Rocky Mountain husbandman. [volume] (Diamond City, Mont.) 1875-1943, 1883-09-27

damage in many vineyards is a close rela-
I'VE OF the potato rot They both belsng 10
the same genus (Perenospora). genus
which contains a large number of species.
and all are destructive TO the host plants.
The potato rot fungus consists of long
hlaments or threads. which grow through
the substance Of the potato plant, and rob
it of juices and induce rapid decay. The
fungus usually makes its first appearance on
the under side Of the leaves as frost.like
patches. soon causing the foliage to curl
and turn brown. This frost-like appearance
is due to multitude Of spores which have
formed upon the ends of fangus threads
protruding from the breathing pores Of the
leaf. There are many thousand stomata or
breathing pores TO the square inch. and a
dozen or more threads may come out at
each opening. Each of these threads form
branches, and each branch bears spore.
This helps to give an idea OF the vast num-
ber OF spores formed upon single affected
leaf. These spores germinate quickly and
in peculiar manner-each spore giving rise
to several smaller spores. provided with
hair-'ike appendages (cilia). by means of
which they move quickly around. This is
a most admirable provision for the rapid
and perfect spreading OF the disease when
it has once struck potato field 81
After the foliage has become affected the
disease passes into the stems and down to
the tubers. when the most destructive work
is done. The farmer should be on the watch
fer this fatal pest Of his potato field. Like
most fungi. this Peronospora thrives best in
warm, rainy, or "muggy" weather.. In one
of the recent press reports it was stated
that the decay was caused by the wet wea-
ther which has prevailed in many parts Of
the country. The weather was only ia
voring condition for the growth of the rot
plant, as much SO as the rains are aids to
the profitable development of the various
field crops. Weeks age we predicted, ard
with great degree of certainty, that the
potatoes would rot In many sections. This
came from knowledge of the nature Of the
rot and the conditions which favor its de-
velopment.
1t has been shown that the disea e is first
seen upon the leaves. When the foliage be-
gins to curl and turn brown, the potatoes
should be dug at once. and in this prevent
the fungus from reaching the tubers. The
potatoes should then be placed in cool and
dry place-the conditions least favorable tor
the further growth of the fungus shonla 1t
be present. All affected tubers should be
thrown out and gathered with the vines and
burned. This destroys multitudes of spores,
which might otherivise live through the
winter aad be ready 10 propagate the rot the
following season.
There has been great deal said about
''rot proor' varieties OF potatoes, but they
probably do not exist Some sorts are more
susceptible than Others, probably from con-
stitutional weakness. Many prizes have hern
offered In Eng land for the finding Of the best
sorts to withstande ethe attacks of the rot
fungus, but withouIany satisfactory results.
Knowing that the disease is caused by a
parasitic fungus, the rapid development of |
which is favored by moist. warm weather.
there is little hopeof finding variety of
potatoes so abnormal as to be rot proof
Scientific Anaericam.
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