Aphid Alert 1999, No. 3, June 29

Summer 1999: Aphid trapping data

Results reported in this issue of Aphid Alert are total captures of winged aphids and species identifications for the following locations and sampling interval end-dates. Missing locations will be incorporated in this issue of the newsletter when available.

During the past week, total aphid captures were ~25% greater than in the week previous, i.e., 20.4 aphids per location compared to 16.3 aphids per location. Bird cherry-oat aphid, Rhopalosipum padi (L.), was, for the second week, the most abundant aphid captured in the traps, but as percentage of total aphid captures, bird cherry-oat aphid declined from 53.4% to 35.3%. Green peach aphids were captured at three locations, Baker (2 aphids), Crookston (1 aphid), and Karlstad (2 aphids). Dr. Lockhart tested the green peach aphids and found that they were not carrying potato virus Y (PVY) or potato leafroll virus (PLRV).

The first aphid immigrants arriving in a potato field usually are not carrying potato viruses since they originate from host plants other than potato. If the aphid acquires virus from a potato grown from an infected tuber, they may spread that infection to nearby healthy potato plants. If the initial infection rate is low, e.g., <1%, rogueing can be effective control measure. Roguing should be done as soon as possible and the infected vines removed from the field.

Insecticides are not very effective in preventing primary virus spread, i.e., virus coming from sources outside the protected field, because no insecticide kills quickly enough to prevent transmission. Insecticides can prevent the potato colonizing aphid species, e.g., green peach aphid, potato aphid, and buckthorn aphid, from becoming established and spreading virus within the potato crop. Insecticides can reduce secondary spread, i.e., movement of the virus from an infected plant to nearby healthy plants. Insecticides tend to be more effective at preventing the spread of leafroll (PLRV) than in preventing spread of mosaic (PVY). For more discussion of chemical control of potato virus spread see Aphid Alert, No. 4, 1998.

We maintain a list of e-mail addresses to facilitate communication with those of you interested in receiving updates about this research or any resulting advisories sooner than this information can be delivered by mail or even before it is posted on the WWW. If you wish your name added to receive such messages please send us an e-mail at radcl001@umn.edu. In the message, write "Aphid Alert subscribe."

Errors: If you find errors, typographic or factual, we would appreciate having them called to our attention so they can be corrected. Phone: Robert Suranyi (218) 773-3346 or Ted Radcliffe (612) 624-773 or send an e-mail to radcl001@umn.edu.

 

Results

Minnesota: Baker, Climax, Crookston, Gully, Hollandale, Karlstad, Little Falls, Morris, Williams
North Dakota: Cando, Hoople, Linton, Mandan, Rolette, Walhalla

Baker, MN, week ending 29 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid 2 4.4
  potato aphid 1 2.2
       
PVY vectors bird cherry-oat aphid 21 46.7
  corn leaf aphid    
  English grain aphid 1 2.2
  greenbug    
  sunflower aphid    
  thistle aphid 2 4.4
  turnip aphid 10 22.2
       
Identified non-vector species      
       
Unidentified   8 17.8
  Total 45  

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Climax, MN, week ending 28 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid    
       
PVY vectors bird cherry-oat aphid 8 66.7
  corn leaf aphid    
  English grain aphid 1 8.3
  greenbug    
  sunflower aphid    
  thistle aphid    
  turnip aphid    
       
Identified non-vector species      
       
Unidentified   3 25
  Total 12  

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Crookston, MN, week ending 28 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid 1 3.3
  potato aphid    
       
PVY vectors bird cherry-oat aphid 24 80
  corn leaf aphid    
  English grain aphid 1 3.3
  greenbug    
  sunflower aphid    
  thistle aphid    
  turnip aphid    
       
Identified non-vector species   1 3.3
       
Unidentified   3 10
  Total 30  

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Gully, MN, week ending 28 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid    
       
PVY vectors bird cherry-oat aphid 3 14.3
  corn leaf aphid    
  English grain aphid    
  greenbug    
  sunflower aphid    
  thistle aphid    
  turnip aphid 1 4.8
       
Identified non-vector species   13 61.9
       
Unidentified   4 19.1
  Total 21  

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Hollandale, MN, week ending 30 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid    
       
PVY vectors bird cherry-oat aphid 7 63.3
  corn leaf aphid    
  English grain aphid    
  greenbug    
  sunflower aphid    
  thistle aphid 1 9.1
  turnip aphid 1 9.1
       
Identified non-vector species      
       
Unidentified   2 18.2
  Total 11  

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Karlstad, MN, week ending 29 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid 2 9.5
  potato aphid    
       
PVY vectors bird cherry-oat aphid 4 19.1
  corn leaf aphid 6 28.6
  English grain aphid    
  greenbug    
  sunflower aphid    
  thistle aphid 4 19.1
  turnip aphid    
       
Identified non-vector species   1 4.7
       
Unidentified   4 19.1
  Total 21  

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Little Falls, MN, week ending 29 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid 1 3.03
       
PVY vectors bird cherry-oat aphid 16 48.5
  corn leaf aphid    
  English grain aphid 3 9.1
  greenbug    
  sunflower aphid    
  thistle aphid 2 6.1
  turnip aphid 5 15.2
       
Identified non-vector species   2 6.1
       
Unidentified   4 12.2
  Total 33  

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Morris, MN, week ending 28 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid    
       
PVY vectors bird cherry-oat aphid 12 19.1
  corn leaf aphid    
  English grain aphid 1 3.1
  greenbug 2 6.2
  sunflower aphid    
  thistle aphid 1 3.1
  turnip aphid 9 28.1
       
Identified non-vector species   1 3.1
       
Unidentified   6 18.8
  Total 32  

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Williams, MN, week ending 29 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid 1 7.7
       
PVY vectors bird cherry-oat aphid 4 30.8
  corn leaf aphid 1 7.7
  English grain aphid    
  greenbug    
  sunflower aphid    
  thistle aphid    
  turnip aphid    
       
Identified non-vector species   3 23.1
       
Unidentified   4 30.8
  Total 13  

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Cando, ND, week ending 29 June

Data not available

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Hoople, ND, week ending 29 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid 1 16.7
       
PVY vectors bird cherry-oat aphid    
  corn leaf aphid    
  English grain aphid    
  greenbug    
  sunflower aphid    
  thistle aphid    
  turnip aphid    
       
Identified non-vector species   2 33.3
       
Unidentified   3 50
  Total 6  

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Linton, ND, week ending 27 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid 7 14.9
       
PVY vectors bird cherry-oat aphid 3 6.4
  corn leaf aphid 2 4.3
  English grain aphid 1 2.1
  greenbug    
  sunflower aphid 1 2.1
  thistle aphid    
  turnip aphid 11 23.4
       
Identified non-vector species   6 12.5
       
Unidentified   16 34
  Total 47  

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Mandan, ND, week ending 27 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid 3 8.3
       
PVY vectors bird cherry-oat aphid 6 16.7
  corn leaf aphid    
  English grain aphid 2 5.6
  greenbug 1 2.8
  sunflower aphid 4 11.1
  thistle aphid    
  turnip aphid 4 11.1
       
Identified non-vector species   9 25
       
Unidentified   7 19.4
  Total 36  

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Rolette, week ending 29 June

Data not available

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Walhalla, ND, week ending 24 June

  Aphid species # captured % of total capture
PLRV/PVY vectors green peach aphid    
  potato aphid    
       
PVY vectors bird cherry-oat aphid 1 16.7
  corn leaf aphid    
  English grain aphid    
  greenbug    
  sunflower aphid 1 16.7
  thistle aphid    
  turnip aphid    
       
Identified non-vector species      
       
Unidentified   4 66.7
  Total 6  

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