The citizen. (Frederick City, Md.) 1895-1923, 1905-03-31
PARIS GREEN SPRAY.
why 1t ScOrches-ERect on Vapious
Kinds of Foliage.

why III ScOrcheS-EHect on VARIOUS
Kinds of Foliage.
1t does not seem to have been gener-
ally recognized by entomologists and
chemists, says j. X. Haywood, that
there may be three conditions of paris
green which will cause a scorching Of
the foliage.
First.-There may be a certain
amount of arsenious oxide in paris
green over and above that combined
with the other constituents. This is
free" arsenious oxide, and until re
Gently it has been considered the only
cause of a scorching Of the foliage by
paris green.
Second.-The greens may be poorly
made, so that the constituents are very
loosely held together. When such
green's are brought in contact with wa
ter, especially water containing carbon
dioxide, they are soon broken up, and
arsenious oxide is set free. Even the
! best green's break up to some extent
under such conditions but the poorly
made greens decompose much more
i rapidly. Note, then, the effect of such
! green's upon the foliage First, the wa
ter of the spray would act at once on
the green and set arsenious oxide free;
| then carbon dioXide would dissolve in
/ the water and carry the decomposition
Of the green still further. But the mat
ter would not end here, for the rain
and dew both containing carbon di
oxide, would also act upon the green
and enough free arseniouS oxide would
soon collect to severely scorch the
/ foliage. This would of course take
place more slowly with even the best
green's, but unless the climatic condi
| tons We're very adverse not enough
free arsenious oxide would be apt to
accumulate at any one time to cause
any serious damage.
| Third.-The green may be extremely
fine. 1t is well known that even the
best greens when ground to very
fine powder and applied to the foliage
will scorch. This is doubtless due to
the fact that more surface is exposed
to the action of the water, which may
contain carbon dioXide, so that it's de.
composing action on the green is &C.
! tolerated, and enough free arseniouS
! oxide soon gathers to cause serious
damage.
| 1t is a very common occurrence to
secure commercial paris green that
scalds because of one of the first two
/ causes-i. e., either by reason Of the
/ presence of free arsenious oxide or be-
cause it is poorly manufactured-but
the writer has never found a CONNER
| cial sample Of green that scorched be
cause it was in too fine condition.
The Action on Different Trees.
Messrs. Craig and Weed of Ithaca,
! N. Y, obtained the following results in
spraying experiments:
OF the apple, pear, plum and peach
foliages the apple is injured the least,
the pear and plum are affected to about
the same degree, and the peach is in
! jured the most.
If only one application is made. paris
green containing per cent of free ar
senious oxide can be applied with safe
! " to apple trees. and with the addition
| or lime per cent may be present.
If only one application is made to
pear or plum trees. paris green con
tanning 8 per cent Of free arsenious
oxide can be applied with safety and
with the addition of lime per cent.
One application to peach trees OF
paris green containing 3 per cent Of
! free arsenious oxide cannot be made
with safety without the addition OF
time. With lime 4 per cent may be
/ nsed
Two applications will do more dam
age than a single one, and more injury
is apt to occur if the weather condi-
tons were normal previous to thN
spraying than If very dry weather oh.
| tAined