ISSUE 2 May 10, 2001
SOYBEAN APHID WATCH - 2001
You may recall that at the end of last year, it was reported that the Soybean aphid, Aphis glycines, had been found infesting soybean fields in the midwestern states of Wisconsin, Illinois, and Michigan. Following the initial discovery, soybean aphids were found in the southeast tip of Minnesota, eastern Iowa, Indiana, and parts of Ohio and Missouri. Some of these later additions to the range of states where they were detected may only be indications of the aphids presence in the fall resulting from winged dispersal, not necessarily survival and establishment for this season.
No soybean aphid were detected in North Dakota last fall. The nearest detection was the southeast corner of Minnesota. There will be an effort to monitor North Dakota fields for soybean aphid this year. The probability of detecting them here is great. The big unknown is when they might arrive and what may happen when they do.
Soybean aphid updates will be made through the Crop and Pest Report. Information on the web is also available through the NDSU Entomology Updates page:
There are several web links that will be of interest. One is the 2001 Soybean Aphid Watch. Maps in the midwest are scheduled to be updated by state representatives that will provide information on detection, population levels, and other comments as the season progresses. This effort is being coordinated by the North Central Pest Management Center and the North Central Integrated Pest Management Program.
The soybean aphid is yellow-green with black cornicles ("tail-pipes") and a pale colored cauda (tail projection). As with other aphids, the soybean aphid is small, about the size of a pinhead. Nymphs would be smaller.
The soybean aphid is the only aphid that will colonize soybean. The aphid is native to Asia. Based on its U.S. distribution in 2000, it has probably been here for more than one season. Because there are no other aphid species that develop on soybean, it is safe to assume that if you see colonies of tiny, yellow aphids on plants, it is Aphis glycines.
If you find aphids in soybeans, contact Phillip Glogoza at 701-231-7581 in North Dakota or Ken Ostlie, U of Minnesota Extension Entomologist, at 612-624-7436. Information requested is:
- Name and contact information (address, phone)
- location of field (county, township, 1/4 section, or GPS latitude-longitude coordinates)
- Farmer (cooperator) if different from above
- brief description of the infestation
It is reported that this aphid feeds specifically on soybean (plants in the Genus Glycine). It is not expected that this aphid would feed on dry bean varieties (Phaseolus spp.). There are other aphids that may be found on dry beans, specifically the Bean aphid, Aphis fabae. This aphid is blue-black in color and has not been a problem in North Dakota.
CUTWORM ACTIVITY - GOOD NEWS FOR NOW
Usually by this time there have been reports from around the state of about cutworm feeding. The first cutworms are Dingy cutworm in the east and Army cutworm in the west. Both these cutworms overwinter as partially grown larvae which become active when soil temperatures warm.
With planting delays in the east due to wet conditions, there arenít significant crop acres where the Dingy cutworms can cause harm. In the west, there has not been a single report of Army cutworm from anywhere, even from states to the south where reports normally occur a month earlier.
For future reference, though we hope the need is limited, here are cutworm treatment guidelines and insecticide recommendations for crops in the region.
Action Thresholds for Cutworms by Crop:
|Canola||1 per square foot|
|Small grain||4 to 5 cutworms per square foot|
|Corn||3 to 6% of plants cut and small larvae less than 3/4 inch present|
|Sugarbeets||4 to 5% of plants cut|
|Soybean/Drybean||1 or more larvae per three feet row or 20% of plants cut|
|Sunflower||1 per square foot or 25 to 30% of plants cut|
|Forage||5 or more per square foot|
Insecticides labeled for treating the above crops for cutworm
Canola ........ Capture.
Wheat ......... Warrior and Lorsban 4E-SG.
Corn ........... permethrin (Ambush, Pounce), Asana, Lorsban, Sevin, and Warrior.
Sugarbeets .. Asana, Lorsban, and Sevin.
Soybean ...... Asana, Lorsban, Pounce, Scout X-tra, Sevin and Warrior.
Dry Bean .... Asana, Sevin, and Orthene.
Sunflower ... Asana, Baythroid, Lorsban, Sevin, and Warrior.
Forage ........ permethrin (Ambush, Pounce), Baythroid, Lannate, Lorsban, Sevin, and Warrior
FOREST TENT CATERPILLARS HATCHING
(see article in Horticulture section)
Phillip Glogoza, Extension Entomologist