Aphid Alert 2000, No. 10, August 13

Update: Summary of virus vector situation through 13 August

Captures of winged aphids in the Aphid Alert network traps were roughly double that of last week (144.5 per trap compared to 74.3). Captures of green peach aphid averaged 1.19 per trap compared to 0.55 per trap last week. Some locations in North Dakota averaged 3.0 green peach aphids per trap. Turnip aphid numbers also increased about 4.5-fold (to a mean of 19 per trap). Green peach aphid and turnip aphid are commonly found in large numbers on canola. Most canola has been swathed, but late planted fields still host high numbers of green peach aphid and most of the immatures will develop into winged adults. Corn leaf aphid remains very abundant in many locations, but this species is not important as a PVY vector.

Last week, we noted reports of an aphid attacking soybean in Michigan and Illinois. It since has been determined that this aphid is Aphis glycines, an Asiatic soybean pest. This unwanted immigrant is very similar in appearance to Aphis gossypii (melon or cotton aphid). Aphis glycines is native to northern China and Siberia so it unlikely to be limited by cold winter temperatures. We suspect that Aphis glycines will prove capable of transmitting PVY. That might reduce the value of soybean as a crop border for protection of elite potato seed lots from PVY, but small grains have proven effective as crop borders even though they host aphids capable of vectoring PVY. A problem would only exist if the there was some virus already present in the field you were trying to protect.

We continue to hear reports or grower dissatisfaction with the aphid control obtained using Fulfill (pymetrozine). Performance seems most problematic when low volume applications are made, especially with those applied by air. There is some suspicion that potato aphid may be more difficult to control that green peach aphid. In our insecticide efficacy trials at Rosemount, we have had good success with this product against both ot these aphids. We have tested the product under extreme green peach aphid pressure giving us considerable confidence in that data; typically we get >98% control. In our experiments, potato aphid pressure has been too low to severely test the product, but we are getting >90% control. Fulfill kills aphids very slowly (5-7 days may be required before the insect dies), but feeding activity ceases almost immediately. However, it may be that if application does not penetrate the canopy that UL light may reduce the effective life of the product.

Captures of winged aphids (mean number per trap), 1992-1994 & 1998-2000. Data for Minnesota and North Dakota locations in the Aphid Alert trapping network.

graph showing captures of winged green peach aphids per trap from 1992-1994 and 1998-2000

Fig. 1. Captures of winged green peach aphid per trap.

graph showing captures of potential PVY vectors other than green peach aphids per trap from 1992-1994 and 1998-2000

Fig. 2. Captures potential PVY vectors other than green peach aphid per trap.

graph showing captures of winged turnip aphids per trap from 1992-1994 and 1998-2000

Fig. 3. Captures of winged turnip aphid per trap.

graph showing captures of winged small grain aphids per trap from 1992-1994 and 1998-2000

Fig. 4. Captures of winged small grain aphids (i.e., bird cherry-oat aphid, English grain aphid and greenbug) per trap.

graph showing captures of sunflower aphids per trap from 1992-1994 and 1998-2000

Fig. 5. Captures of sunflower aphid per trap.

graph showing captures of other potential PVY vectors per trap from 1992-1994 and 1998-2000

Fig. 6. Captures of other potential PVY vectors (including potato aphid, corn leaf aphid, thistle aphid, and others) per trap.

 

 

Aphid captures per trap by location for week ending 13 August

Minnesota

Minnesota Baker
14 August
Barnesville
14 August
Climax
15 August
Crookston
14 August
Gully
14 August
Hollandale
No data
  Aphids per trap per week
Species PLRV/PVY vectors  
green peach aphid 2 (2.7) 4 (0.8) 4 (2.2)   1 (0.9)  
potato aphid            
  PVY vectors
bird cherry-oat aphid 2 (2.7) 2 (0.4) 1 (0.5)   2 (1.8)  
corn leaf aphid 22 (29.3) 2 (0.4)     47 (42.7)  
English grain aphid   1 (0.2)     2 (1.8)  
greenbug            
sunflower aphid   1 (0.2) 1 (0.5)   10 (9.1)  
thistle aphid 4 (5.3) 1 (0.2) 8 (4.4)   3 (2.7)  
turnip aphid 18 (24) 459 (33.7) 142 (77.2)   9 (8.2)  
Other PVY vectors 2 (2.7) 3 (0.3) 3 (2.7)      
  Non-vectors and unidentified
non-vectors 18 (24) 10 (2) 4 (2.2)   17 (15.5)  
unidentified 5 (6.7) 7 (1.4) 10 (5.4)   16 (14.6)  
Totals 75 490 184   110  

Minnesota

Minnesota Karlstad
14 August
Little Falls
No data
Rice
14 August
Rosemount
14 August
Thief River
No data
Williams
14 August
  Aphids per trap per week
Aphid species PLRV/PVY vectors
green peach aphid 1 (9.1)     3 (2.2)    
potato aphid 1 (9.1)          
  PVY vectors
bird cherry-oat aphid 1 (9.1)     5 (3.7)    
corn leaf aphid 4 (36.4)     100 (74.1)   82 (67.8)
English grain aphid 1 (9.1)         3 (2.5)
greenbug            
sunflower aphid            
thistle aphid 1 (9.1)     1 (0.7)   2 (1.7)
turnip aphid 1 (9.1)     3 (2.2)   13 (10.7)
Other PVY vectors       9 (6.7)   3 (2.5)
  Non-vectors and unidentified
non-vectors 1 (9.1)     2 (1.5)   13 (10.7)
unidentified            
Totals 11     135   121

North Dakota

North Dakota Cando
11 August
Hoople
11 August
Linton
14 August
Mandan
14 August
Minot
9 August
Rolette
11 August
Walhalla
11 August
  Aphids per trap per week
Aphid species PLRV/PVY vectors
green peach aphid 7 (12.3)   1 (0.7) 2 (1.3) 9 (7.6) 7 (11.3) 9 (2.6)
potato aphid     1 (0.7) 1 (0.7) 4 (3.4)   2 (0.6)
PVY vectors
bird cherry-oat aphid 4 (7) 1 (3.3) 3 (2.2) 9 (6.0) 3 (2.5) 27 (43.6) 10 (2.9)
corn leaf aphid 23 (40.4) 20 (66.7) 77 (56.6) 99 (66.0) 34 (28.8)   207 (60.2)
English grain aphid 3 (5.3)   1 (0.7) 1 (0.7) 8 (6.8) 2 (3.2) 11 (3.2)
greenbug     1 (3.3)        
sunflower aphid   1 (3.3)         1 (0.3)
thistle aphid 5 (8.8)   5 (3.7) 5 (3.3) 10 (8.5) 3 (4.8) 9 (2.6)
turnip aphid 10 (17.5) 8 (26.7) 31 (22.8) 15 (10) 26 (22) 13 (21) 48 (14)
other PVY vectors     4 (2.9) 1 (0.7) 9 (7.6)   30 (8.7)
Non-vectors and unidentified
non-vectors 4 (7)   4 (2.9) 2 (1.3) 7 (5.9) 5 (8.1) 8 (2.3)
unidentified 1 (1.8)   7 (5.2) 15 (10) 8 (6.8) 5 (8.1) 9 (2.6)
Totals 57 30 136 150 118 62 344

Wisconsin

Wisconsin Antigo
14 August
Rhinelander
14 August
  Aphids per trap per week
Aphid species PLRV/PVY vectors
green peach aphid 1 (3.9)  
potato aphid    
  PVY vectors
bird cherry-oat aphid    
corn leaf aphid 24 (93.2) 69 (98.6)
English grain aphid    
greenbug    
sunflower aphid    
thistle aphid   1 (1.4)
turnip aphid 1 (3.9)  
other PVY vectors    
  Non-vectors and unidentified
non-vectors    
unidentified    
Totals 26 70

South Dakota

South Dakota Watertown
14 August
  Aphids per trap per week
Aphid species PLRV/PVY vectors
green peach aphid  
potato aphid  
  PVY vectors
bird cherry-oat aphid  
corn leaf aphid 3 (100)
English grain aphid  
greenbug  
sunflower aphid  
thistle aphid  
turnip aphid  
other PVY vectors  
  Non-vectors and unidentified
non-vectors  
unidentified  
Totals 3

Nebraska

Nebraska Cody
14 August
  Aphids per trap per week
Aphid species PLRV/PVY vectors
green peach aphid  
potato aphid  
  PVY vectors
bird cherry-oat aphid 2 (14.3)
corn leaf aphid 10 (71.4)
English grain aphid  
greenbug  
sunflower aphid  
thistle aphid 1 (7.1)
turnip aphid  
other PVY vectors 1 (7.1)
  Non-vectors and unidentified
non-vectors  
unidentified  
Totals 14