﻿422 
  JOURNAL 
  OF 
  THE 
  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  VOL. 
  12, 
  NO. 
  18 
  

  

  Symposium 
  on 
  plant 
  breeding 
  for 
  disease 
  resistance. 
  

  

  W. 
  J. 
  HuMPHREv, 
  Cereal 
  crops. 
  — 
  In 
  the 
  cereal 
  crops 
  some 
  diseases 
  were 
  

   transmitted 
  with 
  the 
  seed 
  as 
  in 
  the 
  case 
  of 
  the 
  smuts. 
  Some 
  measure 
  of 
  suc- 
  

   cess 
  had 
  been 
  achieved 
  with 
  seed 
  treatment, 
  both 
  with 
  the 
  use 
  of 
  chemicals 
  

   and 
  the 
  hot 
  water 
  treatment. 
  It 
  is 
  not 
  enough 
  to 
  develop 
  a 
  disease-resis- 
  

   tant 
  grain, 
  for 
  some 
  of 
  the 
  grains 
  developed 
  by 
  cross 
  breeding, 
  while 
  highly- 
  

   resistant 
  to 
  certain 
  diseases, 
  lacked 
  in 
  milling 
  qualities 
  or 
  in 
  yield. 
  The 
  aim 
  

   of 
  the 
  plant 
  pathologist 
  and 
  the 
  plant 
  breeder 
  was 
  to 
  secure 
  not 
  only 
  disease- 
  

   resistant 
  varieties 
  of 
  grain, 
  but 
  to 
  secure 
  grain 
  of 
  good 
  yield 
  and 
  quality. 
  

  

  W. 
  W. 
  Gilbert, 
  Cotton, 
  truck 
  and 
  forage 
  plants. 
  — 
  A 
  double 
  gain 
  was 
  ob- 
  

   tained 
  by 
  securing 
  disease 
  resistant 
  plants; 
  a 
  gain 
  in 
  the 
  product 
  itself 
  and 
  

   a 
  gain 
  in 
  the 
  greater 
  utilization 
  of 
  the 
  land. 
  There 
  are 
  certain 
  requisites 
  for 
  

   selection 
  and 
  hybridization, 
  to 
  get 
  disease 
  resistant 
  varieties 
  or 
  species. 
  1. 
  

   The 
  land 
  must 
  be 
  naturally 
  or 
  artificially 
  infected. 
  2. 
  Work 
  must 
  be 
  carried 
  

   on 
  in 
  an 
  environment 
  suitable 
  for 
  the 
  disease. 
  3. 
  The 
  use 
  of 
  a 
  large 
  number 
  

   of 
  varieties 
  or 
  strains. 
  

  

  The 
  question 
  arises. 
  Is 
  disease 
  resistance 
  in 
  plants 
  permanent? 
  The 
  

   failure 
  of 
  the 
  cotton 
  farmer 
  to 
  continue 
  selection 
  in 
  the 
  case 
  of 
  wilt-resistant 
  

   cotton, 
  shows 
  how 
  this 
  resistance 
  to 
  disease 
  becomes 
  lessened. 
  Resistance 
  

   to 
  disease 
  is 
  specific. 
  One 
  variety 
  or 
  one 
  plant 
  may 
  be 
  resistant 
  to 
  one 
  dis- 
  

   ease, 
  but 
  that 
  does 
  not 
  signify 
  a 
  resistance 
  to 
  all 
  other 
  diseases. 
  

  

  MerTon 
  B. 
  Waite, 
  Fruits. 
  — 
  Much 
  of 
  the 
  early 
  work 
  in 
  breeding 
  for 
  dis- 
  

   ease 
  resistance 
  in 
  plants 
  was 
  carried 
  on 
  by 
  natural 
  selection, 
  the 
  survival 
  of 
  

   the 
  fittest, 
  as 
  well 
  as 
  consciously 
  by 
  orchardists. 
  The 
  gardener 
  and 
  orchard- 
  

   ist 
  have 
  done 
  as 
  much 
  as 
  the 
  plant 
  breeder 
  or 
  plant 
  pathologist 
  along 
  this 
  

   line. 
  A 
  number 
  of 
  projects 
  were 
  being 
  worked 
  in 
  the 
  Bureau 
  of 
  Plant 
  Indus- 
  

   try, 
  including 
  Dr. 
  Swingle's 
  work 
  of 
  breeding 
  for 
  resistance 
  to 
  citrus 
  canker. 
  

   The 
  breeding 
  of 
  resistant 
  stocks 
  was 
  emphasized 
  as 
  being 
  important. 
  

  

  P. 
  L. 
  RiCKER, 
  Grasses.— 
  'New 
  grasses 
  are 
  being 
  introduced 
  into 
  this 
  country 
  

   from 
  various 
  foreign 
  countries. 
  Some 
  of 
  these 
  are 
  found 
  to 
  be 
  subject 
  to 
  

   variou 
  diseases 
  in 
  their 
  native 
  country, 
  as 
  well 
  as 
  in 
  this 
  country. 
  One 
  of 
  the 
  

   biggest 
  problems 
  is 
  in 
  connection 
  with 
  lawn 
  grasses 
  on 
  golf 
  links, 
  which 
  

   suffered 
  from 
  so-called 
  sun 
  scald, 
  which 
  was 
  found 
  to 
  be 
  a 
  Rhizoctonia. 
  

   Strains 
  of 
  grasses 
  which 
  were 
  resistant 
  to 
  this 
  disease 
  in 
  one 
  year, 
  were 
  propa- 
  

   gated 
  vegetatively 
  and 
  were 
  fairly 
  immune 
  for 
  a 
  couple 
  of 
  years, 
  but 
  in 
  the 
  

   third 
  year 
  were 
  wiped 
  out 
  completely. 
  

  

  Roy 
  G. 
  Pierce, 
  Recording 
  Secretary. 
  

  

  