-514  Annual  Report  for  1910  of  the  Botanist. 
remain  over  the  winter  ready  to  form  a fresh  centre  of 
infection  in  the  following  spring. 
Sainfoin. — One  Member,  while  sending  specimens  of  this 
plant,  reported  a gradual  failure  of  the  crop.  On  examination 
black  resting  bodies  (sclerotia)  of  one  of  the  Sclerotinias  were 
found  just  below  the  crown  of  the  plant.  They  probably 
belonged  to  a fungus  very  similar,  if  not  identical,  with  that 
responsible  for  clover-sickness.  There  should  be  no  difficulty 
in  dealing  with  this  parasite  if  the  starving-out  method  used 
for  the  latter  disease  is  adopted,  for  it  is  unlikely  that  the 
resting  bodies  can  remain  in  a living  condition  in  the  soil  for 
more  than  four  years. 
Swedes. — Two  lots  of  swedes  attacked  by  a bacterium 
Pseudomonas  destructans  were  received  from  Members  of  the 
Society  in  the  south  and  south-west  of  the  country.  The 
disease,  though  common  in  the  north  of  England,  does  not 
appear  to  be  at  all  abundant  in  other  parts.  The  infected  roots 
become  hollow,  the  process  generally  starting  at  the  crown. 
In  the  early  stages  of  decay  the  rotten  portions  teem  with 
bacteria.  Though  attacked  in  this  fashion  the  roots  often 
continue  to  grow,  becoming  ultimately  cup-like  shells,  contain- 
ing a foul-smelling  pulp,  with  their  edges  covered  with  small 
foliage  leaves.  Where  the  disease  occurs  the  further  cultivation 
of  swedes  in  the  same  fields  should  be  postponed  as  long  as 
possible.  A dressing  of  lime,  after  the  removal  of  the  crop, 
would  probably  prove  beneficial. 
Potatoes. — One  case  of  “ corky-scab  ” of  potatoes  was  met 
with  in  Cambridgeshire.  The  disease  is  said  to  be  rampant  in 
the  west  of  Ireland,  and  in  view  of  the  extended  use  of  Irish  seed 
potatoes,  some  account  of  it  is  given  below.  Fuller  particulars 
may  be  found  in  the  Journal  of  the  Board  of  Agriculture , 
Vol.  XV.,  page  592.  The  tubers  when  first  attacked  show 
small,  slightly-raised  and  dark-coloured  patches  which  are 
often  crowded  together  in  clusters  instead  of  being  more  or  less 
uniformly  distributed  over  the  surface  as  is  the  case  with  other 
scab  diseases.  As  the  attack  progresses  the  patches  become 
roughened  and  masses  of  brown-coloured  spores  are  extruded 
from  them.  The  diseased  areas  are  often  completely  isolated 
from  the  sounder  parts  of  the  tuber  by  the  formation  of  cork 
layers.  Consequently  the  potatoes  do  not  as  a rule  show  any 
further  signs  of  decay,  and  though  their  rough  scabby  exterior 
may  make  them  unsaleable  for  food,  they  can  still  be  used  for 
seed  purposes.  Such  tubers  should  on  no  account,  however,  be 
used  for  seed,  for  the  planter  runs  not  only  the  risk  of  raising  a 
“ scabby”  crop  from  them,  but  the  further  risk  of  having  to 
keep  his  fields  free  from  potatoes  until  the  fungus  can  be  starved 
out  of  them. 
