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| Agriculture
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| Control of Fungus Diseases |
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Bordeaux and Burgundy mixtures have been found effective
in controlling a whole host of fungus diseases of plants. Normally
a 0.5 % to 1 % Bordeaux or Burgundy mixture applied at 2 to 3 week
intervals suffices to control most copper-susceptible fungi.
Generally once the fungus spores have alighted on the host plant and
penetrated the tissues it is difficult to control them. The principle
of control must in most cases depend on protection, ie preventing
the fungus spores from entering the host tissues. Copper fungicides
are noted for their tenacity and for this reason are much to be preferred
in areas of high rainfall. The simplest method of control is to apply
a protective coating of Bordeaux or Burgundy mixture (or other copper
fungicide) to the susceptible parts of the plant, so that spores alighting
on them come in contact with the protective film of copper and are
killed instantly. It is thus important to remember that the first
spraying must ideally be made just before the disease is expected
and continued at intervals throughout the susceptible period. For
this reason it is important to take advantage of the early warning
schemes which are in operation to ensure greater accuracy of the timing
of the first spraying. It must also be remembered that fungi are plants
and that control measures that will kill them may not always leave
the host plant unaffected. The use of too concentrated a fungicide
mixture must therefore be guarded against, particularly for the early
sprays. |
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