possible remedies and preventives may be mentioned 
washing trunks and branches with solution of copperas, or with car- 
bolic acid. A friend on the appearance of blight among his pear 
trees immediately ceases cultivation, letting the ground.grow up to 
grass, and thinks he checks the disease in this way. 
In view of these facts relating to Fungi in general, it appears 
quite possible that the growth of some of these plants should be the 
