September  23,  1897.  JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER. 
293 
Fig.  43. — Early  Fructifying  Form 
OF  Canker  Fungus  on  Apple 
Tree  Twig. 
References  :—M,  spur  (enlarged  4  dia¬ 
meters);  m,  mussel  scale;  w,  swelling 
(due  to  fungal  hyplite) ;  o,  crack  in  bark ; 
p,  pale  pink  speck.  N,  speck  (natural 
size).  0,  the  same  enlarged  4  diameters. 
P,  ditto,  20  times.  Q,  ditto,  67  dia¬ 
meters.  R.  full-blown  fungus  (enlarged 
20  diameters).  S,  portion  of  fructifica¬ 
tion  (enlarged  267  times’) ;  q.  conidia 
or  spores  =  Tubercularia  e.xpallans. 
woody  ones  beneath.  This  gives  rise  to  the  swelling  on  the  part  of  the 
plant — an  abnormal  growth  of  cellular  and  even  woody  matter,  the 
fungal  hyphfe  always  showing  its  appreciation  by  remaining  in  the  inner 
bark  or  cambial  cells  between 
the  bark  and  wood.  Thus  it 
exploits  the  host.  The  head 
of  the  fungoid  body,  ex¬ 
amined  with  a  lens  enlarging 
400  diameters,  will  be  found 
to  consist  of  delicate  parallel 
threads  compacted  together  to 
form  the  stem  and  head,  some 
of  which  are  simple,  others 
branched  (.S'),  bearing  upon 
them  delicate  little  bodies  — 
conidia  (</),  and  is  the  fungus 
complete  —  capable  of  repi'o- 
duction  or  continuation  by 
seed  (spores).  The  conidia 
are  whitish  and  diaphanous, 
which  on  the  pale  ]unk  stratum 
have  a  beautiful  luminous 
appearance,  and  easily  seen 
with  the  unaided  eye.  The 
whole  is  the  fungus  plant 
named  Tubercularia  expallens, 
Fries. 
When  the  conidia  are  dis¬ 
persed  by  wind,  they,  or  some 
of  them,  may  fall  on  Apple 
or  other  trees  affording  the 
essential  food  of  the  Tuber¬ 
cularia,  and,  lodging  in  a 
crack  or  hole  made  by  the 
beak  of  a  female  mussel  scale, 
push  a  germ-tube  into  the 
crevices  of  the  bark,  and  thus  enter  by  sheer  force  of  growth  into  the 
tissues  of  the  inner  bark.  But  frost  and  many  other  things  may  occur  to 
upset  fungal  schemes,  therefore  this  one  has  jirepared  for  casualties  by 
providing  subglobose  bodies  springing  from  a  common  stroma  or  stem, 
and  following  on  after  the  conidia  are  shed.  These  subglobose  bodies 
are  perithecia,  in  which  the  final  or  comjdete  stage  of  the  fungus  is 
perfected,  so  that  the  seed  (spoi'es)  jiroduced  are  practically  frost,  wet, 
and  drought-proof  while  they  remain  in  the  peril hecium, -and  only  when 
the  weather  is  warm  and  the  air  suffused  by  “  a  soft  glow  of  moisture  ” 
do  they  come  forth,  rising  and  railing  in  the  air  by  means  provided 
for  that  purpose. 
Now  we  come  to  examining  “  F.  W.  C.’s  ”  Apple  tree  branch 
(T,  fig.  44).  It  had  been  sawn  off  at  bottom  (/•),  and  broken  off  at  the 
top  (s),  and  mainly  consisted  of  a  scar.  The  bark  was  off  the  lower  part 
(t),  but  on  the  upper  portion  (m),  was  not  dead,  yet  dried,  evidently 
wanting  sap.  The  part  above  the  scar  must  have  received  nourishment 
in  the  last  two  years  through  the  inner  wood,  or  have  lived  upon  the 
stored  matter  above  for  that  period. 
The  scar  represents  what  had  occurred  during  the  previous  eight 
years,  six  on  the  wood  (1-6),  and  two  on  the  bark  (7  and  8),  each  repre¬ 
senting  the  advance  of  something  at  the  expense  of  the  living  branch. 
The  something  had  entered  at  v,  and  had  come  out  after  eight  seasons, 
as  indicated  hy  the  small  circles  on  the  bark — some  on  the  two-year-old 
(tc),  and  others  on  the,  at  least,  nine  years  old  (x').  even  on  the  inside  edge 
of  a  splintered  part  (y),  and  on  the  older  bark  adhering  in  a  patch  («)  to 
the  scar. 
These  little  bright  pink  pimples  are  round,  and  they  break  through 
the  bark  emmpantly,  being  clustered  together  as  shown  at  U,  enlarged 
four  diameters.  They  become  redder  with  age— a  glowing  crimson,  each  a 
perithecium  (a  receptacle  formed  of  one  valve).  All  are  alike,  but  vary¬ 
ing  considerably  in  size,  and  when  mature  become  brown  or  blackish, 
somewhat  warted  or  pimpled  and  hard.  They  are  attached  to  a  common 
stroma,  and  the  mycelia  spreads  inwards  between  the  hark  and  wood,  but 
growth  is  outwards  in  this  instance,  the  hyphae  compacted  around  the 
pyrithecium  to  form  the  shell,  granular,  and  inside  that  a  sort  of  membrane, 
but  all  cells,  as  also  is  the  internal  contents. 
A  perithecium  is  shown  at  F,  enlarged  67  diameters,  with  a  sort  of 
nipple  at  the  apex  (a),  which  becomes  more  or  less  depressed,  and  ulti¬ 
mately  serves  as  the  aperture  by  which  the  spores  escape  into  the  aii*.  If 
cut  through  when  immature  it  appears  as  figured  at  IF,  externally 
granular  (6),  and  internally  filled  with  a  gelatinous  nucleus  (c).  Later 
on  the  nucleus  develops  fructification  (.Y),  cylindrical  asci  (d),  each 
enclosing  eight  elliptical  sporidia  (spores)  closely  ])acked  together,  and 
mixed  with  slender  septate  threads,  simple  or  branched,  and  called  para- 
physes  (e),  enlarged  134  diameters.  Thus  the  perfect  form  is  ultimately 
reached,  and  it  is  the  canker  fungus,  Nectria  ditissima. 
In  the  perithecium  the  plant  may  rest  a  considerable  time — months,  if 
not  jy^ears,  but  the  spores  are  always  liberated  when  the  external 
conditions  are  favourable  for  development,  and  they,  or  some  of  them, 
always  manage  to  find  out  the  varieties  of  Apples  most  vulnerable, 
including  some  having  the  richest  sap— Ribston  Pii)pin,  Cox’s  Orange 
Pippin,  Golden  Pippin,  and  the  Reinettes.  What  time  the  spores  go 
forth  has  not  clearly  been  ascertained,  but  there  comes  a  right  time  and 
proper  place  for  the  spore  ( F,  enlarged  334  diameters),  on  an  Apple  tree, 
such  as  a  crack,  hole  or  crevice,  and  in  the  one  or  other  it  pushes  a  germ- 
tube  fi’om  one  or  both  cells,  for  it  consists  of  two,  and  the  hypha  (f)  or 
hyphae  (y)  find  access  to  the  tissues  between  the  bark  and  wood,  there 
always  being  a  niche  around  the  circumference  of  .a  wound. 
The  tree  does  its  best  to  cover  the  wound  by  which  the  fungus  germ- 
tube  gains  entrance  into  its  tissues  and  makes  extraordinary  efforts  to 
extrude  the  intruding  organism.  The  result  is  that  the  latter  is  grown 
over  and  gets  firmly  seated  in  the  soft  cellular  tissues  spreading  year  by 
year,  until  it  girdles  the  branches,  and  then  comes  the  end.  It  is  a  bad 
case,  but  there  are  plenty  similar  in  orchards,  yea,  and  in  gardens.  The 
scale  has  covered  the  bark  more  or  less  with  excreta,  and  on  that  was  the 
saprophytic  fungus  called  black  mould,  Fumago  vagans,  shown  at  Z, 
enlarged  134  diameters.  There  was  also  some  lichen  and  moss.  All  the 
overgrowths  may  be  destroyed  by  the  caustic  application  before 
mentioned. 
As  special  applications  for  the  canker  fungus,  after  cutting  off  and 
burning  any  twigs  or  branches  wholly  or  nearly  girdled,  wash  every  part 
with  a  solution  of  sulphate  of  iron,  1  lb.  to  a  gallon  of  water,  applying 
with  a  brush ;  or  spray  with  a  solution  of  sulphate  of  copper,  1  lb.  to 
25  gallons  of  water,  using  as 
much  quicklime  as  sulphate 
of  copper,  so  as  to  get  a 
protective  coating  of  car¬ 
bonate  without  interfering 
with  the  immediate  action  of 
the  sulphate  on  the  fungus. 
This  will  certainly  destroy 
the  conidial  form,  and  even 
young  perithecia,  and,  sink¬ 
ing  into  the  cracks,  do  some¬ 
thing  to  affect  the  mycelium, 
besides  killing  lichenous 
and  mossy  growths.  These 
applications  must  be  made 
whilst  the  trees  are  quite 
dormant,  two  being  best — 
one  as  soon  as  the  leaves 
are  all  down,  and  the  second 
just  before  the  buds  com¬ 
mence  swelling. 
As  dressing  for  the 
wounds,  there  is  nothing 
better  than  a  clay  plaster, 
tenacious  clay  being  dried 
and  pounded  into  powder, 
then  made  into  a  putty  with 
soluble  petroleum,  easily 
made  by  dissolving  I5  lb. 
of  softsoap  by  boiling  in  a 
gallon  of  water,  and  when 
boiling,  but  removed  from 
the  fire,  adding  a  pint  of 
petroleum,  stirring  briskly 
till  amalgamated.  The 
wounds  may  first  be  brushed 
out  with  the  soluble  petro¬ 
leum,  or  preferably  sulphate 
of  cop))er  solution,  1  oz.  to 
gallon  of  water,  and 
then  the  composition  forced 
in,  having  the  stopping 
level  with  the  wound.  The 
petroleum  sinks  into  the 
wood,  gets  at  the  mycelium 
of  the  fungus,  and  kills  all 
it  reaches.  Ylr.  Kruse  was 
the  first  to  I'ecord  the  bene¬ 
ficent  action  of  petroleum 
on  canker-fungus  in  Apple 
trees,  and  in  the  Journal 
of  HorticxUture,  whilst  Mr. 
Allan,  Gunton  Park,  Nor¬ 
wich,  recorded  the  value  of 
the  soluble  petroleum  and 
clay  composition.  This  en¬ 
courages  the  growth  of  new 
bark  over  the  wounds  by 
annual  rings  in  the  directly 
opposite  way  that  the  fungus 
takes  it  off. 
Against  both  scale  and 
fungus  spraying  at  the 
middle  of  iiay,  again  in 
ten  days,  and  a  third  time 
early  in  June  answers  re¬ 
markably  well  with  the 
petroleum  emulsion  given 
above,  diluting  the  whole 
Fig.  44. -Canker  Fungus  on  Apple. 
References: — T,  part  branch  of  Apple  tree, 
showing :  r,  sawn  off  end — soundness  of 
wood  ;  «,  broken  off  end ;  t,  bark  off ; 
M,  bark  on,  living,  but  dried  ;  1 — 6,  rings 
corresponding  to  advance  of  fungus  hyphse ; 
7  and  8,  fungus  and  host  in  final  “struggle 
for  existence  v,  point  of  attack  by  fungus 
by  germ  tube  from  spore ;  10,  outgrowths 
— pustules  of  fungus  on  two-year-old  bark  ; 
.r,  ditto  on  nine-year-old  bark  ;  y,  ditto  on 
inner  bark  of  splinter  of  bark  ;  z,  patch  of 
perithecia  (fruits  of  fungus)  on  old  bark 
adhering  to  scar.  U,  cluster  of  perithecia 
(fruits)  in  crack  of  bark  (enlarged  4  dia¬ 
meters).  V,  perithecium  of  fungus  (magni¬ 
fied  67  times) ;  a,  nipple,  ultimately  de¬ 
pressed.  W,  section  of  perithecium ;  b, 
external  granular  coat ;  c,  gelatinous 
nucleus.  X,  fructification  of  fungus;  d, 
cylindrical  asci,  containing  spores;  e,  para- 
physes  (enlarged  134  diameters)  =  Nectria 
ditissima.  Y,  spore  (magnified  334  times) 
=  fungus  in  embryo;  f  germ-tube  or 
hypha ;  g,  hyphse  (branched  thread) 
=  mycelial  hyphse.  Z,  black  mould  grow¬ 
ing  on  excreta  of  scale  (enlarged  134  dia¬ 
meters)  =  Fumago  vagans. 
(5  quarts,  or  thereabouts) 
to  10  gallons  by  adding  the 
requisite  amount  of  hot, 
soft  water,  and  using  at  a  temperature  of  90  ■’  to  100“  when  the  sun 
is  off  the  trees.  This— 1  in  70 — petroleum  spraying,  answers  well 
against  all  insects  unfixed  by  their  heaks  in  the  plant  tissues,  and 
