482 
November  30,  1699. 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
The  canker  fungus  attacks  some  varieties  of  Apple  trees  more  than 
others.  Those  which  yield  the  best  eating  Apples  are  most  liable  to 
it.  Cox’s  Orange  Pippin  is  a  variety  subject  to  this  disorder,  as  is 
alsojthe  Ribston  Pippin,  while  the  Golden  Pippin,  and  several  of  the 
Rennets  or  Reinettes,  notably  Reinette  des  Carmes,  are  somewhat 
liable  to  canker.  Trees  with  the  thinnest  and  smoothest  bark  are 
most  liable.  In  France,  trees  bearing  cider  fruit  are  not  usually 
cankered  as  much  as  those  producing  fruit  for  the  table.  Varieties  of 
the  Reinette  type  are  specially  attacked,  as  well  as  some  of  the  Calville 
tribe ;  and  in  Germany,  according  to  Goethe,  Reinettes,  especially  the 
Reinette  de  Canada,  are  most  frequently  infected.  Goethe  states  that 
the  canker  fungus  is  very  common  in  Alsace  and  in  the  Rhine  districts 
of  Prussia,  where  thousands  of  trees  succumb  every  year  to  its  attack, 
lie  adds  that  there  are  certain  regions  where  the  Apple  trees  most 
liable  to  infection  cannot  be  cultivated. 
Pear  trees  are  affected  by  Nectria  ditissima  in  the  same  way  as 
Apple  trees.  Fortunately  in  this  country  the  attack  on  Pear  trees  is 
not  so  frequent  as  on  Apple  trees,  though  in  France  it  appears  to 
affect  both  pretty  equally.  The  effect  of  the  fungus  and  its  methods 
of  attack  are  precisely  the  same  as  upon  Apple  trees.  Plum  trees  are 
also  infected  by  this  fungus. 
This  fungus  is  also  destructive  to  Oak,  Beech,  Ash,  Hazel,  Alder, 
Maple,  and  Lime  trees. 
Description  and  Life  History. 
The  perithecia,  or  spore-bearing  cases,  of  the  fungus  appear  first  as 
minute  red  dots.  From  the  spores  emanating  from  these  a  mycelium 
is  produced  which  penetrates  the  rind  and  wood,  whose  juicy  tissues 
are  dried  up  and  destroyed.  The  action  of  the  mycelium  in  course  of 
time,  though  it  moves  slowly,  causes  distortions  and  malformations  of 
the  surrounding  parts,  and  death  to  all  the  branch  above  the  centre 
of  its  action.  Perithecia,  or  spore-bearing  cases,  are  formed  on  the  sur¬ 
face  of  the  rind  after  a  time.  They  are  crimson,  and  are  found  in  small 
groups ;  they  are  clearly  visible  to  the  naked  eye,  and  are  slightly  flask¬ 
shaped.  Within  these  are  cylindrically  formed  asci  containing  eight 
spores,  each  having  two  colourless  cells.  They  germinate  in  water 
quickly,  and  placed  upon  trees  infect  them  with  canker.  Hartig  and 
Goethe  have  infected  forest  trees  by  placing  spores  of  Nectria  ditissima 
upon  their  living  parts.  They  have  also  infected  trees  by  placing  Nectria 
spores  upon  parts  injured  by  hail,  or  with  decayed  matter  on  them, 
and  show  that  Nectria  ditissima  is  both  saprophytic  and  parasitic. 
This  has  also  been  proved  by  De  Bary. 
In  addition  to  the  perithecia  emanating  from  the  mycelium  of 
Nectria  ditissima  there  is,  at  all  events  when  it  is  actively  parasitic,  a 
formation  of  conidia  evolved  from  a  stroma  of  cushion  shape.  This 
takes  place  before  the  development  of  the  perithecia,  which  contain 
the  spore-bearing  asci.  These  conidia  have  also  been  made  by  Hartig 
and  Goethe  to  infect  forest  trees,  and  to  germinate  freely  upon  decayed 
and  living  tissues. 
Methods  of  Prevention  and  Remedies. 
One  obvious  way  of  preventing  the  spread  of  canker  is  to  be  careful 
not  to  make  use  of  grafts  from  infected  trees,  or  grafts  showing  any 
trace  of  the  fungus. 
Young  trees  should  be  examined  closely  for  any  signs  of  canker. 
Any  wounds  caused  by  hail,  pruning,  or  other  causes,  upon  them 
should  be  viewed  with  a  strong  pocket  glass  to  discover  the  red 
perithecia  of  the  fungus. 
Infected  parts  should  be  cut  out  with  a  sharp  knife,  and  tar 
applied,  and,  where  possible,  infected  branches  should  be  cut  away, 
and,  together  with  all  the  pieces  cut  out,  burnt  to  prevent  the  spread 
of  the  lungus. 
It  would  be  desirable  to  note  the  trees  that  canker  most  readily, 
and  to  avoid  planting  these  varieties.  And  if  a  tree  is  badly  cankered 
iu  an  orchard,  or  near  other  trees,  it  would  be  expedient  to  cut  it 
down  and  burn  it. 
A  strong  solution  made  with  20  lbs.  of  sulphate  of  copper  to 
100  gallons  of  water  applied  in  the  late  autumn  or  winter,  would 
undoubtedly  check  the  fungus  and  destroy  it  in  its  conidia  and  spore 
stages.  This  could  be  applied  with  a  knapsack  machine  where  the 
trees  are  small,  and  upon  large  trees  with  the  help  of  a  ladder  where 
the  disease  has  affected  only  a  few  branches.  The  spray  should  be 
directed  for  some  time  on  the  infected  spots,  and  it  would  be  necessary 
to  spray  them  two  or  three  times  during  the  winter. 
When  trees  are  badly  infected  they  must  be  sprayed  all  over  by 
means  of  a  garden  engine  with  strong  pumps  and  long  hose,  like  the 
engine  used  for  hop  washing. 
Sulphate  of  iron,  dissolved  in  warm  water,  would  be  of  value  if 
applied  in  the  autumn  and  winter  at  the  rate  of  1  lb.  to  every  gallon 
ot  water.  It  would  at  the  same  time  remove  lichenous  and  mossy 
growths  which  harbour  fungi  and  insects,  and  injuriously  affect  the 
trees. 
Apple  trees  should  be  kept  free  from  the  common  Apple  aphis,  and 
tire  woolly  aphis,  as  these  convey  fungus  spores  from  tree  to  tree.  In 
woods  and  plantations  the  diseased  branches  should  be  removed  from 
infected  trees  and  burnt.  Foresters  should  examine  trees  that  show 
signs  of  decay  with  a  pocket  lens  to  ascertain  if  the  Nectria  ditissima  is 
the  cause  of  the  evil. 
[We  reprint  this  Board  of  Agriculture  leaflet  because  there  is  much 
that  is  good  and  suggestive  in  it.  We  are,  however,  rather  sorry  to 
see  in  paragraph  2  the  writer  distinctly  implies  that  nothing  can  be 
done  by  intelligent  cultivation  to  fortify  trees  against  the  inroads  of 
the  fungus.  According  to  the  dicta  of  the  writer  ot  the  leaflet,  no 
matter  how  wet  and  cold  the  site,  or  unsuitable  the  soil  by  excess  or 
lack  of  manuring  constituents,  we  have  only  to  spray  the  trees  with 
sulphate  of  copper  in  autumn  or  winter  to  insure  them  against 
cankerous  infestation.  We  have  nothing  to  say  against  spraying;  it 
is  a  good  and  commendable  practice ;  but  we  suspect  thousands  of 
cases  of  canker  have  been  cured  without  it,  and  thousands  more 
prevented  by  sound  and  intelligent  cultural  methods.  What  do 
practical  gardeners  say  ?  The  leaflet  can  be  had  on  application  from 
4,  Whitehall  Place,  S.W.] 
IRIS  KiEMPFERI. 
Any  experience  which  will  lead  to  the  introduction  of  the  noble 
Iris  Ksempferi  into  gardens  from  which  it  is  still  absent,  is  of  much 
value.  Thus  one  has  lead  with  pleasure  the  clear  and  useful  notes 
by  Mr.  Upex  in  the  Journal  of  Horticulture,  page  447.  Like  many 
other  plants  Iris  Ksempferi  has  different  requirements  in  different 
gardens.  One  knows  of  some  in  which  it  grows  and  flowers  regu¬ 
larly  in  the  border  without  any  special  treatment.  In  others,  again, 
it  requires  a  hollow  round  it,  if  in  a  mixed  border,  for  the  purpose  ot 
giving  it  a  larger  supply  of  water.  In  some  garden  this  is  effected  by 
sinking  a  flower  pot  into  the  ground  close  beside  the  Iris ;  into  this 
the  water  is  poured.  Where  a  bed  can  be  set  apart,  as  Mr.  Upex  has 
done,  these  requirements  in  the  way  of  liquid  nourishment  ean  be 
readily  supplied,  and  your  correspondent’s  method  may  be  commended 
to  those  who  can  follow  it.  I  think  that  Mr.  Upex  will  probably  in 
a  short  time  reap  the  reward  of  his  carefully  planned  endeavour. 
I  desire,  however,  now  that  the  subject  has  been  so  ably  ventilated, 
to  urge  upon  Ihose  who  have  the  opportunity  the  wisdom  of  making 
a  liberal  use  of  this  truly  magnificent  Iris  as  an  aquatic  or  semi- 
aquatic  plant.  From  time  to  time  I  have  come  across  it  under  these 
conditions,  and  growing  and  flowering  with  a  freedom  unattainable 
under  other  treatment.  In  shallow  ditches,  by  the  margins  of  ponds, 
or  in  the  shallow  water  at  the  edges  of  the  latter,  it  will  thrive  and 
give  its  noble  blossoms  with  freedom.  For  all  such  (and,  indeed,  all 
other)  positions  it  ought  to  be  planted  in  full  sun.  With  its  roots  in 
water  and  its  leaves  nearly  all  in  full  sun,  it  is  charmingly  successful. 
I  do  not  think,  however,  that  it  will  do  so  well  in  cold,  running 
water. 
Iris  Susiana. 
I  do  not  think  that  Mr.  Upex  is  likely  to  have  as  much  satisfac¬ 
tion  with  Iris  Susiana  as  with  Iris  Ksempferi  in  the  same  border.  The 
cultivation  required  by  Iris  Susiana  in  most  gardens  is  the  opposite  to 
that  of  I.  Ksempferi.  From  its  flowering  period  it  should  be  kept  as 
dry  as  possible,  and  this  dryness  ought  to  be  as  complete  in  the  soil  as 
in  the  atmosphere.  None  of  us  have  been  able  to  improve  upon  the 
method  of  the  Rev.  Mr.  Ewbank,  who,  even  in  the  Isle  of  Wight,  finds 
it  needful  in  growing  this  and  allied  Irises  to  keep  the  natural  moisture 
of  the  soil  from  ascending  by  interposing,  between  the  layer  on  which 
the  Irises  grow  and  that  beneath,  a  stratum  of  flat  paving  stones. 
I  had,  however,  the  opportunity  of  seeing  this  year  a  fine  little  clump 
at  the  base  of  a  south  wall  and  in  a  very  dry  soil,  where  the  latter 
precaution  to  obstruct  the  rising  mo:sture  was  not  adopted,  and  where 
the  clump  flowered  regularly.  One  will,  notwithstanding,  look 
forward  with  more  than  ordinary  interest  to  the  results  of  the  efforts 
of  your  able  contributor,  whose  practical  articles  deserve  our  best 
thanks. — S.  Arnott. 
I  am  grateful  to  Mr.  J.  S.  Upex,  page  447,  for  giving  us  an  account 
of  his  experience  with  this  Iris,  and  also  for  detailing  his  plans  for  the 
future.  For  a  long  time  I  have  felt  tempted  to  ask  if  someone 
among  the  numerous  readers  of  the  Journal  would  enlighten  us  in  the 
mystery  (if  mystery  there  be)  attending  the  culture  of  this  beautiful 
plant.  I  find  imported  pieces  fairly  easy  to  flower  for  the  first  time, 
but  I  have  never  yet  succeeded  in  flowering  the  stock  the  second  time, 
the  growth  getting  weaker  every  year.  With  me  a  sort  of  a  dry  rot 
seems  to  attack  them  in  the  growing  season,  and  almost  the  first  sign 
of  anything  wrong  has  been  the  sudden  collapse  of  the  current 
growth,  and  upon  examination  the  rhizomes  are  found  to  be  completely 
ruined. 
I  have  also  tried  I.  Lorteti  and  I.  Gatesi,  which  I  believe  to  belong 
to  the  family  of  Cushion  Iris,  but  have  never  yet  succeeded  in 
flowering  a  piece.  I  have  grown  all  three  varieties  in  pots,  also  in 
a  specially  prepared  frame,  much  the  same  as  mentioned  by  your 
