Tuesday, August 21, 2012


Here's the catch for the Trapping Period ending Aug 15

Green peach aphid (one of the most important and most effective vectors of PVY) was detected in 4 trap locations;  the Forest River ND, Lake of the Woods MN, Sabin MN and Staples MN sites. If seed potato vines have not yet been killed at these sites, it should be noted that green peach is the most efficient vector of PVY.   For the second week soybean aphids were recovered at 1 location but their presence and flight remains low. Southern MN is reporting increased soybean aphid populations but it is not clear of these populations will disperse to northern areas. 

There were significant flights of both bird cherry oat and buckthorn aphids in several locations.  While neither is the most efficient vector of virus disease, the presence of any PVY vector is cause to scout and manage accordingly.  At most sites there was a slight decrease in the numbers of vectors recovered from traps with the exception of Lake of the Woods, which saw a significant increase.  It should be noted, however, that Lake of the Woods trap contents from 8/08 and 8/15 had to be combined, and so this increase reflects 2 weeks of sample effort. 

The number of non-vector aphid species recovered in most traps was down this week, indicating overall aphid movement may have been suppressed by colder temperatures.

As always - 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 8/08/2012 – 8/15/2012)

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

2


1

1
Soybean aphid
(Aphid glycines)






2


 OTHER PVY VECTORS
Bird cherry oat aphid (Rhopalosiphum padi)



32
2
1
9
3

Corn leaf aphid (Rhopalosiphum maidis)



1

4
1

1
English grain aphid (Sitobion avenae)
 4




1



Green bug (Schizaphis graminum)









Potato aphid (Macrosiphum euphorbiae)




2

1
1

Sunflower aphid (Aphis helianthi)









Thistle aphid (Lipaphis erysimi)






1

1
Turnip aphid (Brevicoryne brassicae)









Cotton/melon aphid (Aphis gossypii)









Pea aphid (Acyrthosiphon pisum)









Cowpea aphid (Aphis craccivora)


1

2


1
1
black bean aphid (Aphis fabae)









Buckthorn aphid (Aphis nasturii)



24
1


2
2
Identified non-vectored species

1
1
1

6
23
1
1
Unidentified



2





Total # captured
4
2
2
62
7
12
38
8
7
Total Verctors
4
1
1
61
7
6
15
7
6