The Bemidji daily pioneer. [volume] (Bemidji, Minn.) 1904-1971, 1920-03-08
TREAT Ri: 4 DISEASES j /! i
OF onion PLANT
Smut Works Overtime in Trying
to Snuff Out Young Seedlings
\ by Forming Biisters.
FUNGUS CAUSE OF AILMEN1

Control Of Trouble 10 Accomplished BY
Changing Location Of Bed to
:: Clean solI-Aiso Plant Sets
:, Instead Of Seed.
prepared BY the United States Depart.
msnt Of Agriculture.)
Maybe it is because Of its strong
Uen. Anyway there is some mag
net1c attraction which apparently
draws disease Of various kinds and
conditions to the onion crop. Take,
for instance, onion smut. It WORKS
overtime In trying to snuff out the
young seedlings by forming brownish
black, elongated blisters which finally
split the leaves and expose the pow.
1ery black mass Of spores within the
interior Of the blister. A specific
fungus causes this onion ailment, tho
spores wtntering in tho ground and
again attacking the young sesdlinSs IN
Ne spring.
The onion is susceptible to the fun
4as only while in the young Seeding
stage. After the plants reach height
u three to four inches they become
fDnane to further infection. Smut
spreads slowly in the soil, but IN
infested area In 4 neld will gradually
becone larger and more severely dis
9ased each year onions are grown On
soeA IN area. The spores are spread
q farm implements, the feet Of men
a11 animals, By surface water, and IN
dust carried BY the air. Purchasers
q snion sets should use caution that
they do not contaminate the soil by
planting smutted sets.
Control IL accomplished In homo Gar
1s1s By changing the location OF the
enioa bed to clean soil, or BY planting
sets instead Of seed. In large COM
nercial onion districts Of the northern
states formaldehyde solution Is ap-
piled in the furrow with the seed, 40
this disinfectant holds the fungus in
check. One fluid ounce Of 81 to 40
per cent for1naldehyde solution Is used
with each gallon Of water, this diluted
solution being applied at the rate OF
200 gallons per acre or gallon to 1856
feet Of row. Farmers bulletin No.
1850, recently issued by the United
States department Of agriculture, de-
scribes In detail the apparatus used In
applying this Notwithstanding seed
protector. As rule, it costs about
IS an acre to insure the onion crop
against smut losses in this manner. It
is advised that the tops of diseased
onions be burned after harvest in Or
der to prevent the return Of infected
onion refuse to the soil. The spread
Ing Of waste from onion warehouses Is
a bad practice.
A Destructive Plant Disease.
Onion mildew or blight is some
times serious in the cooler and more
humid onion districts. The disease
commonly starts in the field in spots
and spreads to the surrounding areas,
its development being greatly aided by
moist weather. 1t centraliZes its at
tack on the leaves, which turn yellow,
become covered with furry growth,
and eventually collapse. The disease
occurs wherever onions are grown ex-
tensively, although the control varies
in different sections. A fungus causes
the disease. the furry masses on the
affected leaves being branches of the
fungus, which bear abundant spores.
Warm weather promotes spore ger
mination, and hence is favorable to
tho SprnnI If tho disease
As the spores winter in the onion
field, an efficient crop rotation is one
commenduble method of control, the
supplementary growing of cahbages.
potatoes. and sugar beets with onions
being valuable. Good soil drainage
also helps to reduce the blight. since
it decreases the moisture in the air
near the surface Of the soil. Good
air drainage of the fields is also eS-
Sential 50 that excessive dew and fog
may be avoided. RoSin fish-oil soap
as Il sticker, makes the use Of bOr-
dcaux mixture effective in controlling
onion mildcw. The bordeaux mix
ture consists of four pounds Of cop
per sulphate. four pounds of quick
lime, three pounds of rosin fish-oil
soap, mixed with water to make a 81
gallon solution. Complete directions
for making this spray are furnished
in the department Of agriculture bull
letin.
Onion leaf mold is a disease Of
minor Importance except in Louisiana
and California, where it occasionally
causes large losses. 1t occurs in
mid-season and causes the tips Of the
leaves to die back. No satisfactory
control has been perfected.
Strict attention to sanitary meas
ures and careful sorting Of diseased
bulbs at harvest time are the chief
means of controlling Fusarium rot,
which reduces the roots to mass
Of white mo]dy growth.
Onion smudge, confined largely to
the white varieties, results in a
smudgy, unsightly appearance of the
bulbs and an ultimate reduction In