INSECTS AND DISEASES AND METHODS OF FIGHTING THEM

I use the term "methods of fighting" rather than the more usual one,
"remedies," because by both experience and study I am more and more
convinced that so long as the commercial fields of agriculture remain
in the present absolutely unorganized condition, and so long as the
gardener--home or otherwise--who cares to be neglectful and thus become
a breeder of all sorts of plant pests, is allowed so to do--just so
long we can achieve no remedy worth the name. When speaking of a remedy
in this connection we very frequently are putting the cart before the
horse, and refer to some means of prevention. Prevention is not only
the best, but often the only cure. This the gardener should always
remember.
This subject of plant enemies has not yet received the attention from
scientific investigators which other branches of horticulture have, and
it is altogether somewhat complicated.
Before taking up the various insects and diseases the following
analysis and list will enable the reader to get a general comprehension
of the whole matter.
Plant enemies are of two kinds--(1) insects, and (2) diseases. The
former are of two kinds, (a) insects which chew or eat the leaves or
fruit; (b) insects which suck the juices therefrom. The diseases also
are of two kinds--(a) those which result from the attack of some
fungus, or germ; (b) those which attack the whole organism of the plant
and are termed "constitutional." Concerning these latter practically
nothing is known.
It will be seen at once, of course, that the remedy to be used must
depend upon the nature of the enemy to be fought. We can therefore
reduce the matter to a simple classification, as follows: