Green peach aphid (one of the most important and most effective vectors of PVY) was detected in both the Linton ND and Gully MN sites. A number of other vector species were recovered from a number of sites - the presence of any PVY vector is cause to scout and manage accordingly. Overall, aphid numbers were lower than last week; this may be a reflection of changing weather patterns or a decrease in movement from alternate host species.
A number of non-vector aphid species were recovered. While these aphids do not cause a concern for the transmission of PVY, they are indicative of aphid movement in an area. We still have not recovered soybean aphid in suction traps this summer but reports from southern MN indicate several fields there have populations that have crossed treatment thresholds. Early August is the prime period for summer movement of soybean aphid.
To scout for aphids in potatoes, select leaves from the lower to mid canopy. Lower, older leaves will have more established colonies and aphids prefer the balance of nutrients found here; aphids are rarely found on leaves in the upper canopy. Avoid leaves on the ground or in contact with the soil. In seed potatoes there is only a threshold for PLRV (10 aphids/100 leaves), reactive application of insecticides an effective control for PVY. However, the use of feeding suppressing insecticides, such as Fulfill (Syngenta Crop Protection) or Beleaf (FMC Corp.) and refined crop oils, such as Aphoil and JMS Stylet Oil, at or prior to field colonization by aphids may reduce the transmission of PVY within fields. In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.
Aphid Species Captured (per
suction trap 7/25/2012 – 8/01/2012)
|
|||||||||
Cando
ND
|
Forest
River ND
|
Linton
ND
|
Lake
of the Woods MN
|
Gully
MN
|
Stephen
MN
|
Sabin
MN
|
Perham
MN
|
Staples
MN
|
|
Green peach aphid (Myzus persicae)
|
1
|
1
|
|||||||
Soybean aphid
(Aphid glycines)
|
|||||||||
OTHER PVY VECTORS
|
|||||||||
Bird cherry oat aphid (Rhopalosiphum padi)
|
1
|
||||||||
Corn leaf aphid (Rhopalosiphum maidis)
|
3
|
3
|
2
|
||||||
English grain aphid (Sitobion avenae)
|
1
|
1
|
1
|
3
|
1
|
||||
Green bug (Schizaphis graminum)
|
|||||||||
Potato aphid (Macrosiphum euphorbiae)
|
|||||||||
Sunflower aphid (Aphis helianthi)
|
|||||||||
Thistle aphid (Lipaphis erysimi) |
1
|
||||||||
Turnip aphid (Brevicoryne brassicae)
|
|||||||||
Cotton/melon aphid (Aphis gossypii)
|
2
|
2
|
2
|
||||||
Pea aphid (Acyrthosiphon pisum)
|
|||||||||
Cowpea aphid (Aphis craccivora)
|
|||||||||
black bean aphid (Aphis fabae)
|
|||||||||
Buckthorn aphid (Aphis nasturii)
|
1
|
2
|
|||||||
Identified NON-VECTOR species
|
1
|
1
|
8
|
11
|
5
|
2
|
8
|
||
Unidentified
|
|||||||||
Total # captured
|
2
|
5
|
1
|
12
|
17
|
8
|
7
|
12
|
|
