The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1913-08-15
Fungus Diseases May Survive in
Mannro

lHeSS fungus ulS0dS6S also lUI0Cl
the soil and are able to survive there
for three or four years. Furthermore
the germs are able to pass uninjured
through the intestines of stock fed up
on potatoes infected with these dis
eases Thus the diseases may be
spread broadcast in the manure from
those animals.
The "Black Leg" Disease
In some instances the stems and
roots of potato vines were blackened
from the cutting upwards, while the
leaves of such plants were yellow and
=! curied upwards. In these instances it
is probable that the disease was one
known as "black-leg." No treatment
is known which will check or cure
these stem rots, because the affected
portions are underground.
Pull Out and Burn All Diseased Vines
1t is advised that at this time the
potato grower go carefully over the
fields and dig out all vines seen to be
affected with these diseases. They
should then be carried off and burned
If the farmer is unable to do this with
his entire crop, he should rogue
that portion of it intended for seed
purposes and this should be his choic-
est plant.
Value of Seed Selection Shown
Many striking object lessons were
presented in fields visited during the
earlier part of the present month on
the value of care in seed selection,
also on the bad effect of planting po-
tatoes successfully in the same fields.
Amount of Disease and Injury on Seed
Potatoes
Occasion was taken in spring to
make analyses of a number of lots of
seed potatoes from various sources to
ascertain to what extent they were
diseased or injured. The following
figures are impressive especially when
it is borne in mind that they refer to
seed potatoes carefully selected by ex-
tensive growers. 1t is not merely the
run of cellar that is represented.
Powdery dry rot-Russet, 81 per
cent; Burbank SO per cent; Rural.
large, rs per cent; Rural, mixed -
per cent.
Rhlzoctonia scab-Russet, 100 per
cent Burbank, So per cent; Rural,
large, So per cent; Rural. mixed, 80
per cent.
Common scab-Burbank, 16 per
cent; Rural large, per cent; Rural
mixed, 9 per cent.
Sorter injury-Russet, SO per cent;
Burbank, SO per cent; Rural, large,
80 per cent; Rural, mixed, 76 per
cent.
Dumping injury-Russet, 67 per
cent; Burbank, 90 per cent; Rural,
large, g per cent.
Fork injury-Burbank II per cent
1t is true that many of these show
ed but slight degree of injury or
disease, but it was present.
Relation Between Bruised Potatoes
and Disease
The relation of these figures TO
present conditions is very significant.
AS already mentioned it is known
that the powdery dry rot fungus most
ly gains entrance through cuts and
bruises in the skin of stored potatoes,
Here We have ample evidence of the
presence of the disease and of in
Juries to the skin of the potatoes in
great abundance. There is an intimate
relation between the two. It is a pity
that the writer may not reproduce
in his paper photographs showing
to what extent disease has gained en-
trance at the site of wounds: such
pictures would be more impressive
than words.
Object Lessons From the Field
Different portions of a large field
owned by well-known potato grower
has been subjected to varying rota-
lions and planted, respectively, with {
selected an unsolicited seed potatoes.
These will be designed as plats 1, 1
2 and 3.
Successive Potato Planting Establish {
sc Disease in the Soil
Plat 1: Three years in potatoes. 1 s
year in oats, then potatoes in 1913.
Seed not selected. Owner has noted {
Rhizoctonia stem rot in previous sea- {
sons to some extent. BY actual count {
20 per cent of the vines in this plat t
were visibly affected with stem rot. 6
An examination Of the roots of appar- I
emily healthy vines showed many of t
these also to be more or less infected.
1t would be conservative to estimate Q
hat 40 to so per cent of the vines 1
had been attacked by Rhizoctonia. Y
There were Is per cent of missing s