522 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
June  '23.  1H98. 
this  pest  passed  over  in  the  “  set,”  and  was  practically  out  of  reach  by 
any  dressing  applied  to  the  land. 
Hydrofluoric  Acid. 
It  may  be  sta'ed  that  this  substance  is  prepared  by  decomposing  fluor 
spar  with  sulphuric  acid  in  a  retort  ot  lead,  the  acid  distilling  oyer  being 
collected  in  a  leaden,  platinum,  or  gutta-percha  bottle.  It  is  a  very 
powerfully  corrosive  substance,  and  very  dangerous  to  have  anything  to 
do  with,  even  in  the  aqueous  solution,  being  then  very  destructive  to 
animal  and  vegetable  tissues,  and  its  vapour  irrespirable.  In  this  state  it 
reacts  with  silica  to  form  silicic- fluoride — a  transparent  colourless  gas, 
decomposed  by  water.  This  will  be  enough  to  connect  the  substances 
known  as  fluorine  (F)  and  hydrofluoric  acid  (Hb)  with  the  silico- 
fluoride  noticed  in  the  Journal  of  Horticulture  by  Mr.  W.  ^lills,  October 
21st,  1897,  page  391,  and  put  forward  by  him  as  a  germicide. 
Fluor  spar,  or  Derbyshire  spar,  so  far  as  I  know,  has  not  been  used 
as  a  general  dressing  for  laud,  though  beds  of  it  at  Alton  ISloor  and 
Caslleton,  in  Fngland,  and  extensive  veins  in  the  United  States,  exist. 
The  use  of  it,  however,  for  the  experimental  purposes  already  foreshowed 
were  satisfactory,  the  rate  of  application  in  powder  being  1  stone  per 
rod,  1  ton  per  acre.  The  acid  I  have  not  used,  but  have  found  fluoride  of 
potassium  a  powerful  fungicide  and  insecticide  at  a  strength  of  I  part  in 
1000  parts  of  water,  or  1  fluid  ounce  to  gallons,  this  being  strong 
enough  for  the  foliage  of  most  plants,  or  as  much  as  it  will  bear  without 
injury.  The  roots  will  endure  a  greater  strength,  but  plants  vary  greatly 
in  their  susceptibility  or  otherwise  to  injury. 
SiLICO-FLUORIDES. 
Mr.  Mills,  on  the  page  previously  quoted,  gave  instructions  for 
preparing  silico-fluofide  of  ammonium,  and  in  the  page  following  a 
communication  was  also  given  by  another  authority  on  the  preparation 
of  the  silico- fluorides  from  Derbyshire  spar.  The  substances  are  not  new 
to  me.  I  have  had  long  acquaintance  with  them,  except  that  of  the 
silico-fluoride  of  ammonium  fNH^jaSiFg,  which  easily  dissolves  in  water. 
Silico-Huoride  of  potassium,  K.^SiFg,  or  “  Salufer,”  silico-fluoride  of 
sodium.  NajSiFg,  and  silico-fluoride  of  calcium,  CaSiFg,  were  also  sent 
me  by  Mr.  Mills,  with  fluor-hydrate  of  sodium,  NaFgH.^O. 
In  bringing  to  bear  upon  these  what  little  chemical  knowledge  I  could, 
there  were  two  ways  in  which  I  thought  one  or  other  of  the  preparations 
likely  to  prove  valuable  from  the  standpoint  of  utility — namely,  (1)  as  a 
pest  destroyer,  and  (’2)  as  a  plant  nutrient — a  combination  which  I  hold 
to  be  imperative  in  these  times  of  severe  competition  ;  therefore  I  merely 
satisfied  myself  of  the  killing  value  of  the  silico-fluoride  of  sodium  and 
the  fluor-hydrate  of  sodium,  thus  narrowing  the  thing  down  to  the 
ammonia,  potash,  and  lime  preparations. 
Having  a  study  of  eelworms  in  hand,  and  fine  specimens  to  operate  on, 
I  subjected  a  few  to  various  solutions  in  water  and  in  soil,  also  in  the 
infested  tissues  of  plants.  The  results  were  very  disastrous  to  these, 
and  I  came  to  the  conclusion,  rightly  or  wrongly,  that  the  preparations 
were  not  suitable  for  use  on  the  living  parts  of  plants,  especially  foliage. 
This  would,  perhaps,  have  led  many  cultivators  to  abandon  the  articles. 
I,  however,  found  that  1  oz.  of  either  preparation  per  square  yard  would 
kill  eelworms  in  the  soil  without  injuring  this  for  the  purpose  of  plant 
growth. 
The  matter  was  thus  resolved  into  a  very  simple  affair,  as  the 
preparation,  in  the  finest  possible  powder,  could  be  used  before  sowing 
seeds  or  setting  plants  as  a  disinfectant  and  fertiliser  at  the  rate  of 
302^  lbs.  per  acre,  30i  oz.  per  rod,  or  1  oz.  per  square  yard,  leaving  on 
the  surface  or  only  very  lightly  harrowing  or  raking  in,  as  in  the 
operations  of  drilling  in  seed.  In  no  case  should  the  substance  come 
into  contact  with  the  seed  or  plant  in  the  dry  or  powdered  form.  If 
desired,  the  article  could  be  used  in  solution,  1  oz.  to  1  gallon  of  water, 
and  this  quantity  applied  per  square  yard. 
An  Interesting  Trio. 
The  three  articles — (1)  silico-fluoride  of  ammonium,  (2)  silico-fluoride  of 
potassium,  (3)  silico-Jluoride  of  calcium — killed  eelworms,  whiteworms,  and 
slugs  in  the  experimental  plats,  as  ascertained  by  microscopic  examination 
of  soils  and  soil- waters,  and  of  the  three  substances  the  silico-fluoride 
of  ammonium  most  benefited  the  plants,  these  being  selected  of  kinds 
the  most  liable  to  eelworm  attacks  in  the  several  forms,  such  as  stem- 
eelworm  (Tylenchus  devastatrix)  on  Clover  and  Onions  ;  root-stem  eelworm 
(T.  obtusus)  on  Cucumbers  and  Vines  ;  root-knot  eelworm  (Heterodera 
radicicola)  on  Tomatoes,  and  segging  eelworm  (H.  Schachti)  on  Hops 
and  Sugar  Beet.  These  pests,  every  one,  lead  free  as  well  as  parasitic 
modes  of  life,  and  the  time  to  act  upon  them  effectively  is  during  their 
existence  as  eggs  or  larvte  while  bathed  in  the  organic  solutions  of  the 
soil,  and  on  which  they  unquestionably  subsist  in  free  state,  being 
invariably  associated  with  the  debris  of  crops  or  vegetable  remains  decay¬ 
ing  or  decomposed. 
On  these  points  I  have  thoroughly  satisfied  myself  by  repeated 
investigations,  and  also  that  the  time  to  destroy  eelworms,  'whiteworms 
and  slugs  is  when  the  land  is  bare.  It  can  be  done  by  lime,  kainit, 
and  nitrate  of  soda  in  a  slow  manner,  in  conjunction  with  thorough 
cultivation  and  due  regard  to  the  rotation  of  crops.  About  that  there  can 
be  no  question,  for  most  ailments  have  origin  in  cultural  errors  and 
mistakes  or  procedure  on  lines  antagonistic  to  the  laws  of  health  required 
by  and  essential  to  the  growth,  development,  and  maturity  of  the  particular 
plant. 
Prevention,  not  cure,  should  be  the  great  objective  of  cultivators.  To 
prevent  any  disease  caused  by  vegetable  or  animal  parasite  means  must 
be  taken  to  kill  the  spores  or  eggs.  This  can  be  done  in  various  ways, 
invariably  whilst  outward  or  exterior  of  the  plant,  for  nothing  applied 
externally  can  have  any  effect  on  an  organism  in  living  tissues  without 
absorption  into  them,  and  then  the  substance  may  prove  as  deleterious  to 
the  host  as  destructive  to  the  parasite.  That  marks  the  difference  between 
prevention  and  remedy.  If  eelworms,  whiteworms,  or  slugs  are  in  the 
soil  the  time  to  kill  them  is  when  there  is  no  danger  of  prejudicing  the 
current  or  proposed  crop.  Silico-fluoride  of  ammonium  can  be  used  much 
more  freely  then  than  when  the  land  is  under  crop ;  but  I  consider, 
according  to  ihe  experimental  data,  that  the  amount  quoted  would  be 
sufficient  for  general  purposes,  or  in  bad  cases  it  could  be  doubled,  this 
being  matter  for  further  investigation  ;  suffice  at  present  that  the  strength 
named  for  killing  the  pests  be  given  as  found. 
Action  and  Results. 
The  silico-fluoride  of  ammonium  dissolves  in  rain  water,  and  at  a 
strength  of  1  oz.  to  1  gallon  of  water  kills  eelworm  in  a  short  time.  It 
does  not  appear  to  injure  the  roots  of  Tomatoes  when  applied  to  the  soil, 
as  in  an  ordinary  watering,  with  the  soil  in  a  moderately  moist  condition 
when  the  solution  is  supplied.  At  the  strength  quoted  it  seems  too 
strong  for  Cucumbers,  but  a  solution  of^l  oz.  to  gallon  of  water  had  no 
injurious  effect  on  the  roots.  At  that  strength,  1  in  240,  the  solution  also 
kills  eelworms,  but  requires  a  longer  time.  In  both  cases  the  eelworms 
collapse  in  the  tissues,  and  these  also  succumb.  That  is  where  the 
difficulty  comes  in — nothing  will  restore  destroyed  tissues.  The  plants 
may  die,  or  they  may  live  after  treatment,  for  all  depends  upon  the 
extent  of  the  damage  inflicted  by  the  eelworm,  and  possibly  also  by 
the  deleterious  action  of  the  solution  on  the  cells  in  contact  with  tha 
damaged  parts.  The  latter  are  quickly  saturated  by  the  solution,  but 
that  of  imbibition  by  adjacent  living  cells  is  quite  another  matter,  and 
depends  partly  on  the  plant  itself  and  in  part  on  the  substance. 
The  action  of  the  silico-fluoride  of  ammonium  is  corrosive.  It  kills 
pests  by  that  process.  The  effect  on  slugs  is  a  sight  to  see  once  only, 
and  never  desire  to  behold  again,  for  they  simply  appear  to  boil  by  the 
chemical  action  of  the  powder.  Eelworms  perform  their  graceful 
evolutions  in  the  vain  endeavour  to  escap’e,  and  soon  assume  needle  form. 
Whiteworms  (Enchytrmus  sp.)  seldom  make  more  than  a  wriggle  to 
right  and  left,  and  die.  In  a  1  in  1000  solution,  1  oz.  silico-fluoride  of 
ammonium  to  6,}  gallons  of  water,  the  pests  named  succumb  in  the 
course  of  tithe,  but  whether  that  would  suffice  as  a  general  preventive, 
applied  in  the  ordinary  course  of  watering,  remains  to  be  tested,  and  the 
most  that  I  am  prepared  to  say  is  that  it  would  probably  answer  that 
purpose,  and  also  as  a  repressive  measure  in  the  early  stages  of  attack. 
This  never  occurs  when  the  free  eelworms  are  bathed  in  a  solution  hurtful 
to  them,  as  they  make  '*  tracks  ”  away  from  such  soil  as  fast  as  possible. 
Manurial  Properties  and  Cost. 
Of  the  value  of  the , article,  silico-fluoride  of  ammonium,  as  a  manurey 
it  may  be  said  that  it  contains  over  19  percent,  of  ammonia,  therefore 
almost  equal  in  that  respect  to  ordinary  sulphate  of  ammonia,  and  while 
the  land  would  be  disinfected  by  a  suitable  top-dressing,  and  practically 
freed  from  pests,  the  ammonia  would  remain  for  the  benefit  of  the  crop. 
According  to  Mr.  Mills’  former  article  the  cost  would  be  £1  per  cwt.,  or 
10s.  cost  for  killing  the  eelworm,  and  10s.  value  as  manure,  per  each 
cwt.  applied.  On  this  point,  however,  time  only  can  give  anything 
warrantable,  and  experiments  in  that  direction  must  rest  with  cultivators. 
The  silico-fluoride  of  potassium  has,  so  far  as  I  have  tested,  more 
decisively  anti-fungoid  properties  than  the  ammonium  preparation,  also 
that  of  calcium,  but  the  sodium,  if  anything,  tends  to  favour  cr^  ptogamous 
parasites  by  its  action  on  the  tissues  of  the  hosts.  What  would  be  the 
difference  in  cost  of  silico-fluoride  of  ammonium  over  the  silico- fluorides 
of  potassium  and  calcium  I  do  not  know.  Perhaps  Mr.  Mills  will  supply 
particulars  in  those  respects.  I  shall  not  continue  further  experiments  at 
present,  as  my  material  has  become  exhausted,  the  eelworms  having 
departed — I  may  say  that  the  silico-fluorides  appear  to  advantage  in  the 
experiments  as  disinfectants  of  land  foul  with  root-pests.  In  other 
respects  the  articles  would  probably  usefully  aid  the  plant  by  fortifying 
it  with  material  resistive  of  invasion  by  enemies  ;  at  least  such  are  the 
deductions  from  the  experiments. — G.  Abbey. 
CLEANSING  WALL  TREES. 
Efforts  must  be  made  to  cleanse  wall  trees  if  the  shoots  are  infested 
with  black  or  green  aphis.  Cherries,  Plums,  Peaches,  Nectarines,  and 
Apricots  are  the  most  liable  to  attacks  from  these  insects.  Cold  winds 
and  checks  to  growth,  as  well  as  lack  of  moisture  for  the  root  system,  are 
conducive  of  attack.  In  cold,  dull  weather  the  syringe  or  water  engine 
is  not  employed  so  freely  on  wall  trees,  hence  insects  gain  a  foothold  and 
increase  freely  under  undisturbed  conditions. 
Dusting  with  tobacco  powder  is  efficacious  when  the  pests  are  first 
noticed.  On  becoming  a  numerous  colony,  a  strong  application  of  some 
approved  insecticide  is  needed.  A  bitter  solution  not  only  destroys  them, 
but  renders  the  foliage  distasteful  to  fresh  broods  seeking  to  become 
established.  Quassia  chips  boiled  and  the  solution  combined  with  dis¬ 
solved  softsoap,  forms  a  serviceable  mixture,  but  it  is  not  superior  to  the 
prepared  quassia  extract  which  can  be  procured  ready  for  use,  only 
requiring  mixing  with  water  at  the  rate  of  20  gallons  of  water  to  a  quart 
of  extract. 
It  is  important  that  Cherry  trees  be  freed  from  these  pests  before  the 
fruit  commences  colouring,  and  all  trees  infested  are  better  for  being 
cleansed  as  soon  as  possible.  It  is  often  delayed  too  long  with  disastrous 
results. — A  Kentish  Gardener. 
