ISSUE 11 July 15, 1999
Stay Aware of Aphid Activity and management of these pests of potatoes through this informative site.
Locations that are being monitored are throughout the region,
including northwest Minnesota, Northeast
North Dakota, and several locations throughout ND (Linton, Mandan, Rolette, and Cando).
Currently, one of the most often detected aphids has been the
Bird-cherry oat aphid which has been
very abundant in the regions small grain fields. Some green peach aphid have been collected in Crookston,
Mn and south- central North Dakota (Linton, Mandan). Typically, the aphid captures increase throughout
the region as we reach late July and early August. This coincides with the maturing of grain fields and
general increases in many aphid species in the region.
The aphid species that are known to transmit Potato Leaf Roll and
Potato Virus Y are the Green
peach and Potato aphid. Other aphids that are capable of vectoring Potato Virus Y, though less efficiently,
are bird-cherry oat, corn leaf, English grain, greenbug, sunflower, thistle, and turnip aphids. The aphid alert
updates provide capture information on all these species.
This information is part of a project conducted cooperatively
between the Departments of Entomology
and Plant Pathology and Extension at the University of Minnesota and State Seed Potato programs of
Minnesota and North Dakota. Coordinators of the web site are Robert Suranyi (218) 773- 3346 or
Ted Radcliffe (612) 624-773.
WHEAT MIDGE UPDATE
North Western: Divide - wheat midge increasing, high
night visual counts observed (1 midge/5 wheat
heads to 1 midge/8 wheat heads); Spraying may be necessary. Burke - wheat midge high in Columbus
area. Williams - wheat midge low in Williston area.
North Central: Ward - Minot -Ruthville area - midge
increasing, scout crop in heading stage.
Kenmare area - fields reported with high numbers; spraying will be probably be conducted this week.
McHenry - Anamoose - high night midge counts, 1 midge/1 wheat head. Spraying will probably be
conducted this week. Benson - Oberson (southern Benson area) - high number of midge reported,
fields above economic threshold. Towner - scattered and localized spraying SE of Cando. Ramsey -
generally low numbers of wheat midge reported.
South Central: Wells - fields at economic threshold =
1 midge 4-5 wheat heads, field treatment with
Lorsban common. Foster - low population of wheat midge at Carrington, crop flowering.
Scouting conditions over pass weekend, July 10-11, good due to light
evening winds and warm
evening temperatures near 60 degrees F.
Wheat Midge Alert For: Flight activity is HIGH in
North West and North Central areas like Minot,
Noonan, Columbus, Anamoose, and Devil Lake area (south eastern Towner and Benson County).
Flight activity is DECREASING in South Central areas like Carrington. Night scouting is STILL
CRITICAL in fields that are high risk like wheat on wheat, wheat in the heading to early flowering
stage, and where wheat midge populations are not declining.
Many areas like Bottineau and Renville Counties have none or very
little wheat in the critical stages
of heading to early flowering stage. These counties have traditionally been hot spots for wheat midge.
CORN BORER UPDATE
There are scattered reports from southern counties of light corn
borer larval infestations. There
have been no reports received of spraying yet, only indications of some early shot-holing of leaves
and generally light larval numbers. Moth captures around the region are generally low, but steady.
Monitoring corn fields this week should alert individuals to the possibility of some future problems.
GRASSHOPPER ACTIVITY PICKS UP IN THE
CENTRAL PART OF NORTH DAKOTA
Jan Knodel, NDSU Plant Protection Specialist in Minot, reports
increasing concerns and spraying
directed at grasshoppers in small grains and sunflowers around central North Dakota. Grasshoppers
are increasing in size and mobility the farther we get into the summer. As adults begin to appear in
fields, movement to green vegetation, will become increasingly apparent. As small grain fields ripen,
grasshoppers will move in large numbers to neighboring fields.
LEAFHOPPERS IN DRY BEANS
Potato leafhoppers continue to cause concern in the regions dry bean
fields. Nymphs of the leafhopper
are now present in many fields. Unfortunately, adults are still quite active, also. With the second cutting
of alfalfa underway, adults will be on the move, often migrating into nearby bean and soybean fields.
Treatment thresholds at this time should be when one leafhopper per
trifoliate (combination of nymphs
and adults) are found.
A quick correction to note: The Asana XL label has a misprint
on it. The rate range for potato
leafhopper in dry beans should read: 2.9 to 5.8 fl. oz., instead of 5.8 to 9.6 fl. oz. The lower rate is
the same that appears under the soybean section for potato leafhopper control. This correction was
pointed out by Tim Ulrich of DuPont. Thanks.