3«9 
of  rul)ber  from  the  latex  and  the  difficulties  that  are  encountered 
therein. 
f To  be  continued .) 
THE  CANKER  FUNGUS  IN  RUBBER. 
A lecture  by  Mr.  J.  B.  Carruthers,  Government  Mycologist,  to 
the  Kalutara  Planters  Association,  Tebuwana,  Ceylon. 
Mr.  Carruthers'  Address. 
Mr.  J.  B.  Carruthers,  who,  on  rising  was  received  with  ap- 
plause, said;  Gentlemen,  to  begin  with  the  history  of  the  disease, 
I may  mention  that  it  was  first  noticed  two  years  ago  by  the  Assis- 
tant Conservator  of  Forests  of  the  Province  of  Sabaragamuwa ; but 
it  was  not  till  some  five  months  ago  that  my  attention  was  called 
to  it.  Following  this  various  diseased  speciments  of  rubber  were 
sent  to  me  from  a number  of  districts,  and,  in  some  of  these  speci- 
mens, I found  the  nectria  or  canker  fungus.  The  specimens  sent 
contained  mycelium,  and,  on  investigating  this  by  means  of  cultures, 
I found  spores,  which,  on  scrutiny,  showed  that  they  belonged  to  a 
species  of  nectria.  I then  made  inoculations  on  trees,  and  that  is 
the  only  way  to  prove  the  guilt  of  an  individual  parasitic  fungus  as 
the  cause  of  any  disease.  Nectria  grow  on  apple  trees,  plum, 
cacao,  tea,  etc.,  etc.,  and  affect  and  eventually  fill  many  kinds  of 
trees. 
After  these  preliminary  investigations  had  been  to  some  extent 
finished  in  the  laboratory  at  Peradeniya,  I visited  Kalutara  and 
went  over  some  fifteen  or  more  estates,  and  have  seen  practically 
all  the  rubber  estates  of  any  size.  The  result  of  this  inspection  is 
that  the  estimated  proportion  of  diseased  trees  in  the  Kalutara  dis- 
trict is  about  one  in  two-hundred  or  h per  cent.  Yatiporua  and 
Edengoda  estates  on  the  other  side  of  the  river  are  not  included  in 
this  record.  If  they  are  included  it  would  about  double  the  per- 
centage* and  make  it  over  i per  cent.  Yatiporua  has  about  40  per 
cent,  trees  affected  by  canker  and  Edengoda  20  per  cent.  The 
canker  has  been  there  for  some  years,  possibly  five  or  even  more. 
Details  of  the  effects  and  structure  of  the  fungus  will  be  given  in  a 
circular  of  the  Royal  Botanic  Gardens,  so  that  there  is  no  need  for 
me  to  take  up  your  time  with  these.  Coming  now  to  observe  the 
aspect  of  the  disease  on  trees,  as  a general  rule  the  external  ap- 
pearances on  the  rubber  tree  are  roughened  and  swollen  places  in 
the  stem  and  branches.  These,  on  cutting  off  the  outer  bark,  show 
discoloured  tissue,  at  first  a neutral  tint  colour,  and  afterwards 
brownish  and  claret  colour.  When  shaved  the  whole  of  the  diseased 
parts  are  shown  up  like  an  outlined  coloured  map  in  the  lighter- 
coloured  healthy  tissue.  When  the  canker  fungus  has  been  grow- 
ing in  such  a spot  for  some  time — I cannot  definitely  say  how  long, 
as  this  depends  on  physiological  conditions — the  fruits  are  produced, 
at  first  pink  or  whitish  spores,  and  later  round  red  fruits  like 
