Disease in plantsWard, H. Marshall (Harry Marshall)
Science
Disease in plants
Ward, H. Marshall (Harry Marshall)
Plant diseases
If I were asked to sum up the most important result of the numerous
advances made during the past decade in agriculture and forestry, I
should reply--the clearer and wider recognition of the fact that the
plant itself is the centre of the subject, and not the soil, climate,
season, or other factors of its environment. Until comparatively recent
times it was the habit of farmers, foresters, planters, and gardeners,
all the world over, to look upon the plant as a mere item or as a
mysterious if important one in their calculations, and to regard the
soil as the chief factor in their studies.
Now all is changing, and the world is gradually awakening more and more
to the recognition of the truth that the soil and the clouds and the
atmosphere are merely reservoirs of more or less inert materials, from
which the living plant draws its supplies, and works them up, by means
of energy focussed from the sun, into new plant substance.
In other words, the more far-seeing pioneers of scientific agriculture
and forestry, etc., are recognising that agricultural chemistry is not
the be-all and end-all of agricultural science; but that, in place of
the study of the chemical analyses of dead soil, water, air, and
plant-remains, which has so long held sway, largely owing, I think, to
the influence of Liebig, the student should have his attention more
concentrated on the living plant itself and on the physiological actions
which make up its life. He must regard the living plant as a sort of
working machine--infinitely more complex than any machine made by man,
but a machine nevertheless--the purpose of which is to store up energy
from the sun, and so to add to our wealth on this planet, at the expense
of the extra-terrestrial universe.
It is not, be it noted, that the new study proposes to ignore or abandon
the old studies: modern physiology owes too much to the physics and
chemistry on which it is partly based, and to the labours of De
Saussure, Ingenhousz, Priestley, and others, for that. But it is that
the new study recognises that the central point, to which all views must
be focussed, is not the one that it was formerly supposed to be. The
student is still taught that the chemistry of soils yields valuable
information, and that lessons of importance are derived from comparisons
of the analyses of the ashes, etc., of plants; but he is no longer able
to cherish the hope, however remotely, that such studies solve his most
important problems.
Public-domain text, read in full here on John Shaqi.
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