﻿686 
  

  

  are 
  of 
  little 
  use. 
  The 
  number 
  of 
  sprayings 
  must 
  be 
  increased, 
  but 
  

   lead 
  arsenate 
  is 
  costly. 
  An 
  examination 
  of 
  the 
  role 
  played 
  by 
  the 
  

   latter 
  has 
  led 
  the 
  author 
  to 
  discard 
  it 
  and 
  to 
  substitute 
  sodium 
  

   arsenate, 
  of 
  which 
  from 
  4| 
  to 
  6 
  J 
  oz., 
  costing 
  ^d. 
  to 
  Ic?., 
  were 
  added 
  to 
  

   every 
  20 
  gallons 
  of 
  the 
  Bordeaux 
  mixture, 
  which 
  was 
  sprayed 
  five 
  

   times 
  between 
  April 
  and 
  the 
  end 
  of 
  June. 
  The 
  resulting 
  arsenate 
  

   of 
  copper 
  was 
  quite 
  as 
  resistant 
  to 
  rain 
  as 
  the 
  costly 
  and 
  doubtful 
  

   arsenate 
  of 
  lead 
  ; 
  it 
  was 
  also 
  cheaper, 
  even 
  though 
  sprayed 
  every 
  12 
  

   or 
  14 
  days 
  ; 
  it 
  was 
  more 
  efficient, 
  through 
  being 
  appHed 
  over 
  a 
  longer 
  

   period 
  ; 
  and 
  its 
  use 
  allows 
  a 
  very 
  dangerous 
  substance 
  to 
  be 
  dispensed 
  

   with. 
  It 
  may 
  sometimes 
  happen 
  that 
  with 
  the 
  larger 
  dose 
  of 
  sodium 
  

   arsenate 
  (6 
  J 
  oz.) 
  the 
  spray 
  may 
  scorch 
  the 
  leaves. 
  This 
  is 
  due 
  to 
  

   its 
  being 
  alkaline, 
  and 
  a 
  slight 
  increase 
  of 
  the 
  sulphate 
  of 
  copper 
  up 
  

   to 
  6| 
  oz. 
  per 
  20 
  gallons 
  corrects 
  this 
  defect. 
  Arsenicals 
  are 
  ineffective 
  

   against 
  insect 
  enemies 
  after 
  blossoming, 
  and 
  nicotin 
  is 
  of 
  no 
  greater 
  

   value. 
  Heat 
  is 
  better, 
  hot 
  water 
  being 
  the 
  most 
  convenient 
  medium 
  

   [see 
  this 
  Review, 
  Ser. 
  A, 
  ii, 
  p. 
  444]. 
  In 
  the 
  spring 
  the 
  young 
  shoots 
  

   of 
  the 
  vine, 
  rose, 
  gooseberry, 
  wild 
  quince, 
  peach, 
  plum 
  and 
  cherry 
  

   resist 
  watering 
  with 
  hot 
  water 
  at 
  158°F., 
  the 
  slightly 
  withered 
  

   appearance 
  disappearing 
  on 
  the 
  next 
  day. 
  It 
  is 
  inadvisable 
  to 
  exceed 
  

   this 
  temperature 
  where 
  delicate 
  tissues, 
  such 
  as 
  the 
  stamens 
  of 
  fruit 
  

   blossoms, 
  are 
  concerned. 
  In 
  the 
  vine, 
  grapes 
  resist 
  a 
  temperature 
  

   up 
  to 
  168°F. 
  after 
  the 
  fruit 
  is 
  set, 
  as 
  also 
  do 
  the 
  older 
  stalks 
  and 
  leaves 
  ; 
  

   the 
  leaves 
  and 
  stalks 
  of 
  fruit 
  trees 
  also 
  remain 
  unaffected. 
  The 
  use 
  

   of 
  the 
  ordinary 
  knapsack-sprayers 
  containing 
  26 
  J 
  pints 
  is 
  recommended, 
  

   the 
  plants 
  being 
  well 
  watered 
  and 
  not 
  merely 
  sprayed. 
  When 
  dealing 
  

   with 
  a 
  few 
  plants, 
  17-| 
  pints 
  of 
  boiling 
  water 
  are 
  poured 
  into 
  the 
  

   sprayer 
  and 
  8| 
  pints 
  of 
  spring 
  or 
  river 
  Avater 
  at 
  a 
  temperature 
  of 
  from 
  

   59°F. 
  to 
  69°F. 
  are 
  added, 
  so 
  that 
  an 
  average 
  of 
  about 
  160°F. 
  results. 
  

   After 
  loss 
  by 
  radiation, 
  etc., 
  the 
  water 
  reaches 
  the 
  plant 
  at 
  a 
  tempe- 
  

   rature 
  of 
  149°F. 
  on 
  an 
  average. 
  When 
  dealing 
  with 
  entire 
  plots, 
  a 
  

   portable 
  boiler 
  is 
  used, 
  as 
  in 
  deahng 
  with 
  Sparganothis. 
  In 
  April, 
  when 
  

   the 
  shoots 
  are 
  from 
  6 
  to 
  12 
  inches 
  long, 
  hot 
  water 
  at 
  131°F. 
  will 
  kill 
  

   Sparganothis 
  larvae 
  in 
  half 
  a 
  minute, 
  and 
  they 
  also 
  die 
  if 
  in 
  contact 
  

   with 
  water 
  between 
  140°F. 
  and 
  150°F. 
  for 
  from 
  5 
  to 
  10 
  seconds. 
  When 
  

   the 
  vine 
  is 
  more 
  developed 
  and 
  Sparganothis 
  begins 
  to 
  be 
  present 
  in 
  its 
  

   web, 
  the 
  hot 
  water 
  easily 
  penetrates 
  if 
  the 
  watering 
  is 
  a 
  little 
  prolonged. 
  

   Both 
  Clysia 
  and 
  Polychrosis 
  yield 
  to 
  water 
  at 
  150°F. 
  so 
  long 
  as 
  they 
  

   are 
  not 
  inside 
  the 
  tissues. 
  In 
  any 
  case 
  this 
  method 
  will 
  destroy 
  

   large 
  numbers 
  of 
  first 
  generation 
  larvae. 
  So 
  far 
  as 
  observed, 
  Clysia 
  

   and 
  Polychrosis 
  eggs 
  aborted 
  through 
  the 
  action 
  of 
  heat. 
  Hot 
  water 
  

   at 
  150°F. 
  destroys 
  all 
  the 
  eggs 
  it 
  touches. 
  This 
  is 
  of 
  importance 
  as 
  

   regards 
  the 
  troublesome 
  summer 
  generations, 
  and 
  hot 
  water 
  treat- 
  

   ment 
  is 
  advisable 
  after 
  the 
  moths 
  have 
  oviposited. 
  In 
  nearly 
  all 
  

   cases, 
  plants 
  resist 
  the 
  action 
  of 
  hot 
  water 
  far 
  better 
  than 
  their 
  insect 
  

   or 
  cryptogamic 
  parasites. 
  Simultaneous 
  treatment 
  against 
  insects 
  

   and 
  mildew 
  is 
  easily 
  effected 
  by 
  using 
  water 
  at 
  160°F. 
  containing 
  

   1 
  per 
  cent, 
  of 
  neutral 
  acetate 
  of 
  copper, 
  and 
  the 
  use 
  of 
  hot 
  copper 
  

   solutions 
  against 
  mildew 
  is 
  most 
  advisable 
  on 
  account 
  of 
  their 
  great 
  

   wetting 
  power. 
  The 
  portable 
  boiler 
  used 
  produces 
  120 
  gallons 
  of 
  

   boiling 
  water 
  per 
  hour 
  ; 
  it 
  is 
  supplied 
  from 
  a 
  transportable 
  barrel 
  ; 
  

   an 
  extra 
  barrel 
  is 
  required 
  for 
  dissolving 
  the 
  neutral 
  acetate 
  of 
  copper, 
  

   and 
  knapsack 
  sprayers 
  of 
  26J 
  pints 
  capacity 
  are 
  carried 
  by 
  the 
  men. 
  

  

  