Diseases  of  Plants. 
261 
The  ureclospores  are  followed  by  teleutospores  (rest  spores), 
which  have  thick  -walls,  an  efficient  protection  to  carry  them 
through  the  winter.  This  disease  should  be  treated  like  the 
Pseudopeziza  attack. 
From  Yorkshire  samples  of  diseased  tall  oat  grass  were 
received.  The  fungus  which  had  destroyed  the  grains  in 
the  husk  was  Ustilago  perennans  Rostr.,  a species  of  the 
well-known  smut  fungus.  The  applicant  was  advised  to  collect 
and  burn  the  diseased  plants  ; letting  them  continue  to  grow 
would  endanger  the  cultivation  of  cereals  and  pasture  grasses 
in  the  following  year. 
Mangel  wurzel  and  turnips. — Leaves  of  mangel  wurzel 
covered  with  large  brown  spots  of  dead  tissue  were  examined. 
These  were  killed  by  Gercospora  heticola  Sacc.  (see  Fig.  1,  A 
and  B,  page  262).  At  the  beginning  the  spots  are  very  small, 
but  they  increase  in  size  as  quickly  as  the  mycelium  of  the 
fungus  spreads  in  the  tissues.  Wind  and  rain  toss  the  leaves 
about,  and  consequently  the  dead  portions  become  detached, 
fall  out,  and  leave  holes  of  various  size  in  the  leaf.  Besides 
this  fungus  another  inhabited  the  leaves,  and  was  identified 
as  Uromyces  Betce  Ktihn.,  (see  Fig.  1,  A,  C to  E,  page  262).  This 
is  another  species  of  the  group  which  was  found  on  the 
suckling  clover.  The  nature  of  an  attack  and  the  history  of 
the  fungus  are  closely  related  to  that  species  and  need  no 
repetition.  It  was  advised  to  collect  all  diseased  leaves  and 
burn  them,  as  soon  as  spots  of  this  kind  are  observed.  If  the 
fungus  were  allowed  to  remain,  it  would  kill  the  leaves  and 
little  or  no  nourishment  could  be  stored  in  the  roots,  causing 
serious  loss  in  the  ripening  and  weight  of  the  mangels.  Some 
turnips  affected  by  “ finger-and-toe  ” were  received.  This  is 
caiased  by  a parasitic  fungus,  Plasmodiophora  Brassicce  Wor.’ 
The  remedy  lies  in  the  application  of  lime.  A bacterial  attack 
on  turnips  received  from  Lincolnshire  was  investigated,  and 
found  to  be  identical  with  the  disease  described  in  an  appendix 
to  my  Report  for  1900.“ 
Potatoes. — In  March  I received  some  potatoes  from  Lincoln- 
shire, covered  with  numerous  bluish-black  warts  of  about  a 
quarter  of  an  inch  in  diameter  (Fig.  2,  page  264).  When 
thinly  peeled  a dark-brown  patch  was  found  below  each  wart, 
and  if  crowded  together  the  patches  became  confluent.  On 
dissecting  these  patches  the  cells  of  the  potato  were  found  to 
be  permeated  by  threads  of  very  tine  mycelium.  The  fungus 
had  consumed  the  cell  contents  and  thickened  the  cell  walls, 
forming  a corky  layer  which  separated  the  diseased  part  from 
the  healthy  cells.  No  fructification  or  other  characters  helping 
‘ Journal  R.A.S.E.,  Vol.  64,  1893,  pp.  334-339. 
’ Ibid.,  Vol.  61,  1900,  pp.  738-741. 
