CHAPTER IX. 
INSECTS AND DISEASES. 
This little book is so entirely elementary that we can 
give only one brief piece of advice about plant diseases, and 
that is to have none of them. 
Disease seldom or never troubles plants set in fresh soil 
in new frames or new houses, and this is one reason why 
beginners so often have ‘‘ good luck’’ at the outset, to be 
followed by ‘‘bad luck’’ in later years. Of course there is 
in reality no “‘luck’’ about it. The beginner works with 
wholesome surroundings. 
The disease called ‘‘ damping off,’’ which affects many 
under-glass crops, is supposed to be of fungous character. 
It mostly results from bad air. Free ventilation and cleanli- 
ness will usually prevent it; though it sometimes troubles 
plants in the open air. It is especially common in old frames 
or hot beds, near decaying boards, and in soil that has been 
previously used. Its prevention is possible, in the way indi- 
cated, but the death of the plant is sometimes our first notice 
of its presence in the bed. 
‘“‘Burning’’ of lettuce is also supposed to be a fungous 
disease, the result of improper management. ‘The lettuce 
decays at the heart, and is rendered worthless. Fresh soil is 
the best remedy, if other conditions (including ventilation) 
are not at fault. 
Aphides, or plant lice, can be destroyed with tobacco 
smoke or tobacco water, though it is sometimes difficult to 
kill these insets on the under side of lettuce leaves. It is 
well to see that the seedling plants (when transplanted) are 
free from the insects. Tobacco stems may be used among 
the lettuce plants. 
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