Friday, August 22, 2014

Trap Catches Identified to Aug 22.
Here are the trap catches we received up to Aug 22.

Aphid vector numbers were up for A THIRD WEEK IN A ROW! Probably because the temperatures last week were excellent for aphid reproduction and numbers were increasing.  This may well have led to an increase in winged aphids, resulting in higher trap catches.

Trap catches increased at a number of locations over last week and decreased in some others.  Numbers were up in Ada, Erskine, Hallock, Hoople, Langdon, Linton I, Perham, Staples, Stephen and Walhalla and down at other sites. Approximately 80 more aphids were recovered overall from all traps compared to last week.

Green peach aphids were recovered from Ada (2), Erskine (1), Forest River (3), Hatton (1), Langdon (3), Staples (1), Stephen (4), and Walhalla (1).  Soybean aphids were recovered from Ada (29), Crookston (5), Erskine (4), Forest River (15), Hallock (2), Hatton (10), Hoople (3), Perham (27), Sabin (1), Staples (4), and Stephen (6). It looks like several locations received flights of soybean aphids.  Other species captured at multiple locations in higher numbers included Bird cherry oat aphid, corn leaf aphid, greenbug and pea aphid.

Most of our PVY transmission in MN and ND occurs late in the season.  Increasing aphid vector numbers is a prime driver in this.  If you're in a position to do so, killing vines prior to or early in the arrival of the heaviest vector flights may be a management tactic to consider.

Keep Scouting!
Scouting 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.
 - The use of feeding suppressing insecticides, such as pymetrozine (Fulfill®) or flonicamid (Beleaf®) 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. Some other insecticides, such as clothianidin (Belay®), imidacloprid (Admire Pro® or Provado®), and spirotetramat (Movento®), have also been demonstrated to reduce the transmission of PVY.
- In table stock potatoes, a treatment threshold of 30 aphids /100 leaves should deter yield loss due to aphid feeding.