﻿EXPERIMENTS 
  FOR 
  CONTROL. 
  

  

  21 
  

  

  spider 
  could 
  be 
  easily 
  controlled; 
  that 
  sulphur 
  dusted 
  or 
  blown 
  onto 
  

   the 
  vines 
  would 
  soon 
  check 
  their 
  progress. 
  General 
  observations 
  

   made 
  in 
  the 
  infested 
  fields 
  that 
  were 
  thoroughly 
  dusted 
  with 
  finely 
  

   powdered 
  sulphur, 
  however, 
  lead 
  the 
  writer 
  to 
  believe 
  that 
  dry 
  

   sulphur 
  is 
  of 
  no 
  value 
  whatever 
  in 
  checking 
  the 
  ravages 
  of 
  this 
  mite 
  

   upon 
  hops. 
  This 
  point 
  was 
  most 
  conclusively 
  proved, 
  as 
  will 
  be 
  seen 
  

   from 
  the 
  following 
  data. 
  

  

  In 
  testing 
  the 
  efficiency 
  of 
  this 
  material 
  upon 
  the 
  mites, 
  all 
  the 
  

   available 
  forms 
  of 
  dry 
  sulphur 
  were 
  purchased 
  and 
  a 
  precipitated 
  form 
  

   was 
  prepared 
  by 
  treating 
  a 
  lime-sulphur 
  solution 
  with 
  hydrochloric 
  

   acid. 
  These 
  sulphurs 
  were 
  applied 
  in 
  the 
  form 
  of 
  dust 
  (PI. 
  Ill, 
  fig. 
  2) 
  

   and 
  also 
  with 
  water 
  as 
  a/' 
  wet 
  spray." 
  Table 
  No. 
  Ill 
  gives 
  results 
  

   which 
  were 
  obtained 
  from 
  tag 
  counts 
  taken 
  at 
  various 
  times 
  during 
  

   the 
  season 
  of 
  1911 
  and 
  1912. 
  

  

  Table 
  III. 
  — 
  Negative 
  results 
  produced 
  by 
  sulphur 
  in 
  various 
  forms 
  used 
  against 
  the 
  

  

  red 
  spider 
  on 
  hops. 
  

  

  Date. 
  

  

  1911. 
  

   June 
  30 
  

  

  July 
  15 
  

   18 
  

  

  1912. 
  

   July 
  10 
  

  

  Material. 
  

  

  Precipitated 
  sulphur, 
  10 
  pounds; 
  

  

  flour 
  paste, 
  4 
  pounds; 
  water, 
  100 
  

  

  gallons 
  

  

  Flowers 
  of 
  sulphur, 
  20 
  pounds; 
  

  

  water, 
  100 
  gallons 
  

  

  Precipitated 
  sulphur, 
  10 
  pounds; 
  

  

  water, 
  100 
  gallons 
  

  

  do 
  

  

  Precipitated 
  sulphur 
  dust, 
  applied 
  

  

  dry 
  

  

  Precipitated 
  sulphur 
  dust. 
  

  

  

  Num- 
  

  

  Per 
  

  

  Days 
  

   be- 
  

   tween 
  

   appli- 
  

   cation 
  

   and 
  

   third 
  

   count. 
  

  

  

  

  Num- 
  

  

  ber 
  of 
  

  

  cent 
  of 
  

  

  Num- 
  

  

  

  ber 
  of 
  

  

  mites 
  

  

  mites 
  

  

  ber 
  of 
  

  

  In- 
  

  

  mites 
  

  

  killed 
  

  

  killed 
  

  

  mites, 
  

  

  crease 
  

  

  present 
  

  

  by 
  ap- 
  

  

  by 
  ap- 
  

  

  third 
  

  

  of 
  mites. 
  

  

  before. 
  

  

  plica- 
  

  

  plica- 
  

  

  count. 
  

  

  

  

  tion. 
  

  

  tion. 
  

  

  

  

  271 
  

   201 
  

  

  

  

  10 
  

   26 
  

  

  282 
  

   1,458 
  

  

  11 
  

   1,257 
  

  

  61 
  

  

  69.7 
  

  

  264 
  

  

  146 
  

  

  55.3 
  

  

  21 
  

  

  1,533 
  

  

  1,269 
  

  

  305 
  

  

  163 
  

  

  53.4 
  

  

  0) 
  

  

  C 
  1 
  ) 
  

  

  C 
  1 
  ) 
  

  

  560 
  

  

  638 
  

  

  

  

  21 
  

   30 
  

  

  670 
  

   1,198 
  

  

  110 
  

   560 
  

  

  

  

  

  

  Per 
  

  

  cent 
  of 
  

  

  in- 
  

   crease. 
  

  

  4.06 
  

   625. 
  00 
  

  

  19.64 
  

   87.77 
  

  

  1 
  Tags 
  lost 
  after 
  second 
  count. 
  

   Mites 
  of 
  all 
  ages 
  (larvae, 
  nymphs, 
  and 
  adults) 
  were 
  observed 
  from 
  time 
  to 
  time 
  on 
  the 
  tagged 
  leaves. 
  

  

  This 
  table 
  definitely 
  illustrates 
  the 
  inefficiency 
  of 
  sulphur 
  in 
  con- 
  

   trolling 
  the 
  red 
  spider 
  on 
  hops. 
  It 
  will 
  be 
  noted 
  that 
  a 
  certain 
  

   percentage 
  of 
  mites 
  was 
  killed 
  or 
  washed 
  off 
  by 
  the 
  spray, 
  but 
  the 
  

   increase 
  which 
  followed 
  proves 
  definitely 
  that 
  sulphur 
  in 
  the 
  dry 
  

   form 
  has 
  little 
  or 
  no 
  effect 
  upon 
  the 
  mites. 
  Observations 
  in 
  fields 
  

   where 
  sulphur 
  had 
  been 
  applied 
  by 
  hand 
  and 
  by 
  a 
  traction 
  dust 
  

   machine 
  also 
  bore 
  out 
  this 
  statement. 
  In 
  some 
  cases 
  there 
  were 
  

   few 
  mites 
  upon 
  the 
  sulphured 
  vines, 
  and 
  growers 
  claimed 
  that 
  the 
  

   sulphur 
  had 
  destroyed 
  the 
  mites. 
  Near-by 
  unsulphured 
  foliage, 
  

   however, 
  was 
  invariably 
  found 
  to 
  be 
  as 
  free 
  from 
  mites 
  as 
  the 
  "sul- 
  

   phured" 
  vines, 
  and 
  this 
  assumption 
  did 
  not 
  hold. 
  

  

  Sulphur 
  as 
  a 
  control 
  of 
  the 
  red 
  spider 
  on 
  hops 
  has 
  been 
  tested 
  and 
  

   found 
  wanting 
  and 
  is 
  superseded 
  by 
  the 
  contact 
  insecticides. 
  

  

  