Pueblo chieftain., 1921-10-17
WESTERN POTATO
CULTURE SERIOUSLY
MENACEO BY MOSAIC

A survey OF the western states con-
Quoted during the past summer by
pathologists of the United States De-
partment of Agriculture shows that
elimination of the mosaic disease of
potatoes are taken Immediately the
work. OF potato seed improvement in
the west will soon become extremely
difficult. IL at all possible. Being of
, an infectious nature, the disease is
| spread in the field thruout the sum
| mcr by means of insects which carry
| 1t from diseased to healthy plantss and
Is also transmitted with the seed
| tubers from one generation to another.
There is no evidence that plant once
| infected can recover and produce a
healthy progeny at any time. On the
contrary, the infected plants ordinarily
tend to very rapid deterioration.
under certain environmental condi-
tions practically cease to produce
| tubers in the third or fourth genera
tion. If only "A partial wedding out Of
the worst cases is practiced. the stu
alton may be somewhat improved, tho
not in all cases and by no means per-
| manenty. Tho mild and the medium
| stages of the disease left in tho stock
serve as perpetual sources Of Infection.
and eventually the entire strain be-
comes diseased and is apt to run out"
| completely.
1t has been repeatedly demonstrated
In the cast that the average reduction
Of yield due to mosaic Is about 30
per cent Precisely the same effect OF
this disease was noted in tho case Of
all the varieties grown In different
western states. Some remarkable in
| stances were observed during the last
| two years of field observations carried
| on by. the department In which the
reduction of yield In individual hills
was In direct proportion to the sever
ity OF the infection.
Tho potato acreage in certain irri-
gated sections of the west has been
compared with that of the last year,
yet tho yield In these districts is only
two thirds of the normal. Many
growers complain that where 900 sacks
or more werc raised to the acre In
former years. only 100 to $50 sacks are
obtainab1e now. This is in fields un-
der good cultural conditions. showing
good stands and a high freedom from
fungus and bacterial diseases. Tho low
yielding quality OF the strains in
manifestation of mosaic. Tho need of
good seed In the west Is we'll recog-
nized and is growing every wear. vet
only n meagcr quantity of even rcla-
lively good seed is obtainable.
There is vcry little, II any. hope Of
potatoes. the department specialists
think: therefore. prompt efforts should
be made to locate the most healthy
strains OF tho various important COM
mercial varieties. Since there is no
means at present of detecting mosaic
on the tubcr the search should be
confined exclusively to the fields dur
ing the growing season. When the best
strains are found they nhould further
be improved by the annual elimination
of all the diseased individuals.
1t is necessary to place this work
3 In charge of ht0hlv frQtnaH rnCria OF 10
since the Identification OF certain
minute and peculiar characters Of the
disease requires considerable exper-
ience and great deal OF pathological
knowledge. Furthermore. manifesto
tions of mosaic under the varied cul-
tural and climatic conditions OF tho
west arc often very obscure and not
yet fully Understood.