﻿I 
  

  

  18 
  CIRCULAR 
  2 
  7 
  0, 
  U. 
  S. 
  DEPARTMENT 
  OF 
  AGRICULTURE 
  

  

  control 
  of 
  the 
  woolly 
  apple 
  aphid 
  Kiver 
  for 
  many 
  years, 
  but 
  was 
  not 
  

   in 
  most 
  orchards. 
  HoweA^er, 
  the 
  found 
  in 
  the 
  Pacific 
  Northwest 
  

   use 
  of 
  DDT 
  for 
  controlling 
  the 
  until 
  1939. 
  It 
  has 
  now 
  spread 
  

   codling 
  moth 
  reduces 
  the 
  Aphe- 
  throughout 
  eastern 
  Washington, 
  

   linus 
  parasites 
  to 
  the 
  point 
  where 
  northern 
  Oregon, 
  and 
  northern 
  

   they 
  become 
  ineffective, 
  and 
  in- 
  Idaho 
  wherever 
  pears 
  are 
  grown, 
  

   secticicles 
  must 
  be 
  resorted 
  to. 
  and 
  in 
  time 
  ma}^ 
  infest 
  the 
  other 
  

   Benzene 
  hexachloride, 
  2 
  pounds 
  of 
  pear-growino- 
  areas 
  of 
  the 
  West, 
  

   material 
  containing 
  10 
  to 
  12 
  per- 
  Injury 
  is 
  limited 
  to 
  pears. 
  Honey- 
  

   cent 
  of 
  a 
  gamma 
  isomer 
  to 
  100 
  dew 
  secreted 
  b}^ 
  the 
  insects 
  runs 
  

   gallons 
  of 
  spray, 
  is 
  very 
  effective 
  down 
  over 
  the 
  foliage 
  and 
  fruit, 
  

   against 
  the 
  woolly 
  apple 
  aphid, 
  and 
  a 
  sooty 
  fungus 
  grows 
  in 
  it 
  

   It 
  should 
  be 
  added 
  to 
  the 
  first 
  (fig. 
  21). 
  The 
  skin 
  of 
  the 
  fruit 
  

   DDT 
  spray 
  applied 
  for 
  control 
  of 
  becomes 
  scarred 
  and 
  blackened 
  

   the 
  codling 
  moth. 
  If 
  used 
  later 
  where 
  the 
  honeydew 
  occurs, 
  and 
  

   than 
  this, 
  benzene 
  hexachloride 
  

  

  may 
  impart 
  an 
  off 
  -flavor 
  and 
  ob- 
  -lA^ife. 
  

  

  jectionable 
  odor 
  to 
  the 
  fruit. 
  If 
  ^1F^^ 
  

   j^arathion 
  or 
  toxaphene 
  is 
  used 
  in 
  

  

  subsequent 
  applications 
  for 
  con- 
  j# 
  

  

  trolling 
  orchard 
  mites, 
  the 
  woolly 
  fc 
  

  

  apple 
  aphid 
  will 
  usually 
  be 
  held 
  in 
  : 
  ^-^V..-. 
  

  

  check 
  sufficiently 
  so 
  that 
  special 
  *"""'"'^"r^ 
  

   applications 
  will 
  be 
  unnecessary. 
  

  

  It 
  is 
  extremely 
  difficult 
  to 
  con- 
  ^ 
  

  

  trol 
  aphids 
  on 
  the 
  roots. 
  The 
  most 
  \ 
  -'I 
  

  

  practical 
  method 
  is 
  to 
  keep 
  the 
  ^'^ 
  

   trees 
  in 
  a 
  thrifty, 
  vigorous 
  condi- 
  

   tion, 
  by 
  means 
  of 
  proper 
  cultiva- 
  

   tion 
  and 
  fertilization, 
  so 
  that 
  they 
  

   can 
  withstand 
  the 
  attacks 
  of 
  these 
  

  

  insects. 
  Applications 
  of 
  tobacco 
  ^-^^^^ 
  21.-Pear 
  damaged 
  by 
  the 
  pear 
  

  

  refuse 
  about 
  the 
  roots, 
  fumigation 
  psylla. 
  

   with 
  carbon 
  disulfide, 
  and 
  other 
  

  

  remedial 
  treatments 
  have 
  been 
  the 
  foliage 
  develops 
  brown 
  spots, 
  

  

  tried, 
  but 
  they 
  are 
  not 
  always 
  sue- 
  Severe 
  infestations 
  ma}- 
  cause 
  par- 
  

  

  cessf 
  ul. 
  Paradichlorobenzene, 
  rec- 
  tial 
  defoliation 
  of 
  the 
  tree, 
  reduc- 
  

  

  ommended 
  for 
  controlling 
  the 
  ing 
  its 
  vitality, 
  and 
  may 
  prevent 
  

  

  peach 
  tree 
  borer, 
  has 
  been 
  used 
  normal 
  formation 
  of 
  buds. 
  The 
  

  

  with 
  some 
  success 
  against 
  the 
  honeydew 
  is 
  also 
  a 
  great 
  incon- 
  

  

  woolly 
  aphid, 
  particularly 
  on 
  old 
  venience 
  to 
  pickers, 
  

   trees. 
  It 
  should 
  be 
  applied 
  in 
  the 
  

   same 
  manner 
  as 
  for 
  the 
  peach 
  

  

  borer 
  (p. 
  38), 
  at 
  any 
  time 
  during 
  The 
  pear 
  psylla 
  (fig. 
  22) 
  winters 
  

  

  the 
  summer 
  or 
  fall, 
  at 
  the 
  rate 
  of 
  as 
  an 
  adult 
  in 
  crevices 
  and 
  in 
  the 
  

  

  % 
  or 
  1 
  ounce 
  per 
  tree. 
  bark 
  or 
  under 
  leaves 
  on 
  the 
  

  

  Pear 
  Psylla 
  -^^^^"'?- 
  ^^'^ 
  ''^^'^^^. 
  ^^^\^^^ 
  ^) 
  

  

  1 
  EAR 
  i 
  bYLLA 
  ^^^^ 
  ^y^^^^^ 
  one-tenth 
  inch 
  long, 
  

  

  The 
  pear 
  psylla 
  was 
  first 
  found 
  dark 
  reddish-brown, 
  with 
  trans- 
  

  

  in 
  the 
  United 
  States 
  in 
  Connecti- 
  parent 
  wings 
  that 
  slope 
  down 
  over 
  

  

  cut 
  in 
  1832, 
  evidently 
  havin,g 
  come 
  the 
  body, 
  giving 
  the 
  insect 
  some- 
  

  

  from 
  Europe. 
  It 
  has 
  been 
  a 
  pest 
  what 
  the 
  appearance 
  of 
  a 
  minia- 
  

  

  of 
  pear 
  east 
  of 
  the 
  Mississippi 
  ture 
  cicada. 
  They 
  may 
  become 
  ac- 
  

  

  