﻿543 
  

  

  a 
  serious 
  blow 
  upon 
  the 
  agricultural 
  interests 
  of 
  the 
  State. 
  The 
  

   discovery 
  that 
  it 
  thrives 
  on 
  pecan, 
  mulberry 
  and 
  a 
  number 
  of 
  previously 
  

   unrecorded 
  host 
  plants 
  makes 
  it 
  especially 
  dangerous 
  ; 
  should 
  it 
  

   gain 
  a 
  hold 
  on 
  cypress 
  and 
  pine, 
  on 
  which 
  it 
  is 
  said 
  to 
  hve, 
  the 
  timber 
  

   regions 
  of 
  the 
  State 
  would 
  be 
  endangered. 
  ^.j| 
  

  

  The 
  southern 
  corn 
  root 
  worm 
  {Diabrotica 
  l2-punctata) 
  has 
  been 
  

   studied, 
  on 
  account 
  of 
  its 
  prevalence 
  in 
  various 
  sections 
  of 
  the 
  State 
  

   during 
  the 
  spring 
  of 
  1913. 
  The 
  discovery 
  of 
  larval 
  borings 
  in 
  potato 
  

   tubers 
  revealed 
  a 
  new 
  habit 
  of 
  the 
  pest. 
  

  

  Tartar 
  (H. 
  V.). 
  Chemical 
  Investigations 
  on 
  Lime-Sulphur 
  Spray. 
  — 
  

   Oregon 
  Agric. 
  Expt. 
  Sta., 
  Corvallis, 
  Research 
  Bull. 
  3, 
  March 
  1914, 
  

   28 
  pp. 
  

  

  Lime-sulphur 
  is, 
  perhaps, 
  one 
  of 
  the 
  most 
  extensively 
  used 
  insecti- 
  

   cides, 
  and 
  there 
  is 
  a 
  very 
  large 
  amount 
  of 
  hterature 
  dealing 
  with 
  the 
  

   methods 
  of 
  preparation. 
  The 
  number 
  of 
  formulae 
  and 
  processes 
  of 
  

   preparation 
  is 
  also 
  very 
  great, 
  and 
  when 
  carefully 
  considered 
  the 
  

   results 
  of 
  its 
  use 
  do 
  not 
  show 
  that 
  uniformity 
  which 
  might 
  be 
  expected. 
  

   It 
  may 
  appear 
  to 
  be 
  a 
  simple 
  matter 
  to 
  boil 
  together, 
  for 
  a 
  given 
  time, 
  

   given 
  weights 
  of 
  lime 
  and 
  sulphur 
  in 
  a 
  given 
  quantity 
  of 
  water, 
  but 
  

   as 
  a 
  matter 
  of 
  fact 
  the 
  resulting 
  products 
  may 
  vary 
  very 
  considerably 
  

   in 
  chemical 
  composition 
  owing 
  to 
  differences 
  in 
  the 
  quality 
  of 
  the 
  hme, 
  

   the 
  physical 
  condition 
  of 
  the 
  sulphur, 
  the 
  exact 
  time 
  of 
  boihng, 
  and 
  

   other 
  variable 
  conditions. 
  Since 
  what 
  is 
  required 
  for 
  an 
  efficient 
  spray 
  

   is 
  a 
  compound 
  of 
  more 
  or 
  less 
  definite 
  chemical 
  constitution, 
  the 
  

   rough 
  and 
  ready 
  methods 
  generally 
  adopted 
  do 
  not 
  result 
  in 
  a 
  uniform 
  

   product. 
  

  

  R. 
  W. 
  Thatcher 
  (Bull. 
  76, 
  Agric. 
  Expt. 
  Sta., 
  Pullman, 
  Wash., 
  1906) 
  

   worked 
  out 
  the 
  composition 
  of 
  a 
  number 
  of 
  Hme-sulphur 
  solutions, 
  

   either 
  commercial 
  or 
  prepared 
  by 
  formula, 
  and 
  he 
  arrived 
  at 
  these 
  

   conclusions 
  : 
  — 
  

  

  The 
  hme-sulphur 
  wash 
  contains 
  two 
  soluble 
  compounds, 
  namely 
  

   calcium 
  pentasulphide 
  and 
  calcium 
  thiosulphate. 
  The 
  relative 
  

   amounts 
  of 
  these 
  present 
  in 
  the 
  sprays 
  prepared 
  by 
  any 
  of 
  the 
  common 
  

   formulae 
  are 
  practically 
  the 
  same, 
  regardless 
  of 
  the 
  proportions 
  of 
  

   ingredients 
  used 
  in 
  the 
  boihng, 
  except 
  in 
  cases 
  where 
  blue 
  vitriol 
  is 
  

   added 
  to 
  the 
  mixture. 
  The 
  amount 
  and 
  proportions 
  of 
  these 
  two 
  

   compounds 
  is 
  not 
  influenced 
  by 
  the 
  presence 
  or 
  absence 
  of 
  salt 
  in 
  the 
  

   mixture. 
  The 
  addition 
  of 
  copper 
  sulphate 
  to 
  the 
  mixture 
  simply 
  

   resulted 
  in 
  the 
  removal 
  of 
  an 
  equivalent 
  amount 
  of 
  the 
  pentasulphide 
  

   sulphur, 
  forming 
  an 
  insoluble 
  copper 
  sulphide, 
  which 
  was 
  probably 
  

   of 
  no 
  value 
  whatever 
  as 
  an 
  insecticide. 
  He 
  was 
  also 
  of 
  the 
  opinion 
  

   that 
  when 
  the 
  hme-sulphur 
  was 
  sprayed 
  on 
  to 
  the 
  trees 
  the 
  calcium 
  

   pentasulphide 
  decomposed 
  very 
  rapidly 
  under 
  the 
  influence 
  of 
  the 
  

   atmosphere 
  and 
  hberated 
  large 
  quantities 
  of 
  very 
  finely 
  divided 
  

   sulphur, 
  which 
  in 
  some 
  manner, 
  not 
  definitely 
  determined, 
  acts 
  as 
  a 
  

   powerful 
  insecticide 
  towards 
  scale-insects 
  ; 
  that 
  later 
  the 
  calcium 
  

   thiosulphate 
  also 
  decomposes, 
  slowly 
  hberating 
  more 
  free 
  sulphur 
  

   and 
  forming 
  calcium 
  sulphite, 
  which 
  probably 
  also 
  possesses 
  insecti- 
  

   cidal 
  properties. 
  Thus 
  the 
  measure 
  of 
  the 
  immediate 
  effectiveness 
  of 
  

   the 
  spray 
  is 
  the 
  amount 
  of 
  sulphur 
  as 
  pentasulphide 
  which 
  it 
  contains, 
  

   whilst 
  the 
  calcium 
  thiosulphate 
  is 
  responsible 
  for 
  the 
  well-known, 
  

   long-continued 
  insecticidal 
  effect. 
  

  

  