The evening times. [volume] (Washington, D.C.) 1895-1902, 1901-03-13

Best Advantage 10 Protect FOIiaGe. /
Three Methods of Application.
Time for the Inspection of Plants.
g J. NarIatt, first assistant entomoIo-
gist OF the Department OF Agriculture, /
has written treatise on important In
secticides, which was issued yesterday
in bulletin form. 1t gives brief directions
concerning a few of the insecticide
agents having the widest range and at
tended with the greatest usefulness, econ
orny. and ease of application
Regarding insecticides for external bit
ing insects The bulletin says: The ar
scnfcaI compounds have suppIanted. prac-
ticaiIy. all other substances for the in
sects falling under this heading The two
arsenIcaIs IN most common use and OBJ
tainal,Ge everywhere. are Paris green
and London purple. The other two ARISEN
icals mentioned. Scheele's green anG ar
senate of lead. are less known and not
so easily obtainable. but in some respects
are better than the aforementioned pois-
ons as viii be shown later The use Of
powdered white arsenic is not recon-
neuded, on account of its great liability
TO scald foliage. rs well as for the fact
that it is apt to be mistaken for harmless
substances The arsenicais mentioned
have the following characteristics:
Paris green is definite chemical com
pound Of arsenic, copper. and aceJic acid
Oknown as the aceto-arsenite of copper
and should have uniform composition 1t
is {. rather coarse powder. or. more prop
erIy speaking, crystal, and settles rapidly
in water. which IS its greatest fault Its
| excessive cost. about 20 cents a pound, is
! due to its being crystalIized with acetic
| acid, making it a more brilliant pigment.
! but givin= it a coarse grain and rendering
! it a much poorer insecticide-
! ''Scheele's green is similar to Paris green
| in color and differs from II only in lack
! ing acetic acid; in other words, it is
! simple arsenite of copper. II is d much
/ finer powder than Paris green, and there
! fore more easily kept in suspension. and
/ has the additional advantage of costing
I only about half as much per pound When
/ properly washed and prepared by the
/ manufacturers ii is less harmful to foliage
! even than Paris green, IS quicker in eff
| feet. and should supplant the latter as an
! insecucide- 1t is used in the same way
and at about the same strength As Paris
/ green and London purple
/ London purple is a waste product in
| the manufacture Of aniIine dyes and con-
| tains a number OF substances. chief Of
which are arsenic and lime. 1t is quite
( variable in the amount of arsenic and is
! not so effective G-s the green Doisons and
is much more apt 10 sCald unless mixed
i with lime 1t comes as d very fine powder,
and is more easily kept in Suspension than
/ Paris green. Il costs about IL cents
| pound.
| --Arsenate Of lead is prepared by com
! bining, approximately, , parts Of the ar
| SENATE OF soda with parts of the acetate
/ of lead (white sugar of Lead in water
! These substances when puIverized unite
! readily and form white pTecitpate.
| which IS more easily kept suspended III
water than any Of the other pOiSouS-
! Bought wholesale, the cFyStalliZed acct
| ate Of lead costs about IA cents a pound
tor the uncrystallized brown sugar Of
| lead, cents, and the arsenate of soda .
| cents pound. 1t is now on the market
as a dry powder, white or cOiOred with
/ dye, ready for immediate use, costing
/ about 10 cents a pound, and also paste
/ form. ArSeHate Of lead may be used at
! any strength froR5 , to Is pounds TO the
! gallons OF Wate- without injury 10 the
/ foliage. and IN this respect Is much safer
! on delicate plants than any other arsen-
+! zeal. Its use Is advised where excessive
! strengths are desirable or with delicate
: plants where scalding is otherwise liable
( TO result With this insecUicide there is
J an advantage in using the freshly pre-
: pared and wet mixture in that II gives
! more hlmy and adhering coating TO foil
/ age, the same fneness NOT being secured
/ when il has been dried and repulyeriZed-
/ In point OF solubiIty and correspond
! ing danger of Scalding the foliage. these
/ arsenicals fall in the following order the
/ least soluble first ATSenate Of lead.
( Scheele's green, Paris green, and London
/ purple The difference between the first
! three is net great in the particulars noted
! nor also in point Of effectiveness against
! larvae, OF other Insects London purple
/ IS ordinarily less effective
/ There are three principal methods Of
/ applying arSenicalS. The wet method
which consists in using these poisons ia
! water IN the form Of spray. is the stand
/ ard means, secures results at least eE-
! pense, and IS the only practical method
/ Of protecting fruit and shade trees The
dry application Of these pOiSOns IN the
form Of powder, which is busted over
plants. IS more popular a means
! against the cotton worm IN the South.
! where the rapIc'ty OF treatment possible
/ by this method. and its cheapness,
give Il value against this IN
( sect IN the practical treatment of which
prompt and economical action are the IS
/ sentlals- This method i also feasible for
/ any low-ErOWlng crop such as the potato.
/ young ca5baGeS- OF other plants not to be
/ Immediately employed as food The third
( n.eilou consists IA the use OF the arse
/ meals IN the form Of poisoned bats, and
/ Is particularly aVailab5- - -.-~tt- ---@eotS
/ as cuIWorTns- wIreworrns, and Iocusts in
/ The importance Of prcrnptness in the
( treatment or plants attacked by insects
( cannot be too strongly insisted uDOn.
I The remedy often becomes useless # long
! deferred the injury having already been
/ accomplished or gone beyond repair II
I by careful inspection of plants from
/ time. 10 time, the injury can be detected
at the very outset treatment * com
/ DaratNely easy. and the result much
more satisfactory. Preventive work
therefore should be done as much as
possible, rather than waiting for the rem
edial treatment later; the effort being 70
! foreStali any serious injury rather than
TO patch up damage which neglect has
allowed 10 become considerable
I 1T may often happen that the amount
Of work in q community is sufficient 70
induce one OF more persons to undertake
I the treatment Of plants at 4 given charge
/ per tree or per gallon of the insecticiie
employed Where this is the case. and
the contracting parties are evidently ex-
/ perienced aud capable it is frequently
more economical in the end 10 employ
such experienced persons. especially when
| a guarantee Is given, rather than attempt
70 DO the work ones self with the at
| tending difficulty Of preparing insecticides
and securing apparatus for work on d
conpa ratIVely small scale In California
| this is q common practice, and also in
! some Of our Eastern cities, and has work
| ed eXcelieTtiy-
Mr.. CLEVELAND STARTS HOME.
| The Ex-PresidenT Talks Freely on