Aphid Alert: a research/outreach program providing region-wide virus vector surveillance
to
the Northern Great Plains potato industry
Edward B. Radcliffe, radcl001@umn.edu
Aphid
Alert 2002, No. 7,
August 16
Published cooperatively by
the
Department of Entomology,
College of Agricultural, Food & Environmental
Sciences,
University of Minnesota, the
University of Minnesota Extension
Service,
and the State Seed Potato Programs of Minnesota and North Dakota
Project funding
provided by:
the Northern Plains Potato Growers Association,
the Minnesota State Legislature,
Rapid Agricultural Response Initiative
&
the
United States Department of Agriculture,
Cooperative State Research,
Education and Extension Service,
Integrated Pest Management Program, North Central Region
WWW address:
http://ipmwor
ld.umn.edu/alert.htm
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Contents
Aphid
Situation in Week Ending August 16 |
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Aphid
Situation in Week Ending August 16
Aphid flight activity was lower across the Northern Great
Plains during the week ending August 16th than in the week previous.
Cumulative mean green peach aphid captures per trap remain in the
low to moderate range throughout all regions in the Aphid Alert
network. At the University of Minnesota Rosemount
Agricultural Experiment Station, green peach aphid populations are
highly resistant to organophosphate insecticides and have reached
densities of hundreds per leaf in plots sprayed with
azinphosmethyl (Guthion). Growers should be cautious in
choosing insecticides to control this pest. The most
effective foliar insecticides for green peach aphid control in our
insecticide efficiacy trials have been methamidophos (Monitor),
pymetrozine (Fulfill), thiamethoxam (Actara ) and imidacloprid (Provado).
We have observed that green peach aphid colonies are becoming
established in potatoes treated with systemic insecticides at planting.
At this time, most green peach aphid are found on field margins.
In one 160 acre field located near Hoople, ND, we found 97% of all
colonizing green peach aphid within 60 ft (18 m) of the field
margin and 80% of those within the first 20 ft. All growers,
including those who used systemic insecticides at planting, should
scout their fields regularly for green peach aphid.
Border treatments, e.g., 1-2 passes of an airplane or equivalent
ground spraying may be good insurance for seed potato growers even
if green peach aphid is not detected. Seed potato fields
that can be harvested should be killed as soon as possible to
reduce the risk of virus spread. While green peach aphid
pressure is low to moderate, PVY vectors are abundant this year.
Bird cherry-oat aphid abundance has been greater than in any
previous year of the operation of the Aphid Alert network.
Greenbug is also more abundant than usual. Both of these
cereal aphids are efficient vectors of PVY. Flight activity
of these aphids peaks as small grains mature. The turnip
aphid has been very abundant in 2002. This aphid is also a
vector of PVY, although apparently not very efficient. With
the maturation and harvest of small grains and canola we
anticipate the abundance of cereal aphids and turnip aphid will
decline sharply. |
| Weather Conditions and
Late
Blight The Northern Great Plains region (Manitoba, Minnesota and North Dakota) continues to dodge the potato late blight bullet. That reflects well on the diligence of the region's potato growers in maintaining regular applications of protective fungicides. As the season progresses and evenings become cooler it is important that growers continue to scout their fields and make regular fungicide applications. Cool nights increase the probability of dew formation which provides favorable conditions for potato late blight development and spread if the inoculum is present. Weather conditions can change rapidly so the maintenance of protective fungicidal residues is imperative. Conditions have been highly favorable for late blight for much of the growing season and nearly all areas where potatoes are grown have cumulative Disease Severity Values (for the season) that exceed the alert threshold. Potato late blight status reports |
| Subscriber
Alert This is the seventh issue of Aphid Alert 2002. This newsletter is intended to alert seed potato producers in the Northern Great Plains to flight activity by aphid species that are known to be potential vectors of potato viruses. We report results weekly on the WWW, by e-mail to subscribers, and by surface mail to all Minnesota and North Dakota seed potato growers. The hard copy and e-mail versions of Aphid Alert report aphid capture data available as of the date they are mailed. The WWW version is updated as additional data becomes available. To become an e-mail subscriber, send us an e-mail message with the word "subscribe" in subject line. If you have no interest in receiving this newsletter by e-mail, please reply with the word "unsubscribe" in the subject line. Some e-mail subscribers may not wish to receive messages containing graphics. If so, reply with the the words "no graphics" in the subject line. |
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Minnesota locations: mean aphid captures per
trap during the week ending August 16 |
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North Dakota locations: mean aphid captures per trap during the week ending August 16
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Manitoba locations: mean aphid captures per trap during week ending August 16 (see Manitoba Agriculture and Food Website)
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Wisconsin, South Dakota and Nebraska locations: mean aphid captures per trap during the week ending August 16
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Figure: Trap locations in the Aphid Alert network in 2002
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Figure: Cumulative captures of green
peach aphid (per trap), 1992-1994, and 1998-2001. Three
distinctly different seasonal patterns of green peach aphid
abundance have been observed. In 1998 and 1999 green peach
aphid were abundant with total captures approximately an order of
magnitude greater (10X) than that of 1992, 1993 and 1994, and two
orders of magnitude greater (100X) than that of 1993 and 2001.
For the Minnesota and North Dakota seed potato industry, low
green peach aphid pressure in 1994 coincided with the end of a
multi-year PVY epidemic and the low green peach aphid pressure of
2001 coincided with the end of a multi-year epidemic of PLRV.
Green peach aphid flight activity through August 16 of 2002
remains moderate to low.
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Figure: Cumulative captures of
bird cherry-oat aphid (per trap), 1992-1994, and 1998-2001.
This aphid comes off wheat and other cereals. The species is
typically abundant in the Northern Great Plains. In
our area, green peach aphid and bird cherry-oat aphid appear to be
the two most important vectors of PVY. Lowest abundance of
bird cherry-oat aphid during the years the Aphid Alert network has
operated was in 1994, which coupled with low green peach aphid pressure, coincided with the end of a multi-year epidemic of PVY.
Bird cherry-oat aphid flight activity has been higher in 2002 than
in previous years of the Aphid Alert network.
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Figure: Cumulative captures of
bird cherry-oat aphid and green peach aphid (per trap), 1992-1994, and 1998-2001.
These two aphids have been implicated as the primary vectors of
PVY in the Northern Great Plains (see
Aphid
Alert 2002, no. 2). Other potential
vectors of PVY,
e.g., greenbug and turnip aphid are also abundant this year.
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Report on progress of research on green peach aphid migration University of Minnesota Ph.D. student Min Zhu will present a
report on the progress of her Ph.D. thesis research at the
upcoming
15th Conf. on Biometeorology/Aerobiology and 16th Congress of
Biometeorology in Kansas City, MO, October 27-Nov.1, 2002.
An
extended abstract of her work is available on that
organization's meeting web site (Acrobat
reader is required to view the file). |
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Ted Radcliffe Last modified: Friday, August 16, 2002 © Regents of the University of Minnesota, 2002
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