﻿34 
  THE 
  BED 
  SPIDER 
  ON 
  HOPS 
  IN 
  CALIFORNIA. 
  

  

  Although 
  the 
  red-spider 
  injury 
  is 
  relatively 
  not 
  so 
  great 
  on 
  vines 
  

   invigorated 
  by 
  fertilization, 
  it 
  is 
  present 
  and 
  will 
  be 
  extensive 
  accord- 
  

   ing 
  to 
  the 
  severity 
  of 
  the 
  infestation. 
  

  

  Clean 
  culture. 
  — 
  In 
  September, 
  1911, 
  a 
  block 
  in 
  an 
  infested 
  hopyard 
  

   was 
  carefully 
  cleared 
  of 
  all 
  vegetation 
  in 
  an 
  attempt 
  to 
  destroy 
  all 
  

   of 
  the 
  mites 
  present. 
  When 
  examined 
  October 
  16, 
  however, 
  a 
  few 
  

   mites 
  were 
  observed 
  on 
  some 
  morning-glory 
  which 
  had 
  come 
  up 
  since 
  

   the 
  plat 
  was 
  cleared. 
  The 
  practice 
  of 
  clean 
  culture 
  is 
  very 
  important 
  

   and 
  has 
  a 
  great 
  influence 
  upon 
  an 
  infestation, 
  but 
  it 
  can 
  not 
  be 
  relied 
  

   upon 
  as 
  a 
  complete 
  control. 
  

  

  GENERAL 
  SUMMARY 
  WITH 
  RECOMMENDATIONS. 
  

  

  The 
  investigation 
  of 
  the 
  control 
  of 
  the 
  red 
  spider 
  on 
  hops 
  has 
  

   brought 
  out 
  the 
  following 
  points 
  : 
  

  

  Great 
  financial 
  loss 
  may 
  be 
  caused 
  by 
  the 
  red 
  spider. 
  

  

  The 
  mites 
  on 
  hops 
  are 
  not 
  affected 
  by 
  any 
  form 
  of 
  dry 
  sulphur, 
  but 
  

   are 
  readily 
  killed 
  by 
  several 
  contact 
  insecticides, 
  the 
  cheapest 
  and 
  

   most 
  convenient 
  of 
  which 
  are 
  flour 
  paste 
  (8-100) 
  or 
  a 
  combination 
  

   of 
  lime-sulphur, 
  36° 
  Baume 
  (1-100), 
  and 
  flour 
  paste 
  (4-100). 
  To 
  

   get 
  the 
  best 
  results 
  it 
  is 
  essential 
  that 
  the 
  vines 
  should 
  be 
  thoroughly 
  

   sprayed. 
  

  

  Stripping 
  the 
  vines 
  and 
  burning 
  the 
  leaves 
  is 
  an 
  excellent 
  measure, 
  

   but 
  should 
  not 
  be 
  entirely 
  relied 
  upon 
  as 
  a 
  complete 
  control. 
  When 
  

   the 
  infestation 
  is 
  severe 
  early 
  in 
  the 
  season 
  and 
  the 
  mites 
  are 
  above 
  

   the 
  point 
  of 
  stripping, 
  spraying 
  operations 
  should 
  be 
  commenced 
  as 
  

   soon 
  as 
  the 
  vines 
  are 
  stripped. 
  

  

  The 
  infested 
  area 
  must 
  be 
  thoroughly 
  and 
  rapidly 
  covered 
  and 
  must 
  

   be 
  sprayed 
  a 
  second 
  time, 
  7 
  or 
  10 
  days 
  later. 
  

  

  Banding 
  with 
  tree 
  tanglefoot 
  will 
  check 
  migrations 
  and 
  is 
  recom- 
  

   mended 
  where 
  the 
  hopyards 
  are 
  infested 
  by 
  food 
  plants 
  of 
  the 
  red 
  

   spider. 
  

  

  Two 
  later 
  spray 
  applications 
  may 
  be 
  necessary 
  if 
  the 
  mites 
  again 
  

   appear 
  in 
  injurious 
  numbers. 
  

  

  The 
  red 
  spider 
  on 
  the 
  hopvine 
  may 
  be 
  economically 
  controlled 
  if 
  

   the 
  foregoing 
  measures 
  are 
  carefully 
  carried 
  out. 
  

  

  CONTROL 
  OF 
  THE 
  RED 
  SPIDER 
  UPON 
  PLANTS 
  OTHER 
  THAN 
  

  

  HOPS 
  AND 
  COTTON. 
  

  

  The 
  flour 
  paste, 
  8-100, 
  as 
  described 
  on 
  pages 
  24 
  and 
  27 
  of 
  this 
  

   bulletin, 
  is 
  a 
  successful 
  remedy 
  for 
  the 
  control 
  of 
  the 
  red 
  spider 
  

   in 
  its 
  attacks 
  on 
  all 
  plants 
  except 
  sweet 
  pea, 
  carnation, 
  green- 
  

   house 
  roses, 
  and 
  plants 
  having 
  a 
  heavy 
  pubescence 
  on 
  the 
  leaves. 
  

   Experiments 
  have 
  been 
  conducted 
  with 
  this 
  material 
  against 
  the 
  

   mites 
  upon 
  the 
  following 
  plants 
  without 
  the 
  slightest 
  injury 
  to 
  open- 
  

   ing 
  buds, 
  foliage, 
  or 
  fruit; 
  

  

  