The Dolores star., 1911-09-01


0lncs lhs nrst u August there has
bssn gsnssal complaint from the far
msrs throughout the stats Of . disease
whleh hes bsen described = wilt OF
blight. The vines stop growing, the
lsavss roll inward, turn yellow, and
aually become brown and dry. The
vines later undergo similar changes.
when the vines are split the woody
sirsnds which extend length wise Of
the stems and roots are found to bs
brown or black. Frequently. In the
moro advanced stages, the whole plant
rots Cd close to the ground, the rotted
portion appearing soft. black and hol-
low, often with small white worms
present In the decaying tissue. Neith-
Or the soft rot nor the worms are TO be
regarded - directly responsible for the
willing, since both conditions are the
result Of secondary invasion along this
path OF the real cause.
The wilt proper Ii brought about by
fungus, Fusarium Oxysporum which
enterS the plants through the roots
destroying the conducting tissuen, and
grows Into the water tubes OF the
woody strands, filling them 30 com
pletely that II 10 impossible for water
from the soil to reach the stems and
leaves, and willing follows.
In those sections Of the state where
there has been an unusual amount 81
rain, followed by relatively warm
weather, the disease appears to be
much worse, owing to the abundant
growth Of the fungus, which Ii favored
by the wet condition Of the soil. This
mold, or fungus, Ia usually introduced
into the soil by means Of diseased seed
potatoes, and when once established,
It lives there from year to year on de-
caying vegetable matter. 1.-THE tubers
are infected when planted, 1t fire.
quently happens that the young
sprouts are destroyed before they come
through the ground; again, the inva-
sion may be delayed or the progress Of
the disease retarded 10 that no sym
toms Of the wilt appears until the
plants are six to ten inches high, or ~
In the case this year, until the vines
bear half grown potatoes. The tuber
development h seriously interfered
with by the disease, and little, II any
growth takes place after the vines wilt.
The stem end Of the young tubers 10
usually infected, although no indica-
tons Of the trouble may be visible at
the time Of digging. Such tubers de-
velope the well known dry rot In stor-
age, especially II placed In cellars
where there Ii moisture, accompanied
BY high temperature. The develop
ment Of the dry rot, which Is caused
BY the same fungus, can be prevented
BY storing the potatoes In dry cellar
whore the temperature can be held be-
tween SO and 70 degrees r. II should
BE- borne In mind, also, that these in
ternally diseased tubers, which are
used for seed, are the principal means
Of spreading the trouble.
While nothing can be done to check
the epidemic this season, certain con.
troll measures should be taken to pre-
vent Ito reoccurrence aud spread
another year. Spraying has no value
- means Of control since the causal
fungus 10 inside the plant, aud cannot
be reached by fungicide. The dead
vines should all be gathered this fall
and burned. A three to five year rota.
ton, including some leguminous crop
such - alfalfa or peas should be prac.
ticed. This In important for two
reasons: First to increase the fertility
Of the soil, and thereby secure more
vigorous potato vines which will resist
the wilt more effectually; and second,
TO give the fungus an opportunity to
die out. II possible, plant on new land
or on land that has not been In potatoes
for at least five years. A very careful
examination Of the seed should he
made In the spring, aud only sound
tubers used. Seed potatoes which,
when cut, show . brown or black ring
In the vascular region Of the stem end,
OF which exhibit external signs Of dry
rot, should BE- discarded. An excess
Of irrigating water early In the season
should he avoided. The rows should
be ridged high and the water kept 10 "
In the burrows. BY this means the
roots are supplied with abundant
moisture and the excess Ia kept from
the tubcr stems. Late paintings ap-
pear 10 suffer less from the wilt In
some localities than the early ones,
but this h . point that each district
must determine for itself, since the
length Of the season varies greatly