June  6,  1901. 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER 
483 
Brown  Rot  Fungus  on  Apples. 
On  September  17th,  190C,  I,  in  response  to  the  request  of  an 
M.D.  and  F.R.C.S.,  of  whom  I  have  given  name  and  place  of  residence 
to  the  Editor,  inspected  some  Apple  trees  with  fruit  described  as 
rotting  on  them,  and  this  being  the  case,  and  somewhat  of  a  phenomenon 
in  Apples,  I  considered  examples  illustrative  of  the  malady  and  the 
progress  of  the  causing  agent  might  usefully  be  depicted  and  referred 
to  in  the  Journal  of  Horticulture.  The  trees  were  standards,  about 
twenty-one  years  old,  and  occupied  a  sheltered  position  on  the 
south  side  of  (though  some  distance  from)  the  residence.  Soil  a 
gravelly  loam  with  a  somewhat  unctuous  ferruginous  subsoil  and 
underlying  stratum,  incumbent  on  chalk  with  flints.  The  trees, 
evidently  Flower  of  Kent,  were 
laden  with  fruit,  large,  beautiful 
Apples,  and  yet  the  picture  was 
marred  by  very  curious  fruits  more 
or  less  all  over  the  heads,  which, 
though  to  me  very  picturesque  and 
lovely,  spoiled  the  utility  appear¬ 
ance.  Here  and  there  were  hanging 
apparently  quarter-grown  Apples, 
brown,  shrunken,  mummified,  yet 
withal  marked  more  or  less  with 
dense  tomentose  tufts,  often  in 
circles,  fairy-ring-like,  and  in  places 
confluent,  white,  an  example  of 
which  is  shown  in  fig.  1  at  A. 
Half-grown  Apples,  browned,  mum¬ 
mified,  and  with  more  distinctly 
white,  fairy-ring  outgrowths,  were 
still  more  in  evidence  on  the 
trees,  and  all  over  interspersed  with 
the  other  fruit.  An  idea  of  such 
Apple  may  be  gleaned  from  the 
specimen  configured  at  B.  Still 
more  plentiful  were  browned, 
partly  mummified,  three-quarters 
grown  fruit  on  the  trees,  which, 
havmg  the  fairy-ring  white  out¬ 
growths  more  pronounced,  were 
very  conspicuous  amid  the  lull- 
grown  and  highly  coloured  Apples  ; 
this  example  is  depicted  at  C. 
Truly,  as  the  owner  tritely  re¬ 
marked,  the  Apples  were  “  rotting 
on  the  trees.” 
Many  of  the  full-grown  Apples 
had  brown  patches,  usually  one  ou 
each  fruit,  Irom  which — a  point  in 
the  centre  of  the  patch  and  com¬ 
monly  at  the  side  of  the  Apple, 
but  nearer  the  stalk  than  the  eye — 
the  brownness  increased  all  around, 
and  these  fruits  are  greatly  dis¬ 
posed  to  fall  off  the  trees.  On  the 
ground  the  brownness  spreads 
rapidly  over  the  surface  of  the 
Apple,  and  on  the  trees  browned 
and  destroyed  tissues,  the  fairy¬ 
ring-like  outgrowths  of  the  fungus, 
soon  appear,  and  are,  in  my  eyes, 
very  beautiful.  Albeit,  the  affected 
fruit  is  quickly  rendered  quite  useless,  being  browned,  shrunken, 
and  if  dry,  mummified. 
The  rest  of  the  crop  appeared  unaffected  by  the  parasite,  but  on 
many,  in  fact  most,  of  the  Apples,  were  brown  specks,  in  some  cases 
scarcely  visible  to  the  unaided  eye,  otherwise  the  fruits  were  very  fine  in 
appearance.  These  fruits,  after  being  gathered  and  placed  in  the  store¬ 
room,  soon  becomes  brown  all  over,  and  is  thrown  away,  sometimes 
before  the  outgrowths  of  tb.9  fungus  have  appeared.  Of  course  in 
this  I  am  guided  by  the  experience  of  former  years,  the  doctor’s 
wite  assuring  me  that  the  gathered  fruits  always  rotted,  and  unless 
used  as  soon  or  very  shortly  after  picking,  were  not  of  any  value. 
Clearly  we  may  follow  the  whole  course  of  the  fungus  in  this 
instance.  It  began  on  the  small,  newly  set,  and  swelling  Apples.  On 
these  the  summer  spores,  or  conidia,  were  first  produced.  These 
passed  to  the  half-grown  fruit,  and  they  in  turn  had  the  outgrowths 
of  the  parasite  which  affected  the  three-quarters-grown  Apples.  Then 
the  three-quarters-grown  fruit  infested  produced  the  spores  which 
gave  rise  to  the  brown  patches  on  the  full  grown  Apples,  and  the 
action  of  the  parasite  caused  the  fruit  to  rot  on  the  trees  or  in  the  store 
room.  One  point  I  wish  to  emphasise,  namely,  that  on  neither  the 
quarter-grown  nor  the  half-grown  fruits  affected,  A  and  B,  were  there 
any  summer  spores  or  conidia,  hence  one  may  conclude  that  the  summer 
spores  or  conidia  are  produced  once  only — a  crop,  and  no  more — from 
the  diseased  Apples,  and  on  these  there  were  not  found  any  sclerotia 
(small,  black,  wrinkled  bodies),  the  resting  stage  of  the  fungus.  These 
are  produced,  however,  at  the  approach  of  winter,  and  as  a  rule  on  the 
fruits  latest  affected  by  the  parasite.  Such  Apples  are  either  left  on 
the  ground  where  they  have  fallen,  or  those  from  the  store  room  are 
thrown  on  the  rubbish  heap. 
By  the  sclerotia  the  fungus  passes  the  winter.  In  that  form  it  is 
known  as  Sclerotia  fructigena,  the  ascophore  of  which  is  unknown. 
In  the  summer,  when  the  Apples  are  formed,  the  sclerotium  pushes 
flask-shaped  young  mycelium,  and  on  its  short  branches  produces 
globose  conidia  or  first  spores.  These  somehow,  and  by  a  mysterious 
attrahent  power,  find  out  the  host 
plant,  and  the  particular  part  of 
it  which  affords  the  needed  sub¬ 
sistence.  The  Bpores  come  to  rest 
on  the  young  fruit,  push  germinal 
tubes,  enter  the  tissues  of  the 
Apples,  and  anon  dense  tomentose 
tufts,  after  growing  in  circles  and 
becoming  confluent,  appear  on  the 
surface  of  the  affected  fruits,  the 
white  parts  bearing,  on  branched 
hyphse,  elliptical  or  lemon-shaped 
conidia  or  summer  spores — Monilia 
Iructigena.  These  spores  continue 
the  infection  in  “fresh  fields  and 
pastures  new,”  and  finally  the 
sclerotia  or  resting  stage  is  reached. 
The  life  history  of  the  fungus  is 
thus  a  very  simple  one. 
What  do  I  advise  in  preven¬ 
tion  of  brown  rot  fungus  ?  The 
first  essential  to  success  in  com¬ 
bating  this  parasite  is  to  pick  off 
all  infested  fruits  and  burn  them, 
and  continue  this,  whether  on  the 
trees  or  off.  The  fruit  must  not 
be  allowed  to  rot  on  the  trees,  lie 
on  the  ground,  or  be  thrown  on 
the  rubbish  heap.  All  should  be 
carefully  collected  and  burned.  As 
the  spores  from  infested  fruit  are 
scattered  far  and  wide,  some  will 
adhere  to  the  trees,  even  until  the 
following  spring,  when  they  appa¬ 
rently  have  the  power  of  germi¬ 
nating,  bat  how  they  manage  to 
transfer  themselves  to  young  fruit 
is  beyond  human  comprehension, 
for  the  case  is  altogether  different 
from  leaving  mummified  fruit  on 
the  trees  wherein  the  mycelium 
may  remain  in  a  dormant  condition 
during  the  winter,  so  that  in  the 
spring,  during  warm  and  damp 
weather,  this  mycelium  may  pro¬ 
duce  a  new  crop  of  spores,  which, 
being  scattered  everywhere,  may 
develop  in  the  blossoms  and  young 
leaves,  and  is  often  an  unsuspected 
cause  of  the  fruit  not  setting, 
especially  in  stone  fruits,  and  possibly  also  in  Apples  and  Pears. 
Early  treatment  is,  therefore,  imperative.  It  is  well  to  observe  that 
the  Apple  foliage  is  more  susceptible  to  injury  by  a  fungicide  than 
many  other  fruits,  and  that  Bordeaux  mixture  is  still  the  most  potent 
of  fungicides,  though  for  the  Apple  it  must  be  dilute.  A  safe  mixture 
is  formed  of  1  lb.  of  copper  sulphate  and  1  lb.  of  freshly  burned  or 
quicklime  to  12£  gallons  of  water.  It  is  well,  however,  to  err  on  the 
safe  side,  hence  use  the  mixture  at  half  strength  at  the  firBt  two 
sprayings.  Spray  first  before  the  blossoms  open,  tlmn,  as  soon  as  the 
fruit  is  well  formed,  spray  again,  and  repeat  the  application  twice  later 
at  intervals  of  two  or  three  weeks. — G.  Abbey. 
leaves  and  Electric  Eight. — Green  leaves  are  excited  electrically 
by  sunlight.  For  example,  a  young  Iris  leaf  illuminated  by  sunlight 
shows  an  electrical  current  from  the  lighted  to  the  shaded  side,  followed 
by  a  current  in  the  opposite  direction  after  the  illumination  ceases. 
The  Tobacco  plant  behaves  like  the  Iris,  but  in  the  leaves  of  Tropaeolum 
and  some  other  plants  the  electrical  effect  produced  is  in  the  contrary 
direction. 
Beown  Rot  Fungus  on  Apples. 
