This week we are starting to see some major aphid captures. Soybean aphid numbers of ballooned with six sites collected them in the double digits. Starting to see more English grain aphid in some areas as well. More importantly, we caputred 12 green peach aphids this week from four locations including seven from Ada. Ada had a whopping 107 vectors with a PVY Risk Index of 21.4. Other locations with high PVY Risk Indices include Perham (7.91), Sabin (6.27), Motley (5.82), and Crookston (5.41). The Langdon, Sabin, and Tappen traps all had PVY Risk Indices below 1.0.
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.