Daily Kennebec journal. [microfilm reel] (Augusta, Me.) 1870-1975, 1920-09-02
ROT FOLLOWING LATE
BLIGHT OF POTATOES
Should the Crop on Blishtins Fields
Be Harvested Immediately Re
suits Of Experiments at Maine and
Vermont Stations Lead t. Advice
Delay the Harvesting"

ShdSiOHS ISaC S0SiCS
Delay the Harvesting"
Orono, Ne, Sept. THE following
vas issued today from the office OF
Charles D. Weeds. director OF the
Iaine agricultural experiment sta
ton at the University OF Maine:
When late blight or rust" occurs
on potato fields more or less rot. par
/ ticulariy on heavy soils. is sure 10
, follow. The Maine Agricultural
Experiment Station IS frequently
asked whether IL IS best 70 dig the
crop al once, where the foliage IS
biighting badly. or 70 delay harvest
ing I'll! some time after the tops are
. entirely dead This question has been
answered BY experimental work done
both b. this and the Vermont sta
ton.
In Maine in 1893 an equal area on
field planted with four early and four
late varieties. both sprayed and un-
sprayed, was dug On September and
October 5 respectively. The potatoes
We're placed in bags and at once
stored in a cool. dry cellar About
January both lots OF each variety
were carefully sorted 70 determine the
total weights Of the decayed and
sound tubers II each
In every case. whether the variety
I vas early or late and whether the
plots on which they grew were IN
sprayed or partially protected from
blight by the Use Of bordeaux mix
ture, the loss was decidedly greater
. in the case Of the early dug and
stored potatoes. The differences
were. of course. more striking where
no spray had been applied. Greater
losses were also obtained in the case
u the early varieties
The record on January l OF the
percentages 9: Joss from rot was
made on the basis OF the total Weld
obtained TOT each variety On each
different date Of digging. The prac-
teal farmer is only interested in
how far Carly or delayed digging in
fiuences the total amount OF MGR
charitable tubers which may be ex-
pected after all the rottins has ap-
peared IN storage. Therefore only
these figures will be given here On
January only about 81 per cent of
merchantabie tubers of early varie-
ties. 50 per cent OF the late or - per
cent merchantab!e OF all varieties
We're obtained where the crop was dug
and stored on September 4. as com
pared with October 8. In other words,
on the average. moro than twice as
much merchantable potatoes were OBJ
tained by delaying harvesting till
after the plants were entirely dead.
than was the case when the crop was
dug while blight was still active on
the foliage and the spores OF the
fungus which causes the rot were be-
ing produced in large numbers.
The Vermont experiments were
made in 1902 and 1908. The first
year the results were obtained from
6 fields on different farms near the
Station. Equal portions of each field
were dug on different dates. from
August 25 to september 80 At least
) varieties of potatoes were repre-
scented. some early. but most late. The
soil on the different fields varied
from sandy loan to heavy clay All
the fields showed blight and some
were badly affected on August IS
On the date of the second digging
September 6. the leaves on the plants
on all the fields but one had been
killed and here they were badly af-
fected. On September rs the entire
plants on all of the fields were dead
The total average per cents of de-
cay for each date of digging. includ-
ing the rot which appeared in the
storage of the first three lots up to
September 80, were as follows: Aug.
%, 35 per cent: Sept. s, 20 per cent:
Sept. IS. 9 per cent; Sept. 80. per
cent. The amount of loss from decay
varied with the character of the soil
where the potatoes were growing, but
the general trend was the same. On
light well drained sandy soil about
10 per cent decay was obtained when
the crop was dug and stored on
August Is, and none occurred in the
last two lots dug. On the other
hand potatoes. grown on a heavy clay
soil dug and stored August %,
showed a loss of nearly IS per cent
from decay up to September 80. while
those which remained in the ground
till this date showed only about 35
per cent decay.
The second years work at Vermont
was carried out on single field Of low
ground. slightly moist and sandy. On
the first date of harvesting the foliage
was from one third to one-half killed
by late blight, on the second date the
leaves were all dead but the stalks
green. on the third the stalks were
practically dead, and on the fourth
the tops were entirely dead. The per
cents of total rot resulting from the
harvesting and storing at different
dates were: Aug. 81. So per cent;
Sept. Z. 26 per cent; Sept. IA, 1S per
cent; Sept. q. II per cent; Sept. %, =
per cent.
While the storage period in the
Vermont experiments was much
shorter than in Maine it will be seen
that the results obtained there are in
entire agreement with those secured
here. It is interesting to note that in
1908 in Vermont. as in Maine. tho
yield of sound tubers was doubled as