Prevention Of Plant Disease
In the last two sections you have learned something of the nature of
those fungi and bacteria that cause disease in animals and plants. Now
let us see how we can use this knowledge to lessen the diseases of our
crops. Farmers lose through plant diseases much that could be saved by
First, you must remember that every diseased fruit, twig, or leaf bears
millions of spores. These must be destroyed by burning. They must not be
allowed to lie about and spread the disease in the spring. See that
decayed fruit in the bin or on the trees is destroyed in the same
manner. Never throw decayed fruit into the garden or orchard, as it may
cause disease the following year.
Second, you can often kill spores on seeds before they are planted and
thus prevent the development of the fungus (see pp. 134-137).
Third, often the foliage of the plant can be sprayed with a poison that
will prevent the germination of the spores (see pp. 138-140).
Fourth, some varieties of plants resist disease much more stoutly than
others. We may often select the resistant form to great advantage (see
Fifth, after big limbs are pruned off, decay often sets in at the wound.
This decay may be prevented by coating the cut surface with paint, tar,
or some other substance that will not allow spores to enter the wound or
to germinate there.
Sixth, it frequently happens that the spore or fungus remains in the
soil. This is true in the cotton wilt, and the remedy is so to rotate
crops that the diseased land is not used again for this crop until the
spores or fungi have died.
Next: Some Special Plant Diseases
Previous: Yeast And Bacteria