﻿PLANT 
  INDUSTRIES 
  331 
  

  

  In 
  some 
  cases 
  where 
  solutions 
  have 
  not 
  been 
  forthcoming, 
  

   attention 
  is 
  being 
  centered 
  upon 
  securing 
  resistant 
  varieties 
  

   of 
  plants 
  rather 
  than 
  upon 
  preventing 
  the 
  disease. 
  In 
  open 
  

   nature 
  many 
  plants 
  thrive 
  and 
  are 
  not 
  affected 
  by 
  diseases 
  

   which 
  affect 
  other 
  plants 
  of 
  the 
  same 
  kind 
  ; 
  that 
  is, 
  some 
  

   plants 
  are 
  resistant 
  and 
  some 
  are 
  susceptible. 
  Other 
  plants 
  

   may 
  have 
  certain 
  diseases 
  but 
  are 
  not 
  killed 
  by 
  them, 
  as 
  in 
  

   the 
  case 
  of 
  the 
  lilac 
  and 
  the 
  disease 
  known 
  as 
  lilac 
  mildew. 
  A 
  

   good 
  illustration 
  of 
  the 
  value 
  of 
  the 
  study 
  of 
  disease 
  resistance 
  

   is 
  presented 
  in 
  connection 
  with 
  grape 
  plants 
  and 
  an 
  insect 
  

   (phylloxera) 
  which 
  is 
  parasitic 
  upon 
  the 
  roots 
  of 
  the 
  grape. 
  

   The 
  grapes 
  cultivated 
  in 
  Europe 
  are 
  descended 
  from 
  a 
  

   European 
  wild 
  species 
  ; 
  the 
  principal 
  varieties 
  cultivated 
  in 
  

   the 
  middle 
  and 
  eastern 
  United 
  States 
  are 
  descended 
  from 
  

   American 
  wild 
  species. 
  Since 
  the 
  French 
  grapes 
  produced 
  a 
  

   quality 
  of 
  wine 
  that 
  differed 
  from 
  that 
  made 
  from 
  the 
  grapes 
  

   of 
  the 
  United 
  States, 
  European 
  grapes 
  were 
  brought 
  to 
  this 
  

   country. 
  Their 
  roots 
  were 
  soon 
  attacked 
  and 
  the 
  plants 
  well- 
  

   nigh 
  destroyed 
  by 
  the 
  phylloxera. 
  It 
  was 
  found, 
  however, 
  

   that 
  the 
  roots 
  of 
  the 
  American 
  grapes 
  were 
  able 
  to 
  withstand 
  

   attacks 
  from 
  phylloxera 
  and 
  were 
  not 
  seriously 
  affected 
  by 
  it. 
  

   It 
  was 
  also 
  found 
  that 
  when 
  European 
  grapes 
  were 
  brought 
  

   to 
  this 
  country 
  and 
  grafted 
  upon 
  American 
  stock, 
  the 
  quality 
  

   of 
  the 
  European 
  fruit 
  might 
  be 
  secured 
  without 
  the 
  accom- 
  

   panying 
  dangers 
  from 
  the 
  insect. 
  But 
  when 
  grape 
  growers 
  

   transplanted 
  American 
  grapes 
  into 
  Europe, 
  the 
  phylloxera 
  

   was 
  also 
  transferred, 
  and 
  soon 
  the 
  native 
  grapes 
  of 
  Europe 
  

   were 
  attacked 
  and 
  serious 
  damage 
  was 
  done 
  in 
  the 
  vineyards 
  

   of 
  France. 
  It 
  was 
  found 
  that 
  by 
  treating 
  the 
  soil 
  with 
  carbon 
  

   disulphide 
  the 
  phylloxera 
  were 
  killed, 
  but 
  this 
  method 
  usually 
  

   proved 
  too 
  expensive 
  for 
  growers 
  of 
  grapes. 
  Many 
  French 
  

   grape 
  growers 
  adopted 
  the 
  practice 
  of 
  planting 
  American 
  

   plants 
  and 
  then 
  grafting 
  their 
  own 
  grapes 
  upon 
  this 
  intro- 
  

   duced 
  stock. 
  The 
  grape 
  industry 
  of 
  France 
  has 
  been 
  greatly 
  

   increased 
  by 
  thus 
  growing 
  French 
  varieties 
  upon 
  the 
  stronger 
  

   and 
  more 
  resistant 
  American 
  stock. 
  

  

  