Vol.  LXXV. 
NEW  YORK,  MAY  G,  1016. 
No.  4370 
The  Potato  Crop  and  Blight  s>,ra-vcl1  |,l""ts  *“»  "ue  «'»“«  t0  lts  physiological 
effect  on  the  potato  plants. 
Will  it  Pay  to  Spray  ?  DIFFERING  FORMULAS.— The  same  effect 
INCREASING  EXPENSE. — The  question.  “Will  it  ought  to  be  obtained,  therefore,  by  simply  diluting 
pay  to  spray  potatoes  during  the  coming  Sum-  the  5-5-50  Bordeaux  mixture  to  about  a  half  of  its 
mer  with  copper  sulphate  at  50  cents  a  pound?”  has  original  strength.  The  physiological  effect  on  the 
been  presented  to  the  writer  a  number  of  times  dur-  plants  would  probably  not  be  quite  as  much  but  if 
ing  the  past  month.  A  barrel  of  Bordeaux  mixture  the  decrease  in  copper  sulphate  is  not  too  radical 
of  the  strength  recommended  by  the  Vermont  Sta-  there  will  be  little  danger  of  seriously  injuring  its 
tion  for  potatoes  (5-5-50)  will  cost  over  $1.50  for  fungicidal  power.  In  many  parts  of  France  and 
materials  alone,  against  a  cost  of  10  to  50  cents  Germany  a  more  dilute  (2^-2t/^-50)  formula  lias 
of  a  couple  of  years  ago.  If  the  advice  to  continue  been  successfully  used  in  combating  the  downy 
spraying  is  given,  as  it  always  is,  there  always  mildew  of  the  grape  and  the  fungus  is  very  similar 
come  up  other  questions  as  to  possible  substitutes  to  the  one  producing  late  blight.  No  data  seems  to 
for  Bordeaux,  reducing  the  number  of  applications,  be  available  on  the  use  of  lower  percentages  of  cop- 
etc.  It  is  probable  that  there  is  no  immediate  re-  per  sulphate  against  late  blight  on  potatoes.  Ex- 
lief  in  sight  for  the  present  high  price  of  coppei  perhuents  made  at  the  Vermont  Station  during  bad 
sulphate,  and  we  shall  likely  be  paying  30  cents  a  blight  years  with  a  1-1-50  mixture  showed  that 
pound,  or  more,  for  it  for  a  couple  of  seasons  at  while  its  effects  were  beneficial,  it  did  not  entirely 
least.  A  large  part  of  the  copper 
sulphate  used  in  this  country, 
according  to  reliable  news  re¬ 
ports,  has  been  previously  man¬ 
ufactured  in  England  and  im¬ 
ported.  The  present  crisis  lias 
forced  the  English  to  use  all  the 
available  copper  for  war  pur¬ 
poses,  and  there  has  been  little 
to  sliiii  in  the  form  of  copper 
sulphate.  The  wholesale  price 
of  copper  sulphate  in  the  Boston 
market  was  recently  $27.50  per 
hundred  pounds,  and  while  this 
high  price  lias  not  been  main¬ 
tained,  it  will  certainly  not  be 
much  reduced  during  the  coming 
season.  The  American  manu¬ 
facturers  will  be  able  to  supply 
our  demands  for  this  chemical, 
but  the  expensiveness  of  copper 
itself  and  the  increased  Charge 
for  labor  on  this  side  of  the 
water  will  make  any  price  re¬ 
duction  unlikely.  In  view  of 
these  facts  we  must  make  the 
best  of  a  bad  situation.  Are 
there  any  cheaper  substitutes  we 
can  use  instead  of  Bordeaux 
mixture,  or  are  there  any 
changes  in  the  methods  or  appli¬ 
cations  that  will  be  reasonably 
safe  and  yet  a  saving  in  mate¬ 
rials. 
SUB  ST  1 T  l  TTE  COMPOUNDS. 
— No  other  substance  has  been  as 
yet  discovered  that  is  equal  to 
the  copper  compounds  as  cheap 
fungicide  agents.  Lime-sulphur 
is  out  of  the  question.  The 
Geneva  (N.  Y.)  and  Vermont 
stations  have  shown  the  inadvis¬ 
ability  of  attempting  this  substi¬ 
tution;  (lie  Geneva  Station,  even 
found  some  injury  to  result  from 
its  use.  At  the  Vermont  Station 
results  almost  as  favorable  as 
those  obtained  from  the  usual 
5-5-50  Bordeaux  were  obtained 
from  a  combination  of  iron-sill-  Saving  a  Favorite  Apple  Tree  by  Cleaning  Cavity  and  Filling  With  Concrete. 
plutte  and  copper  sulphate.  It  is  probable,  however,  prevent  loss.  The  writer  believes,  however,  that  a 
that  the  iron  sulphate  played  little  part  in  the  fav-  3 14 -2  (4 -50  mixture  thoroughly  applied  will  protect 
arable  effect,  as  iron  sulphate  with  lime  alone  with-  the  plants.  The  method  of  application  is  as  import- 
out  any  cupper  seemed  to  diminish  the  yield.  The  ant  as  or  more  so  than,  the  percentages  of  the  con- 
yields  in  bushels  obtained  in  this  experiment  (1009)  stituents.  High  pressure  sprayers  and  at  least  two 
might  be  of  interest:  nozzles  to  a  row  should  be  used  and  the  rows  should 
Marketable  Small  be  immediately  gone  over  bv  a  second  time  if  the 
tubers.  tubers.  Total.  . 
5-5-50  Bordeaux  mixture...  192  bu.  51  bu.  243  bu.  loll«^e,  and  especially  the  under  leaves  on  which 
Bordeaux  mixture  plus  iron  the  blight  is  likely  to  start,  are  not  covered  with  a 
sulphate  . .  181  bu.  51  bu.  335  bu.  siug[e  application.  At  least  150-200  gallons  per  acre 
(2  lbs.  copper  sulphate,  4  ~  1 
lbs.  iron  sulphate,  6  lbs  lime,  will  be  necessary  to  do  the  work  in  the  manner  m- 
50  gal.  water)  _  dicated. 
Iron  sulphate  with  lime  (5-  , 
5-501  117  in,  m  Bn  if>8  Bn  NUMBER  OB  APPLICATIONS. —  I  he  second  wa> 
5-5-50  Bordeaux  mixture...  192  bu.  51  bu.  243  bu.  1,11,1  especially  me  unuer  leaves  on  which 
Bordeaux  mixture  plus  iron  the  blight  is  likely  to  start,  are  not  covered  with  a 
sulphate  . .  181  bu.  51  bu.  2-j3  bu.  sin<r|ti  application.  At  least  150-200  gallons  per  acre 
(2  lbs.  copper  sulphate,  4  ~  1 
lbs.  iron  sulphate?  6  lbs  lime,  will  be  necessary  to  do  the  work  in  the  manner  m- 
50  gal.  water)  _  dicated. 
5.50  (  .  217  ]n,  bu  168  bu.  NUMBER  OF  APPLICATIONS. —  I  he  second  way 
Control  .  13S  bu.  50  bu.  18S  bu.  in  which  a  saving  may  be  made  is  in  a  cut  in  tlie 
It  must  be  noted  that  the  above  experiments  were  number  of  applications,  provided  the  weather  is  not 
performed  in  a  year  when  no  late  blight  was  found  iavorable  to  blight.  Some  potato  growers  spray  as 
and  are  not  a  test  of  the  fungicidal  properties  of  a  regular  practice  as  often  as  six  or  eight  times 
the  mixtures.  The  increase  in  the  harvest  from  the  during  a  season.  Four  or  live  thorough  applica¬ 
tions  in  the  ordinary  season  ought  to  be  enough. 
These  are  to  be  regarded  as  “insurance”  sprayings, 
and  if  the  weather  is  such  as  to  give  the  late  blight 
a  start,  the  number  will  have  to  be  increased.  The 
potato  grower  will  have  to  keep  a  careful  eye  on  the 
weather  if  be  is  to  reduce  the  cost  of  spraying  to  a 
minimum.  A  spray  program  is  entirely  dependent 
on  tlie  weather  for  its  applicability,  but  the  follow¬ 
ing  one  would  use  as  little  of  the  fungicides  as  pos¬ 
sible  and  the  spraying  would  be  as  few  times  as  is 
safe.  It  would  apply  only  to  Vermont,  New  Hamp¬ 
shire  and  New  York.  Spray  thoroughly  during  the 
early  part  of  July  with  one  of  the  dilute  mixtures 
mentioned  above.  If  the  weather  continues  warm 
and  dry  and  no  blight  appears,  delay  the  next  spray¬ 
ing  until  nearly  the  first  of  August.  A  third  spray¬ 
ing  should  follow  in  two  or  three  weeks  and  the 
fourth  and  last  about  the  first  week  in  September. 
If  the  season  is  very  dry,  the  fourth  spraying  may 
be  omitted,  while  if  tlie  season  is 
very  favorable  for  the  advance¬ 
ment  of  late  blight,  the  spraying 
must  be  more  frequent  and  the 
number  will  depend  entirely  on 
the  apparent  danger  at  the  time. 
LATE  BLIGIIT. —  But  will 
there  be  any  serious  danger  from 
late  blight  during  the  coining 
season  of  1016.  since  that  of  1915 
was  an  epidemic  year  through¬ 
out  the  Northern  States?  Are 
the  chances  not.  good  that:  for 
that  reason  the  infection  may  be 
light  this  year?  To  this  ques¬ 
tion  the  answer  must  be  that  the 
danger  is  much  more  serious  lie- 
cause  of  the  1915  epidemic. 
Many  of  the  potatoes  that  ‘have 
come  from  regions  in  which  the 
late  blight  occurred  have  been 
kept  over  and  will  be  used  as 
seed.  Dr.  I.  E.  Mellius  of  the 
Department  at  Washington  was 
able  to  pick  out  in  Maine,  in 
1914,  40  seed  pieces  infected 
with  late  blight  from  a  single 
barrel  of  seed  potatoes  which 
were  just  about  to  be  planted, 
and  1913  bad  not  been  a  bad 
year  for  blight,  The  late  blight 
fungus  comes  from  these  infected 
seed  tubers,  and  a  single  one  of 
them  might  be  sufiicient  to  start 
off  an  epidemic  that  would  take 
an  entire  field.  Another  source 
of  infection  which  lie  thought 
also  might  be  quite  serious  lies 
in  the  culls  and  tubers  partly 
decayed  by  the  fungus.  If 
dumped  near  potato  fields  they 
may  start  an  epidemic.  Since 
there  are  so  many  diseased  tu¬ 
bers  from  1915,  there  are  so 
many  more  chances  of  an  epi¬ 
demic  starting.  Weather  condi¬ 
tions  must  be  favorable,  of 
course,  for  the  spread  of  the 
fungus  after  it  gets  its  start. 
Fig.  255  but  if  wet,  warm,  muggy  days 
do  come  in  August  and  September,  we  may  again 
expect  to  see  the  blight  prevalent  in  the  northern 
potato  growing  States.  A  study  of  the  situation  in 
Vermont  for  25  years  has  led  to  the  conclusion  that 
the  blight  appears  in  cycles  of  every  six  or  seven 
years,  and  last  year  was  tlie  first  of  a  new  blight 
cycle. 
THE  QUESTION  OF  COST. — The  price  of  po¬ 
tatoes  must  advance  to  a  point  where  their  produc¬ 
tion  is  profitable  whether  they  sell  for  50  cents  or 
$2  a  bushel.  The  probability  is  that  many  growers 
will  be  deterred  by  the  high  price  of  blue  vitriol 
coupled  with  the  previously  low  prices  of  potatoes, 
and  will  not  spray.  The  chances  are  good  as  ex¬ 
plained  above  that  they  will  lose  a  part  or  all  of 
their  crop.  A  shortage  in  the  crop  will  result  as 
it  has  during  the  past  year  in  a  heavy  advance  in 
the  price.  With  five  applications  of  5-5-50  Bor- 
