Aphid Alert: Region-wide virus vector surveillance for
the Minnesota and North Dakota potato industry
Edward B. Radcliffe, radcl001@umn.edu
|
Aphid
Alert 2001, No. 9,
August 10-September 7
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:
Minnesota State Legislature,
Rapid Agricultural Response Initiative &
United States Department of Agriculture,
Cooperative State Research, Education and Extension Service,
Integrated Pest Management Program, North Central Region
WWW address:http://ipmworld.umn.edu/alert.htm
|
 |
Aphid Alert 2001
will not be published on the WWW or sent to e-mail subscribers again until
September 14. However, we will continue to update reporting of aphid
captures on this web site as that data becomes available. To view updated
aphid capture data bookmark this page. |
| Aphid
captures, week ending August 17.
This week's aphid flight activity
remained low in comparison to 2000. No green peach aphid were reported
collected as of August 17 at any of the trapping locations. Essentially,
green peach aphid has not been a factor this year. Most prevalent of
potential PVY vectors were corn leaf aphid, Rhopalosiphum maidis
(Fitch), bird-cherry oat aphid, Rhopalosiphum padi (L.), English
grain aphid, Sitobion avenae (Fabricius), and the sunflower aphid
complex, Aphis helianthi Monell. Turnip aphid, Lipaphis erysimi
(Kaltenbach), was only reported at Linton, ND. Aphid pressure has been
uncommonly low this year so seed potato growers have reason for optimism
that this year's winter tests will bring better news.
Growers in the
Red River Valley are beginning to vine kill. Some will begin digging
next week. Risk of late blight remains very high. On August 17,
NDSU plant pathologists Neil Gudmestad and Gary Secor confirmed the first
2001 instance of potato late blight in the Red River Valley. That
occurred near Lisbon, ND.
Locations for which data were not available when this page was
created will be updated as results are received. One suction trap and two pan traps are operated at each
location, except at Crookston, Rosemount and Thief River Falls which have
more. Data are
reported as total aphid captures per three traps.
|
 |
Captures of green peach aphid per trap, 1992-1994,
1998-2000 (click on figure on left to view larger image).
Abundance of green peach aphid
has differed greatly from one year to the next. In the years
1992-1994 (green lines), captures of green peach aphid were
consistently low; in 1993 only 7 were captured all year. In 1998
and 1999 (red lines) , mean weekly captures were 6 times that of
1992-1994. In 2000 (yellow line), the mean weekly capture rate
was comparable to that of 1992 and 1994. Peak green peach aphid
flight activity occurs in early-mid August, about one week after peak
flight activity of other
potential PVY vectors.
|
|
 |
Comparison of captures of green
peach aphid per trap in 2000
and 2001.
We can now say that 2001
was a repeat of 1993, a year with essentially no green peach
aphid flight activity. The canola is mostly harvested and
never supported the large populations of green peach aphid or turnip
aphid that were common in 1998-2000.
|
|
 |
Captures of PVY vectors other
than green peach aphid per trap, 1992-1994,
1998-2000 (click on figure on left to view larger image).
Abundance
of potential PVY vectors other than green peach aphid have differed
greatly from year to year. Total captures in 1998 were 20 times that
of 1993, and 2-3.5 times that of other years. Species
predominance differed among the years but there were also differences
among locations. Combining data from all dates and trap locations, the
most abundant aphid in 1998 was the sunflower aphid complex, (70% of total captures). In 1999 the most
abundant species was the turnip aphid, (25% of total captures). In 2000 the corn leaf
aphid
comprised 35% of total trap captures.
|
|
 |
Comparison of captures of
potential PVY vectors (other than green peach aphid) per trap in 2000
and 2001.
Corn leaf aphid continues
to be the most abundant aphid in trap captures. We are capturing only small numbers of
bird-cherry oat aphid, English grain aphid, greenbug, and
sunflower aphid. We have captured very few turnip aphids.
|
|
|
Soybean
Aphid,
Aphis glycines Matsumura, continues to spread across Minnesota.
However, heavy infestations are confined to the southeastern portion of
the state.
Most registered
insecticides performed very well in a recently completed
University of Minnesota soybean
insecticide trial. Some growers reported poor
control with pyrethroids applied when air temperatures were
very high.
For more information on soybean aphid in
Minnesota view the Minnesota
Pest Report, August 17.
|
|
|
|
|
|
LATE BLIGHT
ALERT! LATE BLIGHT ALERT!
Roger Jones, Dept.
Plant Pathology, Univ. Minnesota
|
|
Minnesota:The
good news is that there are still no reports of blight. With harvest just
around the corner, this season's crop has been through a lot. The most
evident of this is in the East Grand Forks, Grand Forks and Thompson area,
which have been hit with localized rain and wind that plagued the valley
last week. According to Duane Preston, Extension Agent-Potatoes UMN/NDSU,
the East Grand Forks, Grand Forks, Thompson area has been "severely
hurt with excess water." The outlook in Clay County is the opposite;
conditions there are dry and in need of rain. While Walsh County is
advancing well there are some signs of flea beetle damage. The crop in this
area is in excellent condition. Nearly all regions of Minnesota have now
experienced ideal conditions for the spread of late blight. Please keep a
close watch!! Scout your fields and continue your spray program. Do
not hesistate to contact Roger
Jones (1 888 335 8636) if you have concerns.
North
Dakota:
Late blight has been confirmed near Lisbon in southeastern ND.
Growers in this area should scout fields, continue fungicide
application and have Curzate available to mix with their
protectant fungicide if thunderstorms move through this area. If
late blight is found, please send samples to Plant Pathology,
NDSU for confirmation and genotype determination. Conditions for
late blight remain favorable in all irrigated sites and for
Stephen and Prosper at the non-irrigated sites, but for the
other non-irrigated sites, conditions remain unfavorable for
late blight development the past few days. Conditions have been
quite favorable for early blight, and despite repeated
applications of fungicide, early blight seems to continue.
Additional fungicide applications or the addition of a tin-based
fungicide may help with the late season early blight.
Wisconsin: The
humid and cooler weather of the past week provided favorable
conditions for additional spread of late blight. IPM scouts are
reporting additional fields with symptoms of late blight. While
the general scenario is a few infected leaves here and there,
the distribution of late blight throughout central Wisconsin is
a concern. Long periods of high relative humidity and leaf
wetness could pose problems for containment of late blight as we
move into the last month of maintaining foliage health. The area
of late blight concern also continues to expand with late blight
as far south as Coloma and north to the Antigo area. Fungicide
spray programs should continue on a 5-7 day interval until vine
kill. For the most part, control of late blight has been
excellent. This was achieved by careful, but not excessive use
of fungicides to maintain protection of all foliage as we have
moved through the growing season. Severity values have increased
substantially during the past week, especially in northeastern
WI. Growers should plan their spray programs accordingly.
|
|
| To
subscribe
or unsubscribe to Aphid Alert 2001
To become an e-mail subscriber send us an
e-mail message with the word "subscribe"
in subject line. We
have taken the liberty of adding many names to our e-mail subscriber
list. 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 want to receive
messages in HTML format; if so, reply with "TXT"
in the subject line..
|
|
Send comments or inquiries regarding this page to Ted Radcliffe.
Return to top of this page
Return to opening menu of Radcliffe's IPM World Textbook
The University of Minnesota is an equal opportunity educator and employer.
Last modified: Friday, August 17, 2001
© Regents of the University of Minnesota, 2001
|
