Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-07-22

Gardeners who have been hav-
ing trouble with their potato plants
this summer are for the most part
paying the penalty for failure to
buy certified seed, and for failure
to rotate their planting in differ
emit parts of the garden each year.
This was announced by Dan
Thurber, Cascade county extension
agent, following widespread in
spections of potato paintings in that
area by himself and E. E. Isaac, state
extension horticulturist.
Although practically every potato
grower whose vines are willing is dead
certain that his plants are suffering
from purple top" not a single case
of this blight has been found in Cas-
cade county, Thurber said.
Much of the trouble reported by Cas-
cade county growers Is due to their
purchase this spring of Early Ohio
potatoes which were ordinary CONNER
cial stock, not certified seed, and APP
ailments which have been showing up
in local potato patches this year, Thur
Der said AS a remedy for 1910, he adj
Yised purchase Of locally grown Bliss
Triumph certified seed, plus rotation.
Suffering From Mosaic
Most willing potato vines In the
Cascade county area are suffering from
mosaic" so called because the wilted
leaves, held to the light, bear an easily
distinguished notified appearance. The
disease was In the seed and grows
gradually in intensity through the
summer 1t infects the ground in which
the diseased seed Is sown, and may
also be carried by insects from dis
eased plants to healthy plants. The
leaves turn yellow and curl when the
disease nears It's zenith
Another potato malady found this
year is flIserium wilt, due TO diseased
seed. 1t may be identified by a black
ring In the seed Plants afflicted grow
normally, then wither and die within
q few days, when the disease makes It's
way into the plant sap system. No
remedy Is known.
Some plants have also been found |
10 be afflicted With rhysoctonia. The |
potatoes Of plants so affected will be |
found covered with spores, which ap- |
pear to be small black specks. Similar |
specks will also be found on the roots, |
Just below the surface. Plants afflicted |
are dwarflike. There Is no cure, al |
,hough the blight may be cleared from |
infected seed by treating before plant
ing.
Cause Of Purple Top
Purple top, the affliction which most
growers think is harming their po-
satoes, is caused by the bite of a tiny
insect, and sby the bite of its larvae.
The insect, technically known as q
psyllid, is dark-winged in its adult
stage, and Is about a 10th Of an inch
IN length. 1t has transparent wings
which fold back on its body. The adult
Insects take flight when approached
and are almost never seen by curSory
observers, Thurber said.
The larvae, however, may be found
IN the under side Of the leaves. They
ire about twice as large as an ordinary
and are light yellow in color.
Both the adults and the larvae suck
he sap of the potato vine and when
,uncturing the leaves, inject a Yirulent
liant poison into the sap system This
auses the leaves to curl and die and
educes the potato yield severely. Once
he plants have been poisoned, there
5 no remedy. The disease may be pre-
ented by spraying the plants before
dvent of the insects. Thus far this
ear, Thurber said, there is no indi-
alton that the insects are sufficiently
revalent in Cascade county to warrant
he expense of spraying.