﻿FUNGI 
  AND 
  FUNGOUS 
  DISEASES 
  OF 
  PLANTS 
  253 
  

  

  before 
  the 
  smut 
  appears 
  on 
  the 
  surface, 
  its 
  mycelium 
  grows 
  

   more 
  or 
  less 
  throughout 
  the 
  corn 
  plant. 
  Every 
  part 
  of 
  the 
  

   host 
  may 
  be 
  infested 
  by 
  the 
  mycelium, 
  which 
  grows 
  wholly 
  

   by 
  means 
  of 
  food 
  material 
  derived 
  from 
  the 
  host. 
  In 
  addition 
  

   to 
  this 
  food 
  tax 
  levied 
  upon 
  the 
  host 
  by 
  the 
  parasite, 
  the 
  corn 
  

   grains 
  and 
  tassels 
  are 
  often 
  occupied 
  and 
  eventually 
  destroyed 
  

   by 
  the 
  smut. 
  Finally 
  the 
  spores 
  may 
  fall 
  to 
  the 
  ground 
  and, 
  

   after 
  a 
  period 
  of 
  dormancy, 
  germinate 
  and 
  produce 
  a 
  short 
  

   hypha, 
  which 
  bears 
  spores 
  that 
  may 
  serve 
  to 
  infect 
  the 
  next 
  

   crop 
  of 
  corn 
  with 
  the 
  parasite. 
  1 
  

  

  241. 
  Oat 
  smut. 
  The 
  behavior 
  of 
  this 
  parasitic 
  plant 
  (Usti- 
  

   lago 
  avcnae) 
  (fig. 
  197) 
  is 
  similar 
  to 
  that 
  of 
  corn 
  smut. 
  The 
  

   ripened 
  spores 
  may 
  lie 
  upon 
  the 
  ground, 
  adhere 
  to 
  the 
  grains, 
  

   or 
  remain 
  upon 
  the 
  straw 
  until 
  there 
  are 
  favorable 
  conditions 
  

   for 
  growth. 
  Probably 
  the 
  grain 
  used 
  for 
  seed 
  is 
  one 
  of 
  the 
  

   chief 
  means 
  of 
  spore 
  distribution. 
  It 
  has 
  been 
  found 
  that 
  by 
  

   treating 
  seed 
  oats 
  for 
  a 
  brief 
  period 
  with 
  hot 
  water 
  (132 
  to 
  

   133 
  F.) 
  or 
  with 
  water 
  containing 
  -^ 
  per 
  cent 
  formalin 
  the 
  

   smut 
  may 
  be 
  killed. 
  

  

  It 
  is 
  possible 
  for 
  both 
  corn 
  and 
  oats 
  to 
  mature 
  grain 
  even 
  

   while 
  infected 
  with 
  smut, 
  but 
  usually 
  partial 
  or 
  total 
  destruc- 
  

   tion 
  of 
  the 
  grains 
  results. 
  Some 
  kinds 
  of 
  corn 
  and 
  oats 
  seem 
  

   to 
  be 
  more 
  resistant 
  than 
  others 
  to 
  attacks 
  from 
  the 
  disease. 
  

   The 
  importance 
  of 
  preventing 
  the 
  growth 
  of 
  smut 
  by 
  treatment 
  

   of 
  seed 
  oats 
  and 
  corn 
  and 
  by 
  a 
  search 
  for 
  resistant 
  varieties 
  

   of 
  oats 
  and 
  corn 
  is 
  evident. 
  

  

  242. 
  The 
  rust 
  fungi. 
  The 
  rusts 
  are 
  among 
  the 
  most 
  widely 
  

   distributed 
  and 
  most 
  destructive 
  plant 
  parasites. 
  Many 
  kinds 
  

   of 
  plants 
  are 
  susceptible 
  to 
  attacks 
  from 
  rusts. 
  Indeed, 
  a 
  given 
  

   kind 
  of 
  rust 
  may 
  live 
  for 
  a 
  time 
  upon 
  one 
  kind 
  of 
  host 
  plant 
  

   and 
  later 
  upon 
  another 
  kind. 
  In 
  each 
  stage 
  the 
  rust 
  presents 
  

   a 
  different 
  appearance 
  ; 
  because 
  of 
  this, 
  in 
  earlier 
  studies 
  

  

  1 
  "Corn 
  Smut," 
  Ind. 
  Agr. 
  Exp. 
  Sta., 
  1900. 
  

  

  "The 
  Smut 
  of 
  Grain 
  Crops," 
  Bulletin 
  122, 
  Minn. 
  Agr. 
  Exp. 
  Sta., 
  1911. 
  

   "The 
  Smuts 
  of 
  Wheat, 
  Oats, 
  Barley, 
  and 
  Corn," 
  Farmers' 
  Bulletin 
  507, 
  

   U.S. 
  Dept. 
  Agr., 
  1912. 
  

  

  