Friday, September 6, 2013

Here's the catch for Samples Identified up to Sept 6*
Aphid trap captures were lower in all locations but one.

We are getting later in the season but aphids are still flying; numbers are definitely down this week but both soybean and green peach aphids are making appearances in more locations.  Aphid suction trap captures were lower than last week in all locations save Lake of the Woods (which had its largest capture to date, 40 vector species).  Several locations, while down from last week, still had high numbers of aphid vectors; Hoople, Hatton and Forest River, ND captured 24, 19 and 32 vectors species (respectively) while the trap at the Staples location captured 16 aphids.

Some of the more important vector species were captured in higher numbers than they have been in previous weeks. Green peach aphids were recovered from Cando, Hoople and Crookston this week, while soybean aphids showed up in the traps at Cando, Hoople, Forest River, Hatton, Sabin, Perham and Staples.  These may represent movement of soybean aphids back to Buckthorn (their overwintering host), Buckthorn aphids (closely related to soybean aphid) were also flying this week and were recovered in traps from Forest River, Hatton, Gully and Crookston.  A relatively large flight of potato aphids was recovered from the trap at Hatton and cereal aphids were still present in numbers at several locations, over half of the aphids trapped this week in the Lake of the Woods trap were bird cherry oat aphids (24 of 40 captured).  These may have been coming off turf grass and grass seed fields.

We continue to have an aphid year, so if you still have plants in the field that have not yet started to die back or have not yet been killed...

Scouting & treating 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 standard broad-spectrum insecticides are not an effective control for PVY (by the time the aphid has been exposed and dies, it can have moved PVY inoculum into and, more importantly, within the field.
  • 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
Always read the label!!

* These trap catches sorted and ID'd in this report were trapped in the previous week.  It generally takes 2 days to receive trap catches after being returned by a cooperator and then 1-2 days to be sorted and ID'd.  The results will be updated again Aug 23.  If needed, contact the lab at  218.281.8633 and ask for Ian or Nate...

Weekly Trap Catch (click on the image for larger version)   

Cumulative Seasonal Catch (click on the image for larger version)