Capital press. (Salem, OR) 19??-current, August 21, 2015, Page 9, Image 9

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    August 21, 2015
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CapitalPress.com
9
Idaho late blight outbreak now widespread
By JOHN O’CONNELL
Capital Press
RUPERT, Idaho — High
humidity and continued af-
ternoon thunderstorms have
enabled late blight to prolif-
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a swath of southeast Idaho
encompassing eight counties,
according to potato researcher
Jeff Miller.
Miller, with Rupert-based
Miller Research, is now ad-
vising growers in Minidoka,
Power, Bonneville, Bingham,
Cassia, Madison, Fremont
and Jefferson counties to
spray fungicides weekly —
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roll in and threaten to further
spread the spore load.
Typically, Idaho’s hot and
dry conditions keep late blight
in check.
Miller has encouraged one
grower with severe infection
to kill vines early to limit
the spore load. In most cas-
es, however, he’s found light
infections of the devastating
fungal disease are scattered
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spread in clusters, thanks to
rigorous fungicide programs.
But the even distribution
of lesions — brown patches
often surrounded by light-
green halos — has prevented
growers from controlling the
spread by killing vines in iso-
lated areas.
“As of now, it doesn’t look
like the blight is to the point
of devastation, but you can
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adding it’s become the worst
Idaho late blight outbreak he’s
witnessed since 1998.
In central Minidoka Coun-
ty, where his own research
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blight covering 15 miles from
north to south and 10 miles
from east to west.
Minidoka County crop ad-
visor Gordon Harper has also
increased his growers’ fun-
gicide programs to weekly,
compared with every 14 days
in a normal year, using more
costly but effective products,
and cutting into their already
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“This is the worst I’ve seen
it as far as widespread and
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Harper said.
All late blight samples in
the state have tested as U.S.
23, the same strain found in
the Blackfoot area after heavy
August rains last season. Mill-
er suspects the current Eastern
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time the disease has over-
wintered in Idaho volunteers,
though Magic Valley’s infec-
tions apparently originated
from another source.
The good news, Miller
said, is that U.S. 23, unlike
other strains, is sensitive to
the systemic fungicide meta-
laxyl — though he warns
the chemical works in living
tissue and would be a poor
choice for senescing plants.
Miller has found late blight
has been much slower to in-
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was applied earlier in the sea-
son to control other diseases,
such as pink rot.
Hoping to ensure an ade-
quate chemical supply, Syn-
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Idaho emergency labels for
Ridomil, which contains meta-
laxyl, and Revis as standalone
fungicides in potatoes.
Power County grower Nate
Schroeder, whose crop had late
blight last year, has sprayed a
special gas in empty storages to
rid them of residual spores and
plans to treat spuds with phos-
phorous acid as they head into
storage. He also plans to acid-kill
vines to limit chances of spores
contaminating tubers at harvest.
Though Schroeder has
seen no evidence of late
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son, he’s operating under the
assumption that it’s present.
He’s sticking with a biweekly
John O’Connell/Capital Press
spraying program, however.
“We’re pretty sure it’s -HII0LOOHUZLWK0LOOHU5HVHDUFKLQ5XSHUW,GDKR¿QGVDSRWDWRSODQWZLWKDEURZQOHVLRQVRUURXQGHGE\
out there because it’s every- DJUHHQKDOR²DV\PSWRPRIODWHEOLJKW/DWHEOLJKWKDVEHFRPHH[WUHPHO\ZLGHVSUHDGLQ0DJLF9DOOH\
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